Kubota DG-972 Factory Manual. - ALL Power Labs

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Transcript

WORKSHOP MANUAL
GASOLINE,LPG,
NATURAL GAS ENGINE
WG972-E2,DF972-E2,
DG972-E2
KiSC issued 06, 2009 A
TO THE READER
This Workshop Manual tells the servicing personnel about the mechanism, servicing and
maintenance of the WG972-E2, DF972-E2 and DG972-E2. It contains 4 parts: "Information",
"General", "Mechanism" and "Servicing".
Information
This section contains information below.
• Safety First
• Specification
• Performance Curve
• Important Items of Exhaust Emission Regulation
• Dimension
• Wiring Diagram
General
This section contains information below.
• Engine Identification
• General Precautions
• Maintenance Check List
• Check and Maintenance
• Special Tools
Mechanism
This section contains information on the structure and the function of the unit. Before you continue
with the subsequent sections, make sure that you read this section.
Refer to the latest version of Workshop Manual (Code No. 9Y021-01870 / 9Y021-18200) for the
diesel engine / tractor mechanism that this workshop manual does not include.
Servicing
This section contains information below.
• Troubleshooting
• Servicing Specifications
• Tightening Torques
• Checking, Disassembling and Servicing
All illustrations, photographs and specifications contained in this manual are of the newest
information available at the time of publication.
KUBOTA reserves the right to change all information at any time without notice.
Since this manual includes many models, information or illustrations and photographs can show
more than one model.
February, 2009
© KUBOTA Corporation 2009
KiSC issued 06, 2009 A
I INFORMATION
KiSC issued 06, 2009 A
CONTENTS
1. SAFETY FIRST .............................................................................................................................. I-1
2. SPECIFICATIONS.......................................................................................................................... I-4
3. IMPORTANT ITEMS OF EXHAUST EMISSION REGULATION.................................................... I-6
[1] INLET AND EXHAUST SYSTEM ............................................................................................. I-6
[2] ALTITUDE COMPENSATION KIT (WG972-E2, DF972-E2) .................................................... I-6
[3] LPG REGULATOR WITH VAPORIZER (DF972-E2) ............................................................... I-6
[4] KUBOTA RECOMMENDED LPG FUEL SPECIFICATIONS (DF972-E2)................................ I-6
[5] LENGTH OF THE LPG VAPOR HOSE (DF972-E2) ................................................................ I-6
[6] GAS REGULATOR (DG972-E2) .............................................................................................. I-7
[7] KUBOTA RECOMMENDED FUEL SPECIFICATIONS (DG972-E2) ....................................... I-7
[8] LENGTH OF THE GAS HOSE (DG972-E2)............................................................................. I-7
4. PERFORMANCE CURVES............................................................................................................ I-8
5. DIMENSIONS............................................................................................................................... I-10
6. WIRING DIAGRAM....................................................................................................................... I-14
INFORMATION
KiSC issued 06, 2009 A
INFORMATIONWG972-E2,DF972-E2,DG972-E2, WSM
I-1
1. SAFETY FIRST
WSM000001INI0001US0
BEFORE YOU START SERVICE
• Read all instructions and safety instructions in this
manual and on your engine safety decals.
• Clean the work area and engine.
• Park the machine on a stable and level ground.
• Let the temperature of the engine decrease before
you start a job.
• Stop the engine, then remove the key.
• Disconnect the battery negative cable.
• Hang a "DO NOT OPERATE" tag in the operator
station.
WSM000001INI0002US0
START SAFELY
• Do not do the procedures below when you start the
engine.
– short across starter terminals
– bypass the safety start switch
• Do not make unauthorized modifications to the
engine. This can cause damage and decrease the
engine life.
WSM000001INI0003US0
SAFETY FIRST
• This symbol, the industry's "Safety Alert Symbol", is used throughout this manual and on labels on the
machine itself to warn of the possibility of personal injury. Read these instructions carefully.
• It is essential that you read the instructions and safety regulations before you attempt to repair or use
this unit.
DANGER
• Indicates an imminently hazardous situation which, if not avoided, will result in death or serious injury.
WARNING
• Indicates a potentially hazardous situation which, if not avoided, could result in death or serious injury.
CAUTION
• Indicates a potentially hazardous situation which, if not avoided, may result in minor or moderate
injury.
IMPORTANT
• Indicates that equipment or property damage could result if instructions are not followed.
NOTE
• Gives helpful information.
KiSC issued 06, 2009 A
INFORMATIONWG972-E2,DF972-E2,DG972-E2, WSM
I-2
OPERATE SAFELY
• Do not use the machine after you consume alcohol
or medication or when you are tired.
• Put on applicable clothing and safety equipment.
• Use applicable tools only. Do not use alternative
tools or parts.
• When 2 or more persons do servicing, make sure
that you do it safely.
• Do not touch the hot parts or parts that turn when the
engine operates.
• Do not remove the radiator cap when the engine
operates, or immediately after it stops. If not, hot
water can spout out from the radiator. Only remove
the radiator cap when it is at a sufficiently low
temperature to touch with bare hands. Slowly loosen
the cap to release the pressure before you remove it
fully.
• Released fluid (fuel or hydraulic oil) under pressure
can cause damage to the skin and cause serious
injury. Release the pressure before you disconnect
hydraulic or fuel lines. Tighten all connections before
you apply the pressure.
• Do not open a fuel system under high pressure.
The fluid under high pressure that stays in fuel lines
can cause serious injury. Do not disconnect or repair
the fuel lines, sensors, or any other components
between the fuel pump and injectors on engines with
a common rail fuel system under high pressure.
• Put on an applicable ear protective device (earmuffs
or earplugs) to prevent injury against loud noises.
• Be careful about electric shock. The engine
generates a high voltage of more than DC100 V in
the ECU and is applied to the injector.
WSM000001INI0004US0
PREVENT A FIRE
• Fuel is very flammable and explosive under some
conditions. Do not smoke or let flames or sparks in
your work area.
• To prevent sparks from an accidental short circuit,
always disconnect the battery negative cable first
and connect it last.
• The battery gas can cause an explosion. Keep the
sparks and open flame away from the top of battery,
especially when you charge the battery.
• Make sure that you do not spill fuel on the engine.
WSM000001INI0005US0
KiSC issued 06, 2009 A
INFORMATIONWG972-E2,DF972-E2,DG972-E2, WSM
I-3
KEEP A GOOD AIRFLOW IN THE WORK AREA
• If the engine is in operation, make sure that the area
has good airflow. Do not operate the engine in a
closed area. The exhaust gas contains poisonous
carbon monoxide.
WSM000001INI0006US0
DISCARD FLUIDS CORRECTLY
• Do not discard fluids on the ground, down the drain,
into a stream, pond, or lake. Obey related
environmental protection regulations when you
discard oil, fuel, coolant, electrolyte and other
dangerous waste.
WSM000001INI0007US0
PREVENT ACID BURNS
• Keep electrolyte away from your eyes, hands and
clothing. Sulfuric acid in battery electrolyte is
poisonous and it can burn your skin and clothing and
cause blindness. If you spill electrolyte on yourself,
clean yourself with water, and get medical aid
immediately.
WSM000001INI0008US0
PREPARE FOR EMERGENCIES
• Keep a first aid kit and fire extinguisher ready at all
times.
• Keep the emergency contact telephone numbers
near your telephone at all times.
WSM000001INI0009US0
KiSC issued 06, 2009 A
INFORMATIONWG972-E2,DF972-E2,DG972-E2, WSM
I-4
2. SPECIFICATIONS
*The specification described above is of the standard engine of each model.
*Conversion Formula : HP = 0.746 kW, PS = 0.7355 kW
Model WG972-E2 DF972-E2
Number of Cylinder 3
Type Vertical, water cooled, 4-cycle Gasoline engine
Vertical, water cooled, 4-cycle Dual Fuel (Gasoline / LPG)
engine
Gasoline fuel LPG fuel
Bore × Stroke 74.5 x 73.6 mm (2.93 x 2.90 in.)
Total Displacement 962 cm3 (58.7 cu.in.)
ISO Net Continuous 18.6 kW / 3600 min
-1 (rpm)
25.0 HP / 3600 min-1 (rpm)
17.5 kW / 3600 min-1 (rpm)
23.5 HP / 3600 min-1 (rpm)
ISO / SAE Net Intermittent 23.1 kW / 3600 min
-1 (rpm)
31.0 HP / 3600 min-1 (rpm)
22.0 kW / 3600 min-1 (rpm)
29.5 HP / 3600 min-1 (rpm)
SAE Gross Intermittent 24.2 kW / 3600 min
-1 (rpm)
32.5 HP / 3600 min-1 (rpm)
23.1 kW / 3600 min-1 (rpm)
31.0 HP / 3600 min-1 (rpm)
Maximum Bare Speed 3850 to 3950 min-1 (rpm)
Minimum Bare Idling Speed 1400 to 1600 min-1 (rpm)
Cylinder Head Overhead-Valve
Ignition System Distributor-Less Solid Stage Type
Governor Centrifugal Ball Mechanical Type / Electronic Governor
Direction of Rotation Counter-Clockwise (Viewed from flywheel)
Spark Plug NGK BKR4E
Ignition Timing 0.37 rad (21 °) before T.D.C. / 3600 min-1 (rpm)
Firing Order 1-2-3
Compression Ratio 9.2 : 1
Lubricating System Forced Lubrication by Trochoid Pump
Oil Pressure Indication Electrical Type Switch
Lubricating Filter Full Flow Paper Filter (Cartridge Type)
Cooling System Pressurized Radiator (not included in the basic model), Forced Circulation with Water Pump
Starting System Electric Starting with Starter
Starting Motor 12V, 1.0 kW
Battery 12 V, 52 AH or equivalent
Charging Alternator 12 V, 150 W
Fuel *Unleaded Automobile Gasoline Standard Commercial LP Gas
Lubricating Oil Better than SH Class (API)
Lubricating Oil Capacity 3.4 L (0.90 U.S.gals)
Weight (Dry) 72.0 kg (159 lbf)
Application General Power Source
KiSC issued 06, 2009 A
INFORMATIONWG972-E2,DF972-E2,DG972-E2, WSM
I-5
*The specification described above is of the standard engine of each model.
*Conversion Formula : HP = 0.746 kW, PS = 0.7355 kW
9Y1210318INI0001US0
Model DG972-E2-BBH DG972-E2-SAEH
Number of Cylinder 3
Type Vertical, water cooled, 4-cycle Natural Gas engine
Bore × Stroke 74.5 x 73.6 mm (2.93 x 2.90 in.)
Total Displacement 962 cm3 (58.7 cu.in.)
ISO Net Continuous 14.5 kW / 3600 min
-1 (rpm)
19.4 HP / 3600 min-1 (rpm)
ISO / SAE Net Intermittent 17.6 kW / 3600 min
-1 (rpm)
23.6 HP / 3600 min-1 (rpm)
SAE Gross Intermittent 18.7 kW / 3600 min
-1 (rpm)
25.1 HP / 3600 min-1 (rpm)
Maximum Bare Speed 3850 to 3950 min-1 (rpm)
Minimum Bare Idling Speed 1400 to 1600 min-1 (rpm)
Cylinder Head Overhead-Valve
Ignition System Distributor-Less Solid Stage Type
Governor Centrifugal Ball Mechanical Type / Electronic Governor
Direction of Rotation Counter-Clockwise (Viewed from flywheel)
Spark Plug NGK BKR4E
Ignition Timing 0.49 rad (28 °) before T.D.C. / 3600 min-1 (rpm)
Firing Order 1-2-3
Compression Ratio 9.2 : 1
Lubricating System Forced Lubrication by Trochoid Pump
Oil Pressure Indication Electrical Type Switch
Lubricating Filter Full Flow Paper Filter (Cartridge Type)
Cooling System Pressurized Radiator (not included in the basic model), Forced Circulation with Water Pump
Starting System Electric Starting with Starter
Starting Motor 12V, 1.0 kW
Battery 12 V, 52 AH or equivalent
Charging Alternator 12 V, 480 W
Fuel Natural Gas
Lubricating Oil Better than SH Class (API)
Lubricating Oil Capacity 3.4 L (0.90 U.S.gals)
Weight (Dry) 72.0 kg (159 lbf) 95.4 kg (210 lbf)
Application General Power Source
KiSC issued 06, 2009 A
INFORMATIONWG972-E2,DF972-E2,DG972-E2, WSM
I-6
3. IMPORTANT ITEMS OF EXHAUST EMISSION
REGULATION
To conform with U.S. EPA and CARB SOREs (Small Off Road Engines) emission regulations, the WG972-E2,
DF972-E2 and DG972-E2 engine must observe below items.
9Y1210318INI0002US0
[1] INLET AND EXHAUST SYSTEM
The WG972-E2, DF972-E2 and DG972-E2 engine must use the below air cleaner and inlet pipe, and exhaust
back pressure of the muffler must be within the below values.
Any modifications to the fuel system or any adjustments made on this engine will cause this engine to be in
non-compliance with emission regulations.
9Y1210318INI0003US0
[2] ALTITUDE COMPENSATION KIT (WG972-E2, DF972-E2)
IMPORTANT
• Altitude compensation kit is applied for EPA and CARB certified engines only.
EPA and CARB emission regulations require the ultimate user of non-road SI engine, as their obligation,
to adjust the emissions by installing the appropriate genuine altitude compensation kit. And the engine
manufacturer must provide such kit when engine is operated at an altitude that exceeds the standard
level, as guarantied by the engine manufacturer. For this purpose, KUBOTA prepared genuine altitude
compensation kit described below. The ultimate users of SI engine must comply with the regulations
through the installation of the appropriate altitude compensation kit for the altitude range where the
engine will be operated.
• "Replacement of Altitude Compensation Kit" for reference to the exchange of altitude compensation kit.
9Y1210318INI0004US0
[3] LPG REGULATOR WITH VAPORIZER (DF972-E2)
When operating DF972-E2 on LPG, only a KUBOTA GENUINE LPG REGULATOR KIT can be used.
9Y1210318INI0005US0
[4] KUBOTA RECOMMENDED LPG FUEL SPECIFICATIONS
(DF972-E2)
• Commercial Propane gas only.
• Equivalent to Propane H-D-5 of GPA* standards.
*GPA means Gas Processors Association (U.S.A.)
9Y1210318INI0006US0
[5] LENGTH OF THE LPG VAPOR HOSE (DF972-E2)
The length of the LPG vapor hose between the LPG carburetor and LPG vaporizer must be within 280 to 320 mm
(11.1 to 12.5 in.)
The incorrect use of the hose may not conform to EPA and CARB EMISSION REGULATIONS.
9Y1210318INI0007US0
Part Part No.
Genuine air cleaner 1G657-1101-1
Genuine inlet pipe EG561-1164-1
Brake horse power SAE net int. Allowable maximum exhaust back pressure
23.1 kP (31.0 HP) / 3600 min-1 (rpm) 19.6 kPa (147 mmHg) / 3600 min-1 (rpm)
Altitude Compensation Kit Applicable Altitude Ranges
Original Carburetor (with 0 m (0 ft) kit) 0 to 700 m (0 to 2300 ft)
1000 m (3281 ft) compensation kit 300 to 1700 m (984 to 5577 ft)
2000 m (6562 ft) compensation kit 1300 to 2700 m (4265 to 8858 ft)
C3H8 C3H6 C4H10 Others
≥ 90 % ≤ 5 % ≤ 2.5 % −
KiSC issued 06, 2009 A
INFORMATIONWG972-E2,DF972-E2,DG972-E2, WSM
I-7
[6] GAS REGULATOR (DG972-E2)
When operating DG972-E2 on natural gas, only a KUBOTA GENUINE GAS REGURATOR can be used.
9Y1210318INI0008US0
[7] KUBOTA RECOMMENDED FUEL SPECIFICATIONS (DG972-E2)
• Natural gas only.
• Consult KUBOTA for further information of fuel used.
9Y1210318INI0009US0
[8] LENGTH OF THE GAS HOSE (DG972-E2)
The length of the gas hose between the gas mixer and gas regulator must be within 280 to 320 mm (11.1 to
12.5 in.).
The incorrect use of the hose may not conform to EPA and CARB EMISSION REGULATIONS.
9Y1210318INI0010US0
KiSC issued 06, 2009 A
INFORMATIONWG972-E2,DF972-E2,DG972-E2, WSM
I-8
4. PERFORMANCE CURVES
WG972
DF972
(1) Brake Horsepower
(2) Engine Speed
(3) Specific Fuel Consumption
(4) Torque
(5) Net Intermittent Torque
(6) Net Continuous Torque
(7) Net Intermittent Brake
Horsepower
(8) Net Continuous Brake
Horsepower
(9) Net Intermittent Specific Fuel
Consumption
a : Gasoline Use
b : LP Gas Use
KiSC issued 06, 2009 A
INFORMATIONWG972-E2,DF972-E2,DG972-E2, WSM
I-9
DG972
9Y1210318INI0011US0
(1) Brake Horsepower
(2) Engine Speed
(3) Specific Fuel Consumption
(4) Torque
(5) Net Intermittent Torque
(6) Net Continuous Torque
(7) Net Intermittent Brake
Horsepower
(8) Net Continuous Brake
Horsepower
(9) Net Intermittent Specific Fuel
Consumption
KiSC issued 06, 2009 A
INFORMATIONWG972-E2,DF972-E2,DG972-E2, WSM
I-10
5. DIMENSIONS
WG972, DF972
9Y1210318INI0012US0
KiSC issued 06, 2009 A
INFORMATIONWG972-E2,DF972-E2,DG972-E2, WSM
I-11
WG972, DF972 (Electronic Governor Model)
9Y1210318INI0013US0
KiSC issued 06, 2009 A
INFORMATIONWG972-E2,DF972-E2,DG972-E2, WSM
I-12
DG972-E2-BBH
9Y1210318INI0014US0
KiSC issued 06, 2009 A
INFORMATIONWG972-E2,DF972-E2,DG972-E2, WSM
I-13
DG972-E2-SAEH
9Y1210318INI0015US0
KiSC issued 06, 2009 A
INFORMATIONWG972-E2,DF972-E2,DG972-E2, WSM
I-14
6. WIRING DIAGRAM
9Y1210318INI0016US0
KiSC issued 06, 2009 A
G GENERAL
KiSC issued 06, 2009 A
CONTENTS
1. ENGINE IDENTIFICATION .......................................................................................................... G-1
[1] MODEL NAME AND ENGINE SERIAL NUMBER.................................................................. G-1
[2] CYLINDER NUMBER............................................................................................................. G-4
2. GENERAL PRECAUTIONS.......................................................................................................... G-5
3. MAINTENANCE CHECK LIST ..................................................................................................... G-6
4. CHECK AND MAINTENANCE ..................................................................................................... G-8
[1] DAILY CHECK POINTS ......................................................................................................... G-8
[2] CHECK POINTS OF INTIAL 50 HOURS ............................................................................. G-10
[3] CHECK POINTS OF EVERY 50 HOURS ............................................................................ G-11
[4] CHECK POINTS OF EVERY 100 HOURS .......................................................................... G-13
[5] CHECK POINTS OF EVERY 200 HOURS .......................................................................... G-14
[6] CHECK POINTS OF EVERY 1 YEAR.................................................................................. G-15
[7] CHECK POINTS OF EVERY 1000 HOURS ........................................................................ G-18
[8] CHECK POINTS OF EVERY 2 YEARS ............................................................................... G-21
5. SPECIAL TOOLS ....................................................................................................................... G-26
GENERAL
KiSC issued 06, 2009 A
GENERALWG972-E2,DF972-E2,DG972-E2, WSM
G-1
1. ENGINE IDENTIFICATION
[1] MODEL NAME AND ENGINE SERIAL NUMBER
When contacting the manufacture, always specify your engine
model name and serial number.
The engine model and its serial number need to be identified
before the engine can be serviced or parts replaced.
Engine Serial Number
The engine serial number is an identified number for the engine.
It is marked after the engine model number.
It indicates month and year of manufacture as follows.
Year of manufacture
(To be continued)
Alphabet or
Number Year
Alphabet or
Number Year
1 2001 F 2015
2 2002 G 2016
3 2003 H 2017
4 2004 J 2018
5 2005 K 2019
6 2006 L 2020
7 2007 M 2021
8 2008 N 2022
9 2009 P 2023
A 2010 R 2024
B 2011 S 2025
C 2012 T 2026
D 2013 V 2027
E 2014
(1) Engine Model Name and Serial
Number
[A] WG972-E2
[B] DF972-E2
[C] DG972-E2
KiSC issued 06, 2009 A
GENERALWG972-E2,DF972-E2,DG972-E2, WSM
G-2
(Continued)
Month of manufacture
* Alphabetical letters "I" and "O" are not used.
e.g.
• WG972
(a)
- 8
(b)
B
(c)
A001
(d)
• DF972
(a)
- 8
(b)
B
(c)
A001
(d)
• DG972
(a)
- 8
(b)
B
(c)
A001
(d)
9Y1210318GEG0003US0
Emission Label
This label is attached on the cylinder head cover of the engine
certified to the requirements of EPA / CARB Emission regulations.
The content of the label is approved officially by EPA / CARB.
9Y1210318GEG0004US0
Month Engine Lot Number
January A0001 ~ A9999 B0001 ~ BZ999
February C0001 ~ C9999 D0001 ~ DZ999
March E0001 ~ E9999 F0001 ~ FZ999
April G0001 ~ G9999 H0001 ~ HZ999
May J0001 ~ J9999 K0001 ~ KZ999
June L0001 ~ L9999 M0001 ~ MZ999
July N0001 ~ N9999 P0001 ~ PZ999
August Q0001 ~ Q9999 R0001 ~ RZ999
September S0001 ~ S9999 T0001 ~ TZ999
October U0001 ~ U9999 V0001 ~ VZ999
November W0001 ~ W9999 X0001 ~ XZ999
December Y0001 ~ Y9999 Z0001 ~ ZZ999
(a) Engine Model Name : WG972, DF972, DG972
(b) Year : 8 indicates 2008
(c) Month : A or B indicates January
(d) Lot Number : (0001 ~ 9999 or A001 ~ Z999)
KiSC issued 06, 2009 A
GENERALWG972-E2,DF972-E2,DG972-E2, WSM
G-3
Tamper Resistance
KUBOTA Corporation is to provide safeguards for the parts
where never to be adjusted, and is approved by EPA / CARB for the
purpose of this engine to be in compliance with EPA / CARB
Emission Regulations through its useful life. Intentional removal and
adjustment of such tamper resistance are subject to the penalty.
9Y1210318GEG0005US0
(1) Tamper Resistance [A] Carburetor
[B] Pick-up Sensor
[C] Vaporizer
[D] Regulator
[E] Governor Lever
KiSC issued 06, 2009 A
GENERALWG972-E2,DF972-E2,DG972-E2, WSM
G-4
[2] CYLINDER NUMBER
The cylinder numbers of KUBOTA gasoline, gasoline / LPG and
natural gas engine are designated as shown in the figure.
The sequence of cylinder numbers is given as No.1, No.2 and
No.3 starting from the gear case side.
9Y1210318GEG0006US0
KiSC issued 06, 2009 A
GENERALWG972-E2,DF972-E2,DG972-E2, WSM
G-5
2. GENERAL PRECAUTIONS
• During disassembly, carefully arrange removed parts in a clean
area to prevent confusion later. Screws, bolts and nuts should
be replaced in their original position to prevent reassembly
errors.
• When special tools are required, use KUBOTA genuine special
tools. Special tools which are not frequently used should be
made according to the drawings provided.
• Before disassembling or servicing live wires, make sure to
always disconnect the grounding cable from the battery first.
• Remove oil and dirt from parts before measuring.
• Use only KUBOTA genuine parts for parts replacement to
maintain engine performance and to ensure safety.
• Gaskets and O-rings must be replaced during reassembly.
Apply grease to new O-rings or oil seals before assembling.
• When reassembling external or internal snap rings, position
them so that sharp edge faces against the direction from which
a force is applied.
• Be sure to perform run-in the serviced or reassemble engine.
Do not attempt to give heavy load at once, or serious damage
may result to the engine.
9Y1210318GEG0007US0
(1) Grease
(2) Force
(3) Place the Sharp Edge the Direction
of Force
(A) External Snap Ring
(B) Internal Snap Ring
KiSC issued 06, 2009 A
GENERALWG972-E2,DF972-E2,DG972-E2, WSM
G-6
3. MAINTENANCE CHECK LIST
To maintain long-lasting and safe engine performance, make it a rule to carry out regular inspections by following
the table below. (The schedule applies to an engine in use under normal conditions.)
[WG972-E2, DF972-E2]
Change engine oil and replace oil filter cartridge after the first 50 hours of operation.
* Replace the element after 6 times cleaning.
CAUTION
• When changing or inspecting, be sure to level and stop the engine.
9Y1210318GEG0008US0
Item
Service Interval
Daily Every 50 hrs
Every 100
hrs
Every 200
hrs
Every 1
year
Every 1000
hrs
Every 2
years
Checking engine oil level
Checking and replenish coolant
Checking air cleaner element
Checking LPG tank setting condition
Checking LPG fuel connector
Cleaning air cleaner element
Checking gasoline fuel hose and clamp
bands
Checking LPG fuel hose and clamp bands
LPG fuel check
Checking battery electrolyte level
Cleaning spark plug
Checking fuel filter
Check fan belt tension and damage
Changing engine oil
Replacing oil filter cartridge
Checking LPG tank setting condition
Checking radiator hoses and clamp bands
* Replacing air cleaner element
Replacing gasoline fuel hose, clamp bands
and fuel filter
Cleaning fuel tank inside
Cleaning carburetor
Cleaning water jacket and radiator interior
Replacing spark plug
Checking coolant hose of LPG vaporizer
Checking vacuum lock hose of LPG
vaporizer
Draining tar
Checking valve clearance
Cleaning cylinder head
Checking valve seats
Replacing intake air line
Replacing LPG fuel hose and clamp bands
Replacing coolant hose of LPG vaporizer
Replacing vacuum lock hose of LPG
vaporizer
Checking primary chamber
Checking air tight of secondary chamber
Checking vacuum lock system
Replacing radiator hoses and clamp bands
Replacing battery
Changing radiator coolant (L.L.C.)
KiSC issued 06, 2009 A
GENERALWG972-E2,DF972-E2,DG972-E2, WSM
G-7
[DG972-E2]
Change engine oil and replace oil filter cartridge after the first 50 hours of operation.
* Replace the element after 6 times cleaning.
CAUTION
• When changing or inspecting, be sure to level and stop the engine.
9Y1210318GEG0009US0
Item
Service Interval
Daily Every 50 hrs
Every 100
hrs
Every 200
hrs
Every 1
year
Every 1000
hrs
Every 2
years
Checking engine oil level
Checking and replenish coolant
Checking air cleaner element
Checking fuel line setting condition
Checking fuel connector
Cleaning air cleaner element
Checking fuel hose and clamp bands
Natural gas fuel check
Checking battery electrolyte level
Cleaning spark plug
Checking fuel filter
Check fan belt tension and damage
Changing engine oil
Replacing oil filter cartridge
Checking fuel line setting condition
Checking radiator hoses and clamp bands
* Replacing air cleaner element
Replacing fuel filter
Cleaning gas mixer
Cleaning water jacket and radiator interior
Replacing spark plug
Checking valve clearance
Cleaning cylinder head
Checking valve seats
Replacing intake air line
Replacing fuel hose and clamp bands
Replacing radiator hoses and clamp bands
Replacing battery
Changing radiator coolant (L.L.C.)
KiSC issued 06, 2009 A
GENERALWG972-E2,DF972-E2,DG972-E2, WSM
G-8
4. CHECK AND MAINTENANCE
[1] DAILY CHECK POINTS
Checking Engine Oil Level
1. Level the engine.
2. To check the oil level, draw out the dipstick (1), wipe it clean,
reinsert it, and draw it out again.
Check to see that the oil level lies between the two notches.
3. If the level is too low, add new oil to the specified level.
IMPORTANT
• When using an oil of different maker or viscosity from the
previous one, drain old oil. Never mix two different types of
oil.
• Use the proper SAE Engine oil according to ambient
temperatures.
NOTE
• Be sure to inspect the engine, locating it on a horizontal
place. If placed on gradients, accurately, oil quantity may
not be measured.
• Be sure to keep the oil level between upper and lower limits
of the dipstick. Too much oil may cause a drop in output or
excessive blow-by gas. On the closed breather type engine
in which mist is sucked through port, too much oil may
caused oil hammer. While too little oil, may seize the
engine's rotating and sliding parts.
9Y1210318GEG0010US0
(1) Dipstick
KiSC issued 06, 2009 A
GENERALWG972-E2,DF972-E2,DG972-E2, WSM
G-9
Checking and Replenish Coolant
1. Without recovery tank :
Remove the radiator cap (1) and check to see that the coolant
level is just below the port.
With recovery tank (2) :
Check to see that the coolant level lies between FULL"A" and
LOW "B".
2. If coolant level is too low, check the reason for decreasing
coolant.
(Case 1)
If coolant is decreasing by evaporation, replenish only fresh,
soft water.
(Case 2)
If coolant is decreasing by leak, replenish coolant of the same
manufacture and type in the specified mixture ratio (fresh, soft
water and L.L.C.). If the coolant brand cannot be identified,
drain out all of the remaining coolant and refill with a totally new
brand of coolant mix.
CAUTION
• Do not remove the radiator cap until coolant temperature is
below its boiling point. Then loosen the cap slightly to
relieve any excess pressure before removing the cap
completely.
IMPORTANT
• During filling the coolant, air must be vented from the
engine coolant passages. The air vents by jiggling the
radiator upper and lower hoses.
• Be sure to close the radiator cap securely. If the cap is
loose or improperly closed, coolant may leak out and the
engine could overheat.
• Do not use an antifreeze and scale inhibitor at the same
time.
• Never mix the different type or brand of L.L.C..
9Y1210318GEG0011US0
Checking Air Cleaner Element (If necessary)
1. Remove the dust cup in the air cleaner.
2. Check the dust in the dust cup and the element.
(When reassembling)
• Install the air cleaner dust cup with "TOP" indicated on the rear
of the cup.
9Y1210318GEG0012US0
(1) Radiator Cap
(2) Recovery Tank
A : FULL
B : LOW
(1) Dust Cap
(2) Element
(3) "TOP" Mark
KiSC issued 06, 2009 A
GENERALWG972-E2,DF972-E2,DG972-E2, WSM
G-10
Checking LPG Tank Setting Condition (If necessary)
(DF972-E2)
1. Check the setting condition of LPG fuel tank.
9Y1210318GEG0013US0
Checking Fuel Line Setting Condition (If necessary)
(DG972-E2)
1. Check the setting condition of fuel line.
9Y1210318GEG0014US0
Checking LPG Fuel Connector (DF972-E2)
1. Check the connector of LPG line (hoses and clamps).
9Y1210318GEG0015US0
Checking Fuel Connector (DG972-E2)
1. Check the connector of fuel line (hoses and clamps).
9Y1210318GEG0016US0
[2] CHECK POINTS OF INTIAL 50 HOURS
Changing Engine Oil
CAUTION
• Be sure to stop engine before changing engine oil.
1. Start and warm up the engine for approx. 5 minutes.
2. Place an oil pan underneath the engine.
3. To drain the used oil, remove the drain plug (1) at the bottom of
the engine and drain the oil completely.
4. Screw the drain plug (1).
5. Fill new oil up to upper line on the dipstick (2).
IMPORTANT
• When using an oil of different maker or viscosity from the
previous one, remove all of the old oil.
• Never mix two different types of oil.
• Engine oil should have properties of API classification SH.
• Use the proper SAE Engine Oil according to ambient
temperature.
9Y1210318GEG0017US0
Above 25 °C (77 °F) SAE30 or SAE10W-30
0 °C to 25 °C (32 °F to 77 °F) SAE20 or SAE10W-30
Below 0 °C (32 °F) SAE10W or SAE10W-30
Engine oil capacity 3.4 L0.90 U.S.gals
Tightening torque Drain plug
33 to 37 N·m
3.3 to 3.8 kgf·m
24 to 27 lbf·ft
(1) Drain Plug (2) Dipstick
KiSC issued 06, 2009 A
GENERALWG972-E2,DF972-E2,DG972-E2, WSM
G-11
Replacing Oil Filter Cartridge
CAUTION
• Be sure to stop the engine before changing filter cartridge.
1. Remove the oil filter cartridge (1) with the filter wrench.
2. Apply a slight coat of oil onto the new cartridge gasket.
3. To install the new cartridge, screw it in by hand. Over tightening
may cause deformation of rubber gasket.
4. After the new cartridge has been replaced, the engine oil
normally decrease a little. Thus see that the engine oil does not
leak through the seal and be sure to read the oil level on the
dipstick. Then, replenish the engine oil up to the specified level.
IMPORTANT
• To prevent serious damage to the engine, replacement
element must be highly efficient. Use only a KUBOTA
genuine filter or its equivalent.
9Y1210318GEG0018US0
[3] CHECK POINTS OF EVERY 50 HOURS
Cleaning Air Cleaner Element
1. To clean the element, use clean dry compressed air on the
inside of the element.
Air pressure at the nozzle must be under 210 kPa (2.1 kgf/cm2,
30 psi).
2. If the element is stained with carbon or oil, replace the element.
IMPORTANT
• Make sure the wing bolt for the element is tight enough. If
it is loose, dust and dirt may be sucked, wearing down the
cylinder liner and piston ring earlier and thereby resulting
in poor power output.
• Do not overservice the air cleaner element.
NOTE
• Replace the element once a year or every 6th cleaning.
9Y1210318GEG0019US0
CAUTION
• Stop the engine when attempting the check and replace prescribed below.
• Remember to check the fuel line periodically. The fuel line is subject to wear and aging, fuel may leak out
onto the running engine, causing a fire.
9Y1210318GEG0020US0
Checking Gasoline Fuel Hose and Clamp Bands (WG972-E2,
DF972-E2)
Check the fuel hoses every 50 hours of operation.
1. Since the fuel hose (2) is made of rubber, it ages regardless of
the period of service.
Replace the fuel hose together with the clamp every two years.
2. However, if the fuel hose and clamp are found to be damaged
or deteriorate earlier than two years, then replace or remedy.
3. After the fuel hose and the clamp have been replaced, bleed the
fuel system.
9Y1210318GEG0021US0
(1) Engine Oil Filter Cartridge
(1) Clamp (2) Fuel Hose
KiSC issued 06, 2009 A
GENERALWG972-E2,DF972-E2,DG972-E2, WSM
G-12
Checking LPG Fuel Hose and Clamp Bands (DF972-E2)
IMPORTANT
• Never test for gas leaks with a FLAME.
NOTE
• Check for fuel leakage with soapy water or gas-detector, if
leakage is found, correct leakage or replace the hose.
9Y1210318GEG0022US0
Checking Fuel Hose and Clamp Bands (DG972-E2)
IMPORTANT
• Never test for gas leaks with a FLAME.
NOTE
• Check for fuel leakage with soapy water or gas-detector, if
leakage is found, correct leakage or replace the hose.
9Y1210318GEG0023US0
LPG Fuel Check
1. Open the shut off solenoid valve on the tank.
2. Check for
a) Fuel tank to filter
b) Filter to shut off solenoid valve
c) Shut off solenoid valve to vaporizer
9Y1210318GEG0024US0
Natural Gas Fuel Check
1. Open the shut off solenoid valve on the tank.
2. Check for
a) Fuel source to filter
b) Filter to shut off solenoid valve
c) Shut off solenoid valve to regulator
9Y1210318GEG0025US0
Checking Battery Electrolyte Level
1. Check the battery electrolyte level.
2. If the level is below than lower level line, add the distilled water
to pour level of each cell.
CAUTION
• Never remove the vent plugs while the engine is running.
• Keep electrolyte away from eyes, hands and clothes.
If you are spattered with it, wash it away completely with
water immediately and get medical attention.
• Wear eye protection and rubber gloves when working
around battery.
9Y1210318GEG0026US0
KiSC issued 06, 2009 A
GENERALWG972-E2,DF972-E2,DG972-E2, WSM
G-13
[4] CHECK POINTS OF EVERY 100 HOURS
Cleaning Spark Plug Gap
1. Remove the spark plug, and remove carbon from the electrode
with a wire brush or other tools.
2. Measure the spark plug gap with a feeler gauge, and repair or
replace the plug if the measured gap differs from the factory
specification.
3. Replace the plug if the electrode or the insulator is deformed or
cracked.
4. Tighten the plug with a plug wrench.
9Y1210318GEG0027US0
Checking Fuel Filter
1. Check the fuel filter.
2. If the fuel filter is dirty, clean it or replace it.
CAUTION
• Stop the engine when attempting to check and clean the
fuel filter.
• Gasoline fuel is extremely flammable, so avoid fires.
9Y1210318GEG0028US0
Fan Belt Tension
1. Measure the deflection (A), depressing the belt halfway
between the fan drive pulley and alternator pulley at specified
force 98 N (10 kgf, 22 lbf).
2. If the measurement is not within the factory specifications,
loosen the alternator mounting screws and relocate the
alternator to adjust.
9Y1210318GEG0001US0
Spark plug gap Factory spec. 0.60 to 0.70 mm0.024 to 0.027 in.
Spark plug NGK BKR4E
Tightening torque Spark plug
20 to 24 N·m
2.0 to 2.5 kgf·m
15 to 18 lbf·ft
Deflection (A) Factory spec. 7.0 to 9.0 mm0.28 to 0.35 in.
(A) Deflection
KiSC issued 06, 2009 A
GENERALWG972-E2,DF972-E2,DG972-E2, WSM
G-14
Fan Belt Damage and Wear
1. Check the fan belt for damage.
2. If the fan belt is damaged, replace it.
3. Check if the fan belt is worn and sunk in the pulley groove.
4. If the fan belt is nearly worn out and deeply sunk in the pulley
groove, replace it.
9Y1210318GEG0002US0
[5] CHECK POINTS OF EVERY 200 HOURS
Changing Engine Oil
CAUTION
• Be sure to stop engine before changing engine oil.
1. Start and warm up the engine for approx. 5 minutes.
2. Place an oil pan underneath the engine.
3. To drain the used oil, remove the drain plug (1) at the bottom of
the engine and drain the oil completely.
4. Screw the drain plug (1).
5. Fill new oil up to upper line on the dipstick (2).
IMPORTANT
• When using an oil of different maker or viscosity from the
previous one, remove all of the old oil.
• Never mix two different types of oil.
• Engine oil should have properties of API classification SH.
• Use the proper SAE Engine Oil according to ambient
temperature.
9Y1210318GEG0029US0
(A) Good (B) Bad
Above 25 °C (77 °F) SAE30 or SAE10W-30
0 °C to 25 °C (32 °F to 77 °F) SAE20 or SAE10W-30
Below 0 °C (32 °F) SAE10W or SAE10W-30
Engine oil capacity 3.4 L0.90 U.S.gals
Tightening torque Drain plug
33 to 37 N·m
3.3 to 3.8 kgf·m
24 to 27 lbf·ft
(1) Drain Plug (2) Dipstick
KiSC issued 06, 2009 A
GENERALWG972-E2,DF972-E2,DG972-E2, WSM
G-15
Replacing Engine Oil Filter Cartridge
CAUTION
• Be sure to stop the engine before changing filter cartridge.
1. Remove the oil filter cartridge (1) with the filter wrench.
2. Apply a slight coat of oil onto the new cartridge gasket.
3. To install the new cartridge, screw it in by hand. Over tightening
may cause deformation of rubber gasket.
4. After the new cartridge has been replaced, the engine oil
normally decrease a little. Thus see that the engine oil does not
leak through the seal and be sure to read the oil level on the
dipstick. Then, replenish the engine oil up to the specified level.
IMPORTANT
• To prevent serious damage to the engine, replacement
element must be highly efficient. Use only a KUBOTA
genuine filter or its equivalent.
9Y1210318GEG0030US0
Checking LPG Tank Setting Condition (DF972-E2)
1. Check the setting condition of LGP fuel tank.
9Y1210318GEG0031US0
Checking Fuel Line Setting Condition (DG972-E2)
1. Check the setting condition of fuel line.
9Y1210318GEG0032US0
Checking Radiator Hoses and Clamp Bands
1. Check to see if the radiator hoses are properly fixed every 200
hours of operation or every six months, whichever comes first.
2. If the clamp is loose, apply oil to the threads and retighten it
securely.
3. The coolant hose is made of rubber and tends to age. It must be
replaced every two years. Also replace the clamp and tighten it
securely.
9Y1210318GEG0033US0
[6] CHECK POINTS OF EVERY 1 YEAR
Replacing Air Cleaner Element
1. Remove the dust cup from the air cleaner.
2. After cleaning the dust cup, remove the air cleaner element.
3. Replace the new air cleaner element.
9Y1210318GEG0034US0
Replacing Gasoline Fuel Hose, Clamp Bands and Fuel Filter
(WG972-E2, DF972-E2)
1. Close the fuel tank cock.
2. Replace the fuel filter (1) with a new one.
3. Replace the hose (2) and clamp (3).
9Y1210318GEG0035US0
(1) Engine Oil Filter Cartridge
(1) Upper Hose (2) Lower Hose
(1) Air Cleaner Element
(1) Fuel Filter
(2) Fuel Hose
(3) Clamp
KiSC issued 06, 2009 A
GENERALWG972-E2,DF972-E2,DG972-E2, WSM
G-16
Replacing Fuel Filter (DG972-E2)
1. Close the fuel line.
2. Replace the fuel filter with a new one.
9Y1210318GEG0036US0
Cleaning Fuel Tank Inside (for Gasoline Fuel)
1. Following the unit / machine's operators manual, drain the
gasoline fuel in the fuel tank.
2. Clean the fuel tank inside.
9Y1210318GEG0037US0
Cleaning Carburetor (WG972-E2, DF972-E2)
1. Clean and check for leakage.
2. Check throttle plate for dirt.
9Y1210318GEG0038US0
Cleaning Gas Mixer (DG972-E2)
1. Clean and check for leakage.
2. Check throttle plate for dirt.
9Y1210318GEG0039US0
KiSC issued 06, 2009 A
GENERALWG972-E2,DF972-E2,DG972-E2, WSM
G-17
Cleaning Water Jacket and Radiator Interior
CAUTION
• Do not remove the radiator cap when the engine is hot.
Then loosen cap slightly to the stop to relieve any excess
pressure before removing cap completely.
1. Stop the engine and let cool down.
2. To drain the coolant, open the radiator drain plug (2) and
remove the radiator cap (1). Then radiator cap (1) must be
removed to completely drain the coolant. And open the drain
cock (3) of engine body.
3. After all coolant is drained, close the drain plug.
4. Fill with clean water and cooling system cleaner.
5. Follow directions of the cleaner instruction.
6. After flushing, fill with clean water and anti-freeze until the
coolant level is just below the port. Install the radiator cap (1)
securely.
7. Fill with coolant up to FULL "A" mark on the recovery tank (4).
8. Start and operate the engine for few minutes.
9. Stop the engine and let cool. Check coolant level of recovery
tank (4) and add coolant if necessary.
IMPORTANT
• Do not start engine without coolant.
• Use clean, fresh, soft water and anti-freeze to fill the
radiator and recovery tank.
• When the anti-freeze is mixed with fresh, soft water, the
anti-freeze mixing ratio must be less than 50 %.
• Securely tighten radiator cap. If the cap is loose or
improperly fitted, water may leak out and the engine could
overheat.
9Y1210318GEG0040US0
(1) Radiator Cap
(2) Drain Plug
(3) Drain Cock
(4) Recovery Tank
A : FULL
B : LOW
KiSC issued 06, 2009 A
GENERALWG972-E2,DF972-E2,DG972-E2, WSM
G-18
Anti-Freeze
• There are two types of anti-freeze available: use the permanent
type (PT) for this engine.
• Before adding anti-freeze for the first time, clean the radiator
interior by pouring fresh, soft water and draining it a few times.
• The procedure for mixing water and anti-freeze differs
according to the make of the anti-freeze and the ambient
temperature. Basically, it should be referred to SAE J1034
standard, more specifically also to SAE J814c.
• Mix the anti-freeze with fresh, soft water, and then fill into the
radiator.
IMPORTANT
• When the anti-freeze is mixed with fresh, soft water, the
anti-freeze mixing ratio must be less than 50 %.
* At 1.01 × 100000 Pa (760 mmHg) pressure (atmospheric). A
higher boiling point is obtained by using a radiator pressure cap
which permits the development of pressure within the cooling
system.
NOTE
• The above data represents industrial standards that
necessitate a minimum glycol content in the concentrated
anti-freeze.
• When the coolant level drops due to evaporation, add
fresh, soft water only to keep the anti-freeze mixing ratio
less than 50 %. In case of leakage, add anti-freeze and
fresh, soft water in the specified mixing ratio.
• Anti-freeze absorbs moisture. Keep unused anti-freeze in a
tightly sealed container.
• Do not use radiator cleaning agents when anti-freeze has
been added to the coolant.
(Anti-freeze contains an anti-corrosive agent, which will
react with the radiator cleaning agent forming sludge which
will affect the engine parts.)
9Y1210318GEG0041US0
[7] CHECK POINTS OF EVERY 1000 HOURS
Replacing Spark Plug
1. Disconnect the spark plug cap (1).
2. Remove the spark plug.
3. Replace the new spark plug.
9Y1210318GEG0042US0
Vol %
anti-freeze
Freezing point Boiling point*
°C °F °C °F
40 −24 −11 106 223
50 −37 −35 108 226
Tightening torque Spark plug
20 to 24 N·m
2.0 to 2.5 kgf·m
15 to 18 lbf·ft
(1) Spark Plug Cap
KiSC issued 06, 2009 A
GENERALWG972-E2,DF972-E2,DG972-E2, WSM
G-19
Checking Coolant Hose of LPG Vaporizer (DF972-E2)
1. Check the coolant hoses (1) for damage.
2. If the coolant hose is damaged, replace it.
9Y1210318GEG0043US0
Checking Vacuum Lock Hose of LPG Vaporizer (DF972-E2)
1. Check the vacuum lock hose (1) for damage.
2. If the hose is damaged, replace it.
9Y1210318GEG0044US0
Draining Tar (Vaporizer for DF972-E2)
1. Run the engine until it is warmed up.
2. The shut off solenoid valve is shut and the engine is stopped
naturally.
3. Place an oil pan underneath the drain port.
4. Remove the drain plug (4), and drain tar.
5. Tighten the plug.
NOTE
• Apply a liquid gasket (Three Bond 1104 or equivalent) to
the thread of the plug.
9Y1210318GEG0045US0
(1) Coolant Hoses to Vaporizer
(1) Vacuum Lock Hoses
(1) Vaporizer
(2) Coolant Hose
(3) Wrench
(4) Drain Plug
(5) Liquid Gasket
(6) Joint
KiSC issued 06, 2009 A
GENERALWG972-E2,DF972-E2,DG972-E2, WSM
G-20
Checking Valve Clearance
IMPORTANT
• The valve clearance must be checked and adjusted when
engine is cold.
1. Remove the cylinder head cover and the spark plugs.
2. Align the "1TC" mark (1) on the flywheel and alignment mark (2)
on the rear end plate so that the No. 1 piston comes to the
compression top dead center.
3. Check the following valve clearance marked with " " using a
feeler gauge.
4. If the clearance is not within the factory specifications, adjust
with the adjusting screw.
5. Then turn the flywheel 6.28 rad (360 °), and align the "1TC"
mark (1) on the flywheel and alignment mark (2) on the rear end
plate so that the No. 1 piston comes to the overlap position.
6. Check the following valve clearance marked with " " using a
feeler gauge.
7. If the clearance is not within the factory specifications, adjust
with the adjusting screw.
: When No. 1 piston is at the compression top dead center position.
: When No. 1 piston is at the overlap position.
NOTE
• The sequence of cylinder numbers is given as No. 1, No. 2
and No. 3 starting from the gear case side.
• After adjusting the valve clearance, secure the adjusting
screw with the lock nut.
9Y1210318GEG0046US0
Cleaning Cylinder Head
1. Remove the carbon from cylinder head with a wire brush or their
tools.
NOTE
• Do not scratch the cylinder head with a wire brush.
9Y1210318GEG0047US0
Adjustable Cylinder Location
of Piston
Valve Arrangement
Intake valve Exhaust valve
No. 1
No. 2
No. 3
Intake and exhaust valve
clearance (cold) Factory spec.
0.145 to 0.185 mm
0.00571 to 0.00728 in.
(1) "1TC" Mark
(2) Alignment Mark
A : Gear Case Side
KiSC issued 06, 2009 A
GENERALWG972-E2,DF972-E2,DG972-E2, WSM
G-21
Checking Valve Seats
1. Coat the valve face lightly with prussian blue and put the valve
on its seat to check the contact.
2. If the valve does not seat all the way around the valve seat or
the valve contact is less than 70 %, correct the valve seating as
follows.
3. If the valve contact does not comply with the reference value,
replace the valve or correct the contact of valve seating.
9Y1210318GEG0048US0
[8] CHECK POINTS OF EVERY 2 YEARS
Replacing Intake Air Line
1. Replace the intake hose and the clamps between the air cleaner
and the carburetor or gas mixer.
9Y1210318GEG0049US0
Replacing LPG Fuel Hose and Clamp Bands (DF972-E2)
1. Replace the fuel hose and the clamps.
9Y1210318GEG0050US0
Replacing Fuel Hose and Clamp Bands (DG972-E2)
1. Replace the fuel hose and the clamps.
9Y1210318GEG0051US0
Replacing Coolant Hose of LPG Vaporizer (DF972-E2)
1. Connect the new coolant hose (1) and (2) to the vaporizer (3).
2. Hold the joint of vaporizer upward.
3. The coolant replenished to radiator, and bleed the air from the
vaporizer (3).
9Y1210318GEG0052US0
Valve seat width Factory spec. 2.12 mm0.0835 in.
(1) Correct
(2) Incorrect
(3) Incorrect
(1) Coolant Hose
(2) Coolant Hose
(3) Vaporizer
A : Joint
KiSC issued 06, 2009 A
GENERALWG972-E2,DF972-E2,DG972-E2, WSM
G-22
Replacing Vacuum Lock Hose of LPG Vaporizer (DF972-E2)
1. Connect the new vacuum lock hose (1).
9Y1210318GEG0053US0
Checking Primary Chamber (DF972-E2)
IMPORTANT
• When checking the fuel system after completely
consuming the fuel in piping.
• Treat a seal tape or liquid gasket when install each
connector.
1. Run the engine until is warmed up.
2. Shut a shut off solenoid valve and the engine stopped naturally.
3. Disconnect the plug (1).
4. Set the pressure gauge (2).
5. Open a shut off solenoid valve and the engine is started.
6. Check the pressure.
7. If the pressure is not within the factory specification, replace the
vaporizer.
9Y1210318GEG0054US0
Checking Air Tight of Secondary Chamber (DF972-E2)
1. Disconnect the vapor hose (1) from the mixer side.
2. Blow a breath lightly or compressed air (9.8 kPa, 0.10 kgf/cm2,
1.4 psi).
3. Make sure that there is no air leak.
4. If there is a leakage, replace the vaporizer.
9Y1210318GEG0055US0
Checking Vacuum Lock System (DF972-E2)
1. After warming up, and set the low idling speed.
2. Disconnect the vacuum lock hose (1), and close the joint
manifold by finger.
3. Make sure that the engine stops.
9Y1210318GEG0056US0
(1) Vacuum Lock Hose
Pressure Factory spec.
30 to 34 kPa
0.30 to 0.35 kgf/cm2
4.3 to 4.9 psi
(1) Plug (2) Pressure Gauge
(1) Vapor Hose
(1) Vacuum Lock Hose (2) Joint
KiSC issued 06, 2009 A
GENERALWG972-E2,DF972-E2,DG972-E2, WSM
G-23
Replacing Radiator Hoses and Clamp Bands
CAUTION
• Do not remove the radiator cap when the engine is hot.
Then loosen cap slightly to the stop to relieve any excess
pressure before removing cap completely.
1. Drain the coolant.
2. Loosen the clamp bands.
3. Remove the upper hose (1) and lower hose (2).
4. Replace new upper / lower hose (1), (2) and clamp bands.
5. Tighten the clamp bands.
6. Fill with clean water and anti-freeze until the coolant level is just
below the port. Install the radiator cap securely.
9Y1210318GEG0057US0
Replacing Battery
CAUTION
• When the battery is being activated, hydrogen and oxygen
gases in the battery are extremely explosive. Keep open
sparks and flames away from the battery at all times,
especially when charging the battery.
• When charging battery, remove battery vent plugs.
• When disconnecting the cable from the battery, start with
the negative terminal first. When connecting the cable to
the battery, start with the positive terminal first.
• Never check battery charge by placing a metal object
across the posts.
1. Disconnect the negative terminal and positive terminal.
2. Remove the battery holder.
3. Remove the used battery.
4. Replace the new battery.
5. Tighten the battery holder.
6. Connect the positive terminal.
7. Connect the negative terminal.
9Y1210318GEG0058US0
(1) Upper Hose (2) Lower Hose
KiSC issued 06, 2009 A
GENERALWG972-E2,DF972-E2,DG972-E2, WSM
G-24
Changing Radiator Coolant (L.L.C.)
CAUTION
• Do not remove the radiator cap when the engine is hot.
Then loosen cap slightly to the stop to relieve any excess
pressure before removing cap completely.
1. Stop the engine and let cool down.
2. To drain the coolant, open the radiator drain plug (2) and
remove the radiator cap (1). Then radiator (1) must be removed
to completely drain the coolant. And open the drain cock of
engine body.
3. After all coolant is drained, close the drain plug.
4. Fill with clean water and cooling system cleaner.
5. Follow directions of the cleaner instruction.
6. After flushing, fill with clean water and anti-freeze until the
coolant level is just below the port. Install the radiator cap (1)
securely.
7. Fill with coolant up to FULL"A" mark on the recovery tank (3).
8. Start and operate the engine for few minutes.
9. Stop the engine and let cool. Check coolant level of radiator and
recovery tank (3) and add coolant if necessary.
IMPORTANT
• Do not start engine without coolant.
• Use clean, fresh, soft water and anti-freeze to fill the
radiator and recovery tank.
• When the anti-freeze is mixed with fresh, soft water, the
anti-freeze mixing ratio must be less than 50 %.
• Securely tighten radiator cap. If the cap is loose or
improperly fitted, water may leak out and the engine could
overheat.
(To be continued)
(1) Radiator Cap
(2) Drain Plug
(3) Recovery Tank
A : Full
B : Low
KiSC issued 06, 2009 A
GENERALWG972-E2,DF972-E2,DG972-E2, WSM
G-25
(Continued)
(Anti-freeze)
• There are two types of anti-freeze available; use the permanent
type (PT) for this engine.
• Before adding anti-freeze for the first time, clean the radiator
interior by pouring fresh, soft water and drain it a few times.
• The procedure for mixing water and anti-freeze differs
according to the make of the anti-freeze and the ambient
temperature. Basically, it should be referred to SAE J1034
standard, more specifically also to SAE J814c.
• Mix the anti-freeze with fresh, soft water, and then fill into the
radiator.
IMPORTANT
• When the anti-freeze is mixed with fresh, soft water, and
anti-freeze mixing ratio must be less than 50 %.
* At 1.01 x 100000 Pa (760 mmHg) pressure (atmospheric). A
higher boiling point is obtained by using a radiator pressure cap
which permits the development of pressure within the cooling
system.
NOTE
• The above data represents industrial standards that
necessitate a minimum glycol content in the concentrated
anti-freeze.
• When the coolant level drops due to evaporation, add
fresh, soft water only to keep the anti-freeze mixing ratio
less than 50 %. In case of leakage, add anti-freeze and
fresh, soft water in the specified mixing ratio.
• Anti-freeze absorbs moisture. Keep unused anti-freeze in a
tightly sealed container.
• Do not use radiator cleaning agents when anti-freeze has
been added to the coolant.
(Anti-freeze contains an anti-corrosive agent, which will
react with the radiator cleaning agent forming sludge which
will affect the engine parts.)
9Y1210318GEG0059US0
Vol %
anti-freeze
Freezing point Boiling point*
°C °F °C °F
40 −24 −11 106 223
50 −37 −35 108 226
KiSC issued 06, 2009 A
GENERALWG972-E2,DF972-E2,DG972-E2, WSM
G-26
5. SPECIAL TOOLS
Timing Light
Application
• Use to adjust the ignition timing.
WSM000001GEG0089US0
Compression Tester
Code No.
• 07909-30251
Application
• Use to measure gasoline engine compression and diagnose the
engine for a major overhaul.
WSM000001GEG0088US0
Oil Pressure Tester
Code No.
• 07916-32032
Application
• Use to measure lubricating oil pressure.
WSM000001GEG0015US0
Pressure Gauge
Specification
• 98 kPa (1.0 kgf/cm2, 14 psi)
Application
• Check the pressure of vaporizer.
WSM000001GEG0090US0
(1) Gauge
(2) Cable
(3) Threaded Joint
(4) Adaptor 1
(5) Adaptor 2
(6) Adaptor 3
(7) Adaptor 4
(8) Adaptor 5
KiSC issued 06, 2009 A
GENERALWG972-E2,DF972-E2,DG972-E2, WSM
G-27
Valve Guide Replacing Tool
Application
• Use to press out and press fit the valve guide.
9Y1210318GEG0060US0
Bushing Replacing Tool
Application
• Use to press out and to press fit the bushing.
[For small end bushing]
[For idle gear bushing]
9Y1210318GEG0061US0
A 200 mm (7.87 in.)
B 80 mm (3.1 in.)
C 40 mm (1.6 in.)
D 20 mm dia. (0.79 in. dia.)
E 9.960 to 9.980 mm dia. (0.3922 to 0.3929 in. dia.)
F 5.50 to 5.70 mm dia. (0.217 to 0.224 in. dia.)
G 15 mm (0.59 in.)
H 6.00 to 6.10 mm dia. (0.237 to 0.240 in. dia.)
I 5 mm (0.2 in.)
J 18 mm dia. (0.71 in. dia.)
K 10.6 to 10.7 mm dia. (0.418 to 0.421 in. dia.)
L 7 mm (0.3 in.)
C1 Chamfer 1.0 mm (0.039 in.)
C2 Chamfer 2.0 mm (0.079 in.)
C0.3 Chamfer 0.3 mm (0.01 in.)
A 145 mm (5.71 in.)
B 20 mm (0.79 in.)
C 100 mm (3.94 in.)
D 19.90 to 19.95 mm (0.7835 to 0.7854 in.)
E 21.90 to 21.95 mm dia. (0.8622 to 0.8641 in. dia.)
F 25 mm (0.98 in.)
a 6.3 µm (250 µin.)
b 6.3 µm (250 µin.)
A 150 mm (5.91 in.)
B 20 mm (0.79 in.)
C 100 mm (3.94 in.)
D 19.90 to 19.95 mm (0.7835 to 0.7854 in.)
E 21.90 to 21.95 mm dia. (0.8622 to 0.8641 in. dia.)
F 25 mm (0.98 in.)
a 6.3 µm (250 µin.)
b 6.3 µm (250 µin.)
KiSC issued 06, 2009 A
GENERALWG972-E2,DF972-E2,DG972-E2, WSM
G-28
Flywheel Stopper
Application
• Use to loosen and tighten the flywheel screw.
9Y1210318GEG0062US0
Crankshaft Bearing 1 Replacing Tool
Application
• Use to press out and press fit the crankshaft bearing 1.
[Press Out]
[Press Fit]
9Y1210318GEG0063US0
A 20 mm (0.79 in.)
B 15 mm (0.59 in.)
C 10 mm dia. (0.39 in. dia.)
D 30 mm (1.2 in.)
E 8 mm (0.3 in.)
F 200 mm (7.87 in.)
A 135 mm (5.31 in.)
B 72 mm (2.8 in.)
C 40 mm radius (1.6 in. radius)
D 10 mm (0.39 in.)
E 22 mm (0.87 in.)
F 20 mm dia. (0.79 in. dia.)
G 47.90 to 47.95 mm dia. (1.886 to 1.887 in. dia.)
H 43.90 to 43.95 mm dia. (1.729 to 1.730 in. dia.)
A 130 mm (5.12 in.)
B 72 mm (2.8 in.)
C 40 mm radius (1.6 in. radius)
D 9 mm (0.4 in.)
E 24 mm (0.94 in.)
F 20 mm (0.79 in.)
G 68 mm dia. (2.7 in. dia.)
H 43.90 to 43.95 mm dia. (1.729 to 1.730 in. dia.)
KiSC issued 06, 2009 A
GENERALWG972-E2,DF972-E2,DG972-E2, WSM
G-29
Valve Stem Seal Replacing Tool
Application
• Use to press fit the valve stem seal.
9Y1210318GEG0064US0
A 17.5 mm dia. (0.689 in. dia.)
B 13.7 to 13.9 mm dia. (0.540 to 0.547 in. dia.)
C 11.0 to 11.2 mm dia. (0.433 to 0.440 in. dia.)
D 75 mm (3.0 in.)
E 60 mm (2.4 in.)
F 45 mm (1.8 in.)
G 11.5 to 11.6 mm (0.453 to 0.456 in.)
H 8.5 mm (0.33 in.)
I 37.5 mm (1.48 in.)
J 6 mm dia. (0.2 in. dia.)
K 6 mm dia. (0.2 in. dia.)
L R 30
M 26 mm dia. (1.0 in. dia.)
a Chamfer 0.3 mm (0.01 in.)
b Chamfer 0.4 mm (0.02 in.)
c Chamfer 0.2 mm (0.008 in.)
KiSC issued 06, 2009 A
GENERALWG972-E2,DF972-E2,DG972-E2, WSM
G-30
Electronic Governor Service Tool (WG972-E2, DF972-E2)
NOTE
• Many applications are delivered pre-configured, calibrated,
and tuned. These units do not require the use of the Service
Tool.
The Service Tool software is used to troubleshoot the electronic
governor.
The Service Tool software resides on a PC (Personal computer)
and communicates to the electronic governor through connector
pins 4 and 6. An external RS-232 transceiver is necessary to make
communications possible with the Woodward L-Series Service
Tool.
The following hardware is required to work with the L-Series
control : communication port, and Windows 95 / 98 / 2000 / NT / Me
/ XP as the operating system.
• PC-compatible laptop or desktop computer with at least one
available serial communications port, and Windows 95 / 98 /
2000 / NT / Me / XP as the operating system.
• Datalink harness
A connectivity kit (Woodward No. 8923-1061) can be purchased
from Woodward to accomplish this.
In addition to the hardware, the following are the distributions of
tool software needed to communicate with the control :
• Woodward part number 9927-1222, L-Series Service Tool.
CAUTION
• There is a potential for serial port damage when
communicating with the L-Series control. This is caused by
a difference in AC voltage between neutral and earth
ground. If the PC RS-232 port ground is referenced to AC
neutral, and the L-Series control is referenced to battery
ground (AC earth ground), a large amount of current can be
experienced. To avoid this situation, we strongly
recommend placing an isolation transformer between the
AC outlet and the PC.
9Y1210318GEG0065US0
(1) Connectivity Kit A : To Actuator
B : From Engine Control Harness
C : To Personal Computer
KiSC issued 06, 2009 A
1 ENGINE
KiSC issued 06, 2009 A
CONTENTS
1. ENGINE BODY........................................................................................................................... 1-M1
[1] CYLINDER BLOCK .............................................................................................................. 1-M1
[2] HALF-FLOATING HEAD COVER ........................................................................................ 1-M1
[3] CYLINDER HEAD ................................................................................................................ 1-M2
[4] CRANKSHAFT ..................................................................................................................... 1-M2
[5] PISTON AND PISTON RING ............................................................................................... 1-M3
[6] OIL PAN ............................................................................................................................... 1-M3
[7] CONNECTING ROD ............................................................................................................ 1-M4
[8] CAMSHAFT.......................................................................................................................... 1-M4
[9] FUEL CAMSHAFT................................................................................................................ 1-M4
[10]ROCKER ARM ASSEMBLY................................................................................................. 1-M5
[11]INLET AND EXHAUST VALVES.......................................................................................... 1-M5
[12]FLYWHEEL .......................................................................................................................... 1-M5
[13]CLOSED BREATHER .......................................................................................................... 1-M6
2. LUBRICATING SYSTEM............................................................................................................ 1-M7
[1] GENERAL ............................................................................................................................ 1-M7
[2] OIL PUMP ............................................................................................................................ 1-M8
[3] RELIEF VALVE .................................................................................................................... 1-M8
[4] OIL FILTER CARTRIDGE .................................................................................................... 1-M8
[5] OIL PRESSURE SWITCH.................................................................................................... 1-M9
3. COOLING SYSTEM ................................................................................................................. 1-M10
[1] GENERAL .......................................................................................................................... 1-M10
[2] COOLING FIN .................................................................................................................... 1-M10
[3] WATER PUMP ................................................................................................................... 1-M10
[4] THERMOSTAT................................................................................................................... 1-M11
[5] RADIATOR ......................................................................................................................... 1-M11
[6] RADIATOR CAP................................................................................................................. 1-M12
[7] VAPORIZER (DF972-E2) ................................................................................................... 1-M12
4. FUEL SYSTEM......................................................................................................................... 1-M13
[1] GENERAL .......................................................................................................................... 1-M13
(1) WG972-E2, DF972-E2 ................................................................................................. 1-M13
(2) DG972-E2..................................................................................................................... 1-M14
[2] CARBURETOR AND GAS MIXER..................................................................................... 1-M15
(1) Carburetor (WG972-E2) ............................................................................................... 1-M15
(2) Carburetor (DF972-E2)................................................................................................. 1-M16
(3) Gas Mixer (DG972-E2)................................................................................................. 1-M17
[3] VAPORIZER (DF972-E2) ................................................................................................... 1-M17
[4] REGULATOR (DG972-E2)................................................................................................. 1-M20
[5] GOVERNOR....................................................................................................................... 1-M21
[6] INLET MANIFOLD.............................................................................................................. 1-M21
[7] FUEL FILTER (FOR GASOLINE LINE).............................................................................. 1-M22
[8] ELECTRO MAGNETIC FUEL FEED PUMP (FOR GASOLINE LINE) ............................... 1-M22
5. IGNITION SYSTEM.................................................................................................................. 1-M23
[1] DEGITAL IGNITION SYSTEM ........................................................................................... 1-M23
6. ELECTRICAL SYSTEM............................................................................................................ 1-M24
[1] STARTING SYSTEM.......................................................................................................... 1-M24
[2] CHARGING SYSTEM ........................................................................................................ 1-M25
[3] SOLENOID ......................................................................................................................... 1-M28
7. ELECTRONIC GOVERNOR..................................................................................................... 1-M29
MECHANISM
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-M1
1. ENGINE BODY
[1] CYLINDER BLOCK
The engine has a high durability tunnel-type cylinder
block in which the crank bearing component is a
constructed body. Furthermore, liner less type, allow
effective cooling, less distortion, and greater wear
resistance. The noise level is reduced to a minimum
because each cylinder has its own chamber.
To increase the rigidity of the cylinder block, parts of
engine block which support main bearing case has
thicker rib for additional rigidness to improve noise and
vibration.
9Y1210318ENM0001US0
[2] HALF-FLOATING HEAD COVER
The rubber packing is fitting in to maintain the head
cover 0.5 mm (0.02 in.) or so off the cylinder head. This
arrangement helps reduce noise coming from the
cylinder head.
9Y1210318ENM0002US0
(1) Cylinder Head Cover (2) Rubber Packing
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-M2
[3] CYLINDER HEAD
Intake and Exhaust Port
The cross-flow type intake / exhaust ports, which
lower the heat conduction from the exhaust port to the
intake port. The low heat conduction keeps the intake air
from being heated and expanded by the exhaust gas.
9Y1210318ENM0003US0
Combustion System
The Spark Ignition type combustion chamber,
compactly placed on top of the piston head, successfully
reduces emissions. To ensure even more reliable
emission life, the intake / exhaust valve seats are fitted
with special heat resistant stellite alloys.
9Y1210318ENM0004US0
[4] CRANKSHAFT
The crankshaft with the connecting rod converts the
reciprocating motion of the piston into rotating motion.
The crankshaft (2) has oil passages drilled so that oil can
flow from the main bearings to the crank pin bearings.
The front journal is supported by a sleeve type
bearing (crankshaft bearing 1) (1), the intermediate
journal by a split type (crankshaft bearing 3) (4), and the
rear by a split type (crankshaft bearing 2) (6) with thrust
bearings (5).
9Y1210318ENM0005US0
(1) Intake Port (2) Exhaust Port
(1) Valve
(2) Valve Seat
(3) Main Combustion Chamber
(4) Piston
(5) Spark Plug
(1) Crankshaft Bearing 1
(2) Crankshaft
(3) Feather Key
(4) Crankshaft Bearing 3
(5) Thrust Bearing
(6) Crankshaft Bearing 2
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-M3
[5] PISTON AND PISTON RING
Piston and Piston Ring
Expansion Control Piston:
The thermal expansion is suppressed to the
minimum by the adoption of the strut (5). The piston
head has the combustion chamber (1) with the concave
of bathtub shaped type.
Top Ring:
Barrel-faced type has an ideal shape in terms of
lubrication theory in order to prevent abnormal wear due
to edge loading at the time of initial running-in, and it is
very effective in prevention of blow-by.
Second Ring:
Barrel-faced type has an ideal shape in terms of
lubrication theory in order to prevent abnormal wear due
to edge loading at the time of initial running-in, and it is
very effective in prevention of blow-by.
Oil Ring:
Oil ring consists of three steel components, that is
upper and lower rails and one spacer being held
between two rails. This function is particularly effective in
preventing oil-up because of high boost at the time of
engine coasting.
9Y1210318ENM0006US0
Piston Skirt
Piston's skirt is coated with molybdenum
disulfide , which reduces the piston slap noise and
thus the entire operating noise.
Molybdenum disulfide (MoS2)
The molybdenum disulfide serves as a solid
lubricant, like a Graphite or Teflon. This material helps
resist metal wears even with little lube oil.
9Y1210318ENM0007US0
[6] OIL PAN
The oil pan is expanded under the gear case.
Therefore, the height of the engine can be lowered more
than so far while securing a necessary amount of oil.
9Y1210318ENM0008US0
(1) Combustion Chamber
(2) Top Ring
(3) Second Ring
(4) Oil Ring
(5) Strut
(1) Molybdenum Disulfide
(1) Gear Case
(2) Oil Pan
(3) Crank Case
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-M4
[7] CONNECTING ROD
The connecting rod (2) is used to connect the piston
with the crankshaft. The big end of the connecting rod
has a crankpin bearing (3) (split type) and the small end
has a small end bushing (1) (solid type).
9Y1210318ENM0009US0
[8] CAMSHAFT
The camshaft (1) is made of special cast iron, and
the journal and cam sections are chilled to resist wear.
The cams on the camshaft cause the intake and
exhaust valves to open as the camshaft rotates. The
bearing and journals are force-lubricated.
9Y1210318ENM0010US0
[9] FUEL CAMSHAFT
The camshaft (10) is equipped with steel ball (2) to
control the governor.
Power can be taken out from this shaft. (Side PTO).
9Y1210318ENM0011US0
(1) Small End Bushing
(2) Connecting Rod
(3) Crankpin Bearing
(4) Connecting Rod Cap
(5) Connecting Rod Screw
(1) Camshaft
(2) Feather Key
(3) Camshaft Stopper
(4) Cam Gear
(1) Injection Pump Gear
(2) Steel Ball
(3) Governor Sleeve
(4) Steel Ball
(5) Governor Ball Case
(6) Governor Sleeve Snap Ring
(7) Stopper
(8) Ball Bearing
(9) Feather key
(10) Fuel Camshaft
(11) Ball Bearing
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-M5
[10] ROCKER ARM ASSEMBLY
The rocker arm assembly includes the rocker arms
(2) and adjusting screws (1), the end of which rests on
the push rods, rocker arm brackets (4) and rocker arm
shaft (3).
The rocker arms swing and transmits the
reciprocating motion of the push rods to the inlet and
exhaust valves to open and close them.
9Y1210318ENM0012US0
[11] INLET AND EXHAUST VALVES
The valve and its guide for the inlet are different from
those for the exhaust.
Other parts, such as the spring (4), spring retainer
(3), collet (2), stem seal (5), and cap (1) are the same for
both the inlet and exhaust.
9Y1210318ENM0013US0
[12] FLYWHEEL
The flywheel (2) is connected with the crankshaft (1),
it stores the rotating force in the combustion stroke as
inertial energy to rotate the crankshaft smoothly.
The flywheel periphery is provided with marks
showing fuel injection timing and top dead center.
The flywheel has gear teeth around its outer rim,
which mesh with the drive pinion of the starter.
9Y1210318ENM0014US0
(1) Adjusting Screw
(2) Rocker Arm
(3) Rocker Arm Shaft
(4) Rocker Arm Bracket
(1) Valve Cap
(2) Collet
(3) Spring Retainer
(4) Spring
(5) Stem Seal
(6) Valve Guide
(7) Inlet Valve
(8) Exhaust Valve
(1) Crankshaft
(2) Flywheel
(3) Flywheel Mounting Screw
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-M6
[13] CLOSED BREATHER
Blow-by gas (a) from crankcase is deoiled in the
breather assembly (3) and sends to the air cleaner
flange (2) where the blow-by gas (a) is mixed with the
intake air (b).
9Y1210318ENM0015US0
(1) Breather Hose
(2) Air Cleaner Flange
(3) Breather Assembly
(a) Blow-by Gas
(b) Intake Air
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-M7
2. LUBRICATING SYSTEM
[1] GENERAL
The lubricating system consists of an oil strainer, an oil pump, a relief valve, an oil filter cartridge and an oil
pressure switch. The oil pump sucks the lubricating oil in the oil pan through the strainer and sends it to the oil filter
cartridge, where the oil is further filtered.
The filtered oil is forced to the crankshaft, the connecting rods, the idle gear, the camshaft and the rocker arm
shaft through the oil passage in the cylinder block and the shafts to lubricate the bearings.
Some oil, splashed by the crankshaft or thrown off from the bearings, lubricates other engine parts: the pistons,
the cylinder walls, the piston pins, the tappets, the push rods, the timing gears, and the inlet and exhaust valves.
9Y1210318ENM0016US0
(A) Piston
(B) Rocker Arm and Rocker
Arm Shaft
(C) Camshaft
(D) Oil Filter Cartridge and
Relief Valve
(E) Oil Strainer (F) Oil Pump
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-M8
[2] OIL PUMP
The oil pump is a trochoid pump, whose rotors have
trochoid lobes. The inner rotor (2) has 4 lobes and the
outer rotor (4) has 5 lobes, and they are eccentrically
engaged with each other. The inner rotor, which is driven
by the crankshaft through the gears, rotates the outer
rotor in the same direction, varying the space between
the lobes.
While the rotors rotate from (A) to (B), the space
leading to the inlet port increases, which causes the
vacuum to suck in the oil from the inlet port.
When the rotors rotate to (C), the space between
both rotors switches from the inlet port to the outlet port.
At (D), the space decreases and the sucked oil is
discharged from the outlet port.
9Y1210318ENM0017US0
[3] RELIEF VALVE
The relief valve prevents the damage to the
lubricating system due to the high pressure of the oil.
This relief valve is a ball direct acting type, and is
best suited for low pressures.
When the pressure of the oil, forced by the pump,
exceeds the specified value, the oil pushes back the ball
(2) and escapes to the oil pan.
9Y1210318ENM0018US0
[4] OIL FILTER CARTRIDGE
After lubricating, the lubricating oil brings back
various particles of grit and dirt to the oil pan. Those
particles and the impurities in the lubricating oil can
cause wear or seizure of the engine parts. It may also
impair the physical and chemical properties of the oil
itself.
The lubricating oil which is force-fed by the pump, is
filtered by the filter cartridge with the filter element (2).
When the filter element accumulates on excessive
amount of dirt and the oil pressure in the inlet line builds
up by 98 kPa (1.0 kgf/cm2, 14 psi) more than the outlet
line, the bypass valve (1) opens to allow the oil to flow
from the inlet into the outlet line, bypassing the filter
element.
9Y1210318ENM0019US0
(1) Inlet Port
(2) Inner Rotor
(3) Outlet Port
(4) Outer Rotor
(1) Spring
(2) Ball
(3) Valve Seat
(1) Bypass Valve (2) Filter Element
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-M9
[5] OIL PRESSURE SWITCH
The oil pressure switch is mounted on the cylinder
block and is led to the lubricating oil passage.
When the oil pressure falls below the specified value,
the oil pressure warning lamp lights.
9Y1210318ENM0020US0
(1) Terminal
(2) Insulator
(3) Spring
(4) Rubber Gasket
(5) Contact Rivet
(6) Contact
(7) Oil Switch Body
[A] At the proper oil pressure
[B] At lower oil pressure, 50
kPa (0.5kgf/cm2, 7 psi) or
less
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-M10
3. COOLING SYSTEM
[1] GENERAL
The cooling system consists of a radiator (1), a
centrifugal water pump (4), a suction fan (2) and a
thermostat (3).
The coolant is cooled through the radiator core, and
the fan behind the radiator pulls the cooling air through
the core to improve cooling.
The water pump sucks the coolant from the radiator
or from the cylinder head and forces it into the cylinder
block.
The thermostat opens or closes according to the
coolant temperature, to allow the coolant to flow from the
cylinder block to the radiator while open, or only to the
water pump while closed.
9Y1210318ENM0021US0
[2] COOLING FIN
The cooling fin is set up around the oil passage in the
gear case.
Therefore, the temperature of oil is decreased by the
wind generated by the cooling fan.
9Y1210318ENM0022US0
[3] WATER PUMP
The water pump is driven by the crankshaft and a V
belt. The rotating impeller (4) in the water pump sucks
the coolant from the radiator and sends it into the water
jacket in the cylinder block.
The mechanical seal (3) prevents the water from
entering the bearing unit (1).
9Y1210318ENM0023US0
Thermostat's valve
opening temperature
Factory
spec.
69.5 to 72.5 °C
157.1 to 162.5 °F
(1) Radiator
(2) Cooling Fan
(3) Thermostat
(4) Water Pump
(5) Cylinder Head
(6) Cylinder Block
(1) Cooling Fin
(1) Bearing Unit
(2) Water Pump Body
(3) Mechanical Seal
(4) Impeller
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-M11
[4] THERMOSTAT
The thermostat is of the wax pellet type.
The thermostat controls the flow of the coolant to the
radiator to keep the proper temperature.
The case, which serves as a valve seat, has a
spindle inserted in the pellet (3) which is installed to the
valve (2). The spindle is covered with the synthetic
rubber (5) in the pellet.
The wax is charged between the pellet and the
rubber.
At low temperature (lower than 71 °C (160 °F))
The valve (2) is seated by the spring (7) and the
coolant circulates in the engine through the water return
hose without running into the radiator. Only the air in the
water jacket escapes to the radiator through the leak
hole of the thermostat.
At high temperature (higher than 85 °C (185 °F))
As the coolant temperature rises, the wax in the
pellet (3) turns liquid and expands, repelling the spindle,
which causes the pellet to lower. The valve (2) opens to
send the coolant to the radiator.
9Y1210318ENM0024US0
[5] RADIATOR
The radiator core consists of coolant carrying tubes
(1) and fins (2) meeting at a right angle with the tubes.
The fin is a louverless, corrugated type which is light in
weight, high in heat exchange ratio and less apt to clog.
The coolant in the tubes is cooled by the air flowing
through the tube walls and fins.
9Y1210318ENM0025US0
(1) Seat
(2) Valve
(3) Pellet
(4) Spindle
(5) Synthetic Rubber(6)Wax
(Solid)
(7) Spring
(8) Wax (liquid)
(1) Tube
(2) Fin
A : Cooling Air
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-M12
[6] RADIATOR CAP
The pressure type radiator cap prevents differences
in pressure between the inside and the outside of the
radiator from deforming the radiator.
When the coolant temperature rises and the
pressure in the radiator increases above the specified
pressure, the pressure valve (1) opens to reduce the
internal pressure.
When the coolant temperature falls and a vacuum
forms in the radiator, the vacuum valve (2) opens to
introduce the air into the radiator.
9Y1210318ENM0026US0
[7] VAPORIZER (DF972-E2)
When evaporating by primary chamber of vaporizer
liquid LPG needs the evaporation heat.
This vaporizer installs the water jacket, throws the
coolant of engine, heats primary chamber, promotes
evaporation, and prevents valves being frozen.
9Y1210318ENM0027US0
(1) Pressure Valve (Opening
pressure 88 kPa
(0.90 kgf/cm2, 13 psi))
(2) Vacuum Valve
(1) Vaporizer
(2) Hot Coolant In
(3) Hot Coolant Out
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-M13
4. FUEL SYSTEM
[1] GENERAL
(1) WG972-E2, DF972-E2
WG972-E2:
The fuel is fed from the gasoline tank (6) through the fuel filter (4) to the WG carburetor (1) by the fuel feed pump
(3).
DF972-E2:
This fuel system has 2 ways. Gasoline fuel is the same as WG972-E2.
For LPG fuel, the liquid fuel stored in the LPG tank (14) is sent to vaporizer (10) by pressure in the gaseous phase
in the tank through the LPG filter (12) and LPG shut off solenoid valve (11).
The liquid fuel is evaporated in vaporizer and is sent to the DF carburetor (8) as a gaseous fuel of gas pressure
near the atmospheric pressure. The DF carburetor (8) mixes the gas and air is supplied in the cylinder.
9Y1210318ENM0028US0
(1) WG Carburetor
(2) Gasoline Cut Off Solenoid
(3) Fuel Feed Pump
(4) Fuel Filter
(5) Gasoline Cock*
(6) Gasoline Tank*
(7) LPG Cut Off Solenoid
(8) DF Carburetor
(9) Vapor Hose*
(10) Vaporizer
(11) LPG Shut Off Solenoid Valve*
(12) LPG Filter*
(13) LPG Manual Valve*
(14) LPG Tank*
(15) Vacuum Hose*
(16) Coolant Hose*
(a) Gasoline Line
(b) Gaseous Propane Line
(c) Liquid Propane Line
(d) Vacuum Line
(e) Hot Coolant Out Line
(f) Hot Coolant In Line
[A] WG972-E2
[B] DF972-E2
Component Marked * Is Not
Provided by KUBOTA
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-M14
(2) DG972-E2
DG972-E2 :
Natural gas is sent from the gas source through the fuel filter (5), the shut off solenoid valve (4), and the gas
regulator (3) to the gas mixer (1), and mixed with air.
Then, mixture gas is sent to the cylinder by negative pressure of the suction stroke.
9Y1210318ENM0029US0
(1) Gas Mixer
(2) Gas Hose
(3) Gas Regulator
(4) Shut Off Solenoid Valve
(5) Fuel Filter
(6) Gas Hose
(a) Air Vent
(b) Fuel Line
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-M15
[2] CARBURETOR AND GAS MIXER
(1) Carburetor (WG972-E2)
Designed for general purpose use, this carburetor provides engines with the ideal fuel-air mixture for all speed
ranges.
1) Float Chamber
When the gasoline in the fuel tank flows into the float chamber (17), the float (16) rises and, when a predetermined
amount of gasoline is in the chamber, it pushes the needle valve (6) against the valve seat (5) to stop additional
gasoline from entering through the inlet port (4). As the gasoline is consumed, the float goes down and more gasoline
is led into the chamber to maintain a constant distance between the main nozzle (13) and the level of the gasoline.
2) Starting System
To start an engine in cold weather, the fuel-air mixture must be richer than normal. A choke valve (3) controlled
by the choke lever (1) is provided to enrich the mixture.
As the choke valve is closed, the air supply is restricted to make the mixture rich. This rich mixture is then supplied
to the intake manifold to facilitate starting.
3) Slow System
When the throttle valve (12) closes, air that flows into the cylinder passes along the valve at a high speed. As a
result, a negative pressure is crated in the pilot outlet (19) which has an outlet port in the inner wall. This causes
gasoline in the main nozzle (13) to flow through the pilot jet (25) to be sucked into the cylinder. Air that enters from
the slow air jet (22) is mixed with gasoline in the pilot jet (25), atomized in an appropriate condition, sprayed from the
pilot outlet (19) and sucked into the cylinder through the main passage. The slow speed of the engine is controlled by
changing the jet area with the pilot jet (25).
4) Main Carburetor System
The speed of air that flows into the cylinder increases when it passes the venturi (11), and the negative pressure
increase as a result at the tip of the main nozzle (13). The negative pressure causes the gasoline in the float chamber
(17) to flow through the main jet (21) and to be sucked into the main nozzle (13). Air which flows from the main air jet
(23) into the bleeder hole (14) of the main nozzle (13) is mixed with gasoline, atomized in an appropriate condition,
then sprayed from the nozzle tip to the venturi (11) and sucked with the main air into the cylinder.
9Y1210318ENM0030US0
(1) Choke Lever
(2) Carburetor Body
(3) Choke Valve
(4) Inlet Port
(5) Valve Seat
(6) Needle Valve
(7) Float Pin
(8) Earth Cord
(9) Solenoid Valve Assembly
(10) Throttle Shaft
(11) Venturi
(12) Throttle Valve
(13) Main Nozzle
(14) Bleeder Hole
(15) Float Chamber Gasket
(16) Float
(17) Float Chamber
(18) Chamber Set Plug
(19) Pilot Outlet
(20) Pilot Screw
(21) Main Jet
(22) Slow Air Jet
(23) Main Air Jet
(24) Throttle Stopper Adjusting
Screw
(25) Pilot Jet
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-M16
(2) Carburetor (DF972-E2)
NOTE
• DF Carburetor operates the same as a gasoline
carburetor in gasoline fuel.
With the fuel select switch (8) in the "GASOLINE"
position "D" and the main switch in the "ON" position,
the battery current flows to the gasoline cut off solenoid
(6). Therefore gasoline fuel in the float chamber flows to
the mixing chamber.
When the fuel select switch (8) is turned to the
"LPG" position "E", the battery current stops to the
gasoline cut off solenoid (6) and flows to the LPG cut off
solenoid (3) and LPG shut off solenoid valve (9).
Then, the gasoline fuel flow is shut and LPG fuel
flows to the mixing chamber.
The mixer meters both fuel and air, and procedures
an air / fuel mixture that has the proper ratio as required
by the engine.
When the engine starts, the LPG furl flows out from
main jet (4) to venture a constant amount and is mixed
with air quantity corresponding to the opening of the
throttle valve (1) and is supplied to the cylinder.
When the main switch (7) turned to the "OFF"
position, the battery current stops to the both of
solenoids.
Then, both gasoline fuel and LPG fuel can not flow to
the mixing chamber.
9Y1210318ENM0031US0
(1) Choke Valve
(2) Throttle Valve
(3) LPG Cut Off Solenoid
(4) LPG Main Jet
(5) Gasoline Main Jet
(6) Gasoline Cut Off Solenoid
(7) Main Switch
(8) Fuel Select Switch
(9) LPG Shut Off Solenoid Valve
A : Air
B : LPG Fuel (gaseous)
C : Mixture (Air / Fuel)
D : Gasoline Position
E : LPG Position
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-M17
(3) Gas Mixer (DG972-E2)
The gas mixer is equipment to mix the fuel supplied
from the regulator with air and to send the mixture to the
cylinder.
9Y1210318ENM0032US0
[3] VAPORIZER (DF972-E2)
Vaporizer is a device which converts the liquid fuel
into the gaseous fuel and the following structures and
functions are possessed.
Primary Chamber
The liquid fuel is decompressed (the first
decompression) and it is evaporated.
Secondary Chamber
The fuel which flows in is decompressed from the
primary chamber to the vicinity of the atmospheric
pressure further (the second decompression).
Water Passage
The coolant of the engine is made to circulate as a
heat source to evaporate the LPG.
Vacuum Lock Chamber
When the engine stops, the fuel from primary
chamber is prevented from flowing out.
9Y1210318ENM0033US0
(1) Venturi
(2) Throttle Valve
(A) Air
(B) Natural Gas
(C) Mixture (Air / Natural Gas)
(1) Secondary Chamber
(2) Water Passage
(3) Primary Chamber
(4) Vacuum Lock Chamber
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-M18
Primary Chamber
The liquid fuel which pushes the primary valve (6)
open passes between the valve and the valve seat (7),
enters primary chamber (1), and decompresses and is
evaporated.
When the inflow of the fuel continues and the primary
chamber pressure rises more than the specified
pressure 32.7 kPa (0.3 kgf/cm2, 4.3 psi), the tension in
the diaphragm spring (3) is overcome and do the push
up of primary diaphragm (4).
At this time, do the push up of primary valve lever
spring (2) of primary valve lever (5), primary valve (6) is
shut, and the inflow of the fuel is intercepted.
The tension in the diaphragm spring (3) grows more
than the primary chamber pressure when the fuel is
consumed and the primary chamber pressure lowers
more than a regulated value and a primary diaphragm is
depressed below.
The primary valve lever (5) is depressed at the same
time.
A primary valve opens and the fuel flows in again.
When the diaphragm tears by any chance and the
fuel flows in the primary diaphragm spring side, the
primary diaphragm spring side is connected with second
chamber in the balance passage so that the fuel should
not flow out outside.
9Y1210318ENM0034US0
(1) Primary Chamber
(2) Primary Valve Lever Spring
(3) Primary Diaphragm Spring
(4) Primary Diaphragm
(5) Primary Valve Lever
(6) Primary Valve
(7) Valve Seat
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-M19
Secondary Chamber
The fuel adjusted with primary chamber to the
specified pressure enters secondary chamber (5)
between secondary valve (1) and the valve seat (2) and
is decompressed to the vicinity of the atmospheric
pressure almost.
A secondary valve is assembled to a part of the
secondary valve lever (3) supported to body and is shut
by the tension of the spring of a secondary valve spring
(4).
A secondary diaphragm pin (6) touches the edge
besides this lever (3).
The one side of secondary diaphragm (8) is faced in
secondary chamber and the other side faces
atmosphere chamber (10).
When the engine stops, the atmospheric pressure is
led in secondary chamber and a secondary valve is shut
by the tension of a secondary valve spring.
When the engine rotates, the negative pressure is
generated in the venturi tube of the mixer.
As for this negative pressure, working secondary
diaphragm (8) is pulled to the second chamber side by
the difference pressure with atmosphere chamber by
second chamber.
Do the push up of the secondary valve lever (3) by
this working, secondary valve is opened, and the fuel
flows in.
When pressure in chamber rises by the fuel which
flows in, the diaphragm is pushed to the atmosphere
chamber side and narrows the opening of the valve and
decreases the supply of the fuel.
Secondary chamber is almost maintained in the
atmospheric pressure by the thing to repeat such
working.
9Y1210318ENM0035US0
(1) Secondary Valve
(2) Valve Seat
(3) Secondary Valve Lever
(4) Secondary Valve Lever
Spring
(5) Secondary Chamber
(6) Diaphragm Pin
(7) Balance Spring
(8) Secondary Diaphragm
(9) Balance Lever Spring
(10) Atmosphere Chamber
(11) Idle Adjust Screw
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-M20
Vacuum Lock Chamber
1) Operation when engine stops
Because pressure on the vacuum lock chamber (3)
side and the secondary chamber (4) side is equal,
vacuum lock diaphragm (5) is pushed to the second
chamber side by the tension of vacuum lock diaphragm
spring (2).
Secondary valve and the seat are made to close as
vacuum lock diaphragm pin (6) pushes secondary valve
lever (7) and the fuel leakage is prevented.
2) Operation at engine starting
The negative pressure is caused in inlet manifold at
the same time as the cranking's beginning.
This negative pressure acts in vacuum lock chamber
(3) and vacuum lock diaphragm (5) is drawn to the
vacuum lock chamber side.
As a result, the movement of secondary valve lever
(7) becomes free and the fuel inflow adjustment due to
secondary valve (1) becomes possible.
The negative pressure in inlet manifold always works
while the engine is rotating and the movement of
secondary valve lever is tuned to the movement of
secondary diaphragm.
9Y1210318ENM0036US0
[4] REGULATOR (DG972-E2)
The regulator is equipment that regulates the fuel
pressure supplied to the gas mixer to be constant.
The negative pressure of the suction stroke makes
the inside pressure of the regulator negative.
The negative pressure of the regulator makes the
diaphragm (1) push the lever (6).
Pushing the lever (6) opens the valve (8), with the
screw (7) acting as a fulcrum, which makes the fuel
suctioned.
9Y1210318ENM0037US0
(1) Secondary Valve
(2) Vacuum Lock Diaphragm
Spring
(3) Vacuum Lock Chamber
(4) Secondary Chamber
(5) Vacuum Lock Diaphragm
(6) Diaphragm Pin
(7) Secondary Valve Lever
(1) Diaphragm
(2) Balance Spring
(3) Balance Screw
(4) Tamper Cap
(5) Spring
(6) Lever
(7) Screw
(8) Valve
(A) OUT
(B) IN
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-M21
[5] GOVERNOR
The engine is equipped with a centrifugal ball
mechanical governor which activates the throttle in
response to engine speed.
When the engine is carrying a load and running at
rated speed, the speed will drop if the load is increased
even slightly. In this case, the governor automatically
opens the throttle valve of the carburetor to maintain the
original speed.
Dumping the load suddenly will cause a rapid
increase in speed. In this case, the governor
automatically moves the throttle valve in closing
direction to prevent the engine from increasing its speed.
1) When engine is carrying a load and running at
rated speed
When there is no change in load, the centrifugal
force of the ball (6) which is attached to the governor
gear (4) balances with the tensile force of the governor
spring (8) via governor sleeve (5), fork lever (7),
governor lever shaft (3) and governor lever (2). The
engine speed and output are thus kept constant.
2) When load is applied to engine
When the load is applied to the engine running at
rated speed, the speed of the governor gear (4) which is
connected to the idle gear decreases. As a result, the
centrifugal force of the ball (6) becomes smaller. The
tensile force of the spring (8) overcomes the centrifugal
force, and the governor lever (2) causes the throttle lever
(1) to move in the open direction (B). The original engine
speed is thus maintained.
3) When load is dumped
When the load is dumped suddenly, the centrifugal
force of the ball (6) overcomes the tensile force of the
spring (8). As a result, the governor lever (2) causes the
throttle lever (1) to move in the shut direction (A) and
prevents the engine from increasing its speed.
9Y1210318ENM0038US0
[6] INLET MANIFOLD
Part of coolant heated in the water jacket is
channeled to the inlet manifold, where the hot coolant
heats the fuel-air mixture for better carburation. Heating
effect is particularly good when the engine is running at
low speeds and with light load is cold weather, thus
improving fuel economy and acceleration.
9Y1210318ENM0039US0
(1) Throttle Lever
(2) Governor Lever
(3) Governor Lever Shaft
(4) Governor Gear
(5) Governor Sleeve
(6) Ball
(7) Fork Lever
(8) Governor Spring
(9) Speed Control Lever
(10) WG Carburetor,
DF Carburetor
(11) DG Gas Mixer
A : Shut Direction
B : Open Direction
(1) Intake Manifold
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-M22
[7] FUEL FILTER (FOR GASOLINE LINE)
The fuel filter is installed in the fuel line between the
fuel tank and the feed pump.
As the fuel flows from the inlet (A) through the filter
element (1), the dirt and impurities in the fuel are filtered,
allowing only clean fuel to penetrate the inside of the
filter element. The cleaned fuel flows out from the outlet
(B).
9Y1210318ENM0040US0
[8] ELECTRO MAGNETIC FUEL FEED PUMP (FOR GASOLINE
LINE)
An electro magnetic pump uses a transistor that
causes the pump to start pumping fuel when the engine
is switched on.
Therefore, fuel is supplied to the carburetor
regardless of engine speed. This pump is driven by the
battery. It can therefore be operated even with the
engine being stopped.
9Y1210318ENM0041US0
Type of filter element Accordion-pleated paper type
Material of filter element Cotton fiber
Filter mesh 15 µm (0.00059 in.)
(1) Filter Element A : Inlet
B : Outlet
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-M23
5. IGNITION SYSTEM
[1] DEGITAL IGNITION SYSTEM
General
The function of an ignition system is to provide the
electrical spark that ignites the air/fuel mixture in the
cylinder at precisely the correct time.
For this purpose, the pick-up sensor (6) detects
voltage waveform according to the shape of the rotor (2)
that is built into the flywheel (1). The voltage waveform
signal is fed to the igniter (3), in which the signal is
converted by a microprocessor to the angular and rpm
data that corresponds to each cylinder. Based on this
information, an optimum timing is figured out by the
microprocessor to cut off the current that flows to the
ignition coil (4) of each cylinder. The duration of current
flowing to the ignition coil (4) is also controlled. In this
way, a high voltage is generated at the secondary
winding of the ignition coil (4), which activates the spark
plug (5).
Without any mechanical contact, the ignition system
is digitally microprocessor-controlled for greater
reliability and higher precision.
• Control at ignition time :
The ignition time is controlled according to the
engine speed.
• Control at energizing time :
The energizing time of the ignition coil is controlled
according to the engine speed.
• Lock prevention :
Intercept the current of the coil for the damage
prevention of the coil when the ignition switch is
energized to the coil as turning on.
• Lock prevention :
Intercept the current of the coil for the damage
prevention of the coil when the ignition switch is
energized to the coil as turning on.
9Y1210318ENM0042US0
(1) Flywheel
(2) Rotor
(3) Ignitor
(4) Ignition Coil
(5) Spark Plug
(6) Pick-up Sensor
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-M24
6. ELECTRICAL SYSTEM
[1] STARTING SYSTEM
Starter
The starter is the electromagnetic drive type.
9Y1210318ENM0043US0
Operation of Starter
[When key switch is turned to "START" position]
The contacts of key switch (1) close and the holding
coil (3) is connected to the battery to pull the plunger (5).
The pull-in coil (4) and the starting motor are also
connected to the battery.
The pinion (8) is pushed against the ring gear (9)
with the overrunning clutch (7) by the shift lever (6) and
the magnetic switch is closed.
[When the solenoid switch is closed]
The current from the battery flows through the
solenoid switch (2) to the starting motor.
The pinion (8), which is pushed against the ring gear
(9) and rotated along the spline, meshes with the ring
gear to crank the engine.
The engine starts and increases its speed.
While the pinion spins faster than the armature, the
overrunning clutch (7) allows the pinion to spin
independently from the armature.
The pull-in coil (4) is short-circuited through the
solenoid switch (2) and the key switch (1).
[When the key switch is released]
The current from the battery flows to the holding coil
(3) through the pull-in coil (4) to diminish the magnetism
between them.
The plunger (5) is pushed by the spring to pull in the
pinion.
9Y1210318ENM0044US0
Type of motor DC, Series-wound, Electromagnetic drive
Nominal output 12V
Nominal output 1.0 kW
Nominal output 30 seconds (Do not rotate continuously for longer periods.)
Direction of rotation Clockwise as viewed from pinion side
(1) Solenoid Switch
(2) Plunger
(3) Spring
(4) Shift Lever
(5) Brush
(6) Commutator
(7) Armature
(8) Field Coil
(9) Overrunning Clutch
(1) Key Switch
(2) Solenoid Switch
(3) Holding Coil
(4) Pull-in Coil
(5) Plunger
(6) Shift Lever
(7) Overrunning Clutch
(8) Pinion
(9) Ring Gear
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-M25
Key Switch
The key switch has 4 positions. The terminal "30" is
connected to the battery.
It is released at the "START" position and returns to
the "ON" position.
[START]
When the key is turned to the "START" position,
through the "ON" position the current supplied to the
starter to regulator, oil lamp and accessory.
50 to starter
30 from battery
AC to regulator, oil lamp and accessory
[ON]
Only the terminal "AC" is connected to the battery.
At any position of the key except the "OFF" position, the
terminal "AC" is connected to the "30" terminal.
30 from battery
AC to regulator, oil lamp and accessory
9Y1210318ENM0045US0
[2] CHARGING SYSTEM
Alternator
This alternator is an 8-8 pole rotating magnet type
generator. It is simple in construction, consisting of a
stator and rotor. The rotor is made up of eight permanent
magnet pole pieces assembled on a shaft and rotates on
the center of the stator around which eight
electromagnetic coils are provided for. This alternator
produces higher voltage in slow speed rotation, and
charges electric current to the battery during engine
idling.
9Y1210318ENM0046US0
Regulator
The regulator performs rectification and voltage
regulation. The regulator converts AC into DC which
flows through the power consuming circuits and the
battery, and also charges the battery. If however, the
battery voltage exceeds a certain level. The DC current
is cut off from the charging circuit to prevent
overcharging.
9Y1210318ENM0047US0
Model RS5155
Part No. RP201-53710
Weight Approx. 200 g
Regulated voltage 14 to 15 V
Battery to be used 12 V, 28 AH
Charge indication lamp 12 V, 3.4 W
Alternator to be used
Under 100 V of peak value of no-load
voltage
Under 16 A of output current
(1) Alternator
(2) Blue Lead Wire
(3) Regulator
(4) Yellow Lead Wire
(5) Red Lead Wire
(6) Overrunning Clutch
(7) Black Lead Wire
(8) Charge Lamp
(9) Battery
(10) Load
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-M26
Features
1. This small-sized regulator can control large output
current because charging current is supplied and
stopped by thyristor (series system).
2. Built-in AC diode generation detecting circuit permits
a charge indication lamp (12 V, 3.4 W) to be easily
connected.
3. Protection diode protects regulator when battery is
wrongly connected.
9Y1210318ENM0048US0
Charging Mechanism
The charging mechanism is described in four
sections.
1. When key switch is "ON".
2. At starting
3. In charging
4. Over-charge protection
9Y1210318ENM0049US0
1. When Key Switch is "ON"
When the engine is at standstill with key switch set at
position 1, the circuit functions to light LAMP, as shown
in figure (A). With key switch at position 1, current flows
to base of Q2 through the route of BATT → emitter / base
of Q2 → R1 → D6 → BATT and collector of Q2 is then
turned on. As a result, current also flows to LAMP
through the route of BATT → emitter / collector of Q2 →
D5 → LAMP → BATT lighting LAMP to indicate that
charging is not carried out. At this time, through current
flows to base of Q3 through the route of BATT → emitter
/ base of Q3 → R2 → D6 → BATT, collector of Q3 has
no current because GEN is stationary.
9Y1210318ENM0050US0
(1) Blue Lead Wire
(2) Black Lead Wire
(3) Blue Lead Wire
(4) Green Lead Wire
(5) Yellow Lead Wire
(6) Red Lead Wire
(1) GEN : Magnet type AC generator
(2) Blue : GEN connecting terminal
(3) Red : BATT + connecting terminal
(4) Green : LAMP connecting terminal
(5) LAMP : Charge indication lamp (not included in the basic engine)
(6) Yellow : BATT voltage test terminal
(7) Black : BATT - connecting terminal
(8) KEY SW : Key switch
(9) BATT : Battery (not included in the basic engine)
S1, S2 : Output control / rectification thyristor (SCR)
D1, D2 : Output rectifying diode
D3, D4 : GEN generation detecting diode
D5, D6 : Protection diode for wrong connecting of BATT
Z1 : BATT terminal voltage setting diode
Q1 : GEN generation detecting transistor
Q2 : LAMP on / off transistor
Q3 : Gate current control transistor
Q4 : BATT voltage detecting transistor
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-M27
2. At Starting
When key switch is turned to position 2, coil of starter
relay is energized and starter starts engine. GEN also
starts generation for charging and LAMP is turned off.
In detail, with GEN starting, current flows to base of
Q1 through the route of GEN → D1 → emitter / base of
Q1 → R4 → D4 → GEN, or GEN → D2 → emitter / base
of Q1 → R4 → D3 → GEN, and therefore current also
flows through Q1, shortcircuiting emitter and base of Q2.
As a result, base current of Q2 is interrupted, Q2 is
turned off and accordingly current to LAMP is also
interrupted.
9Y1210318ENM0051US0
3. In Charging
Because BATT terminal voltage just after engine
start is lower than setting value (14 to 15 V), or lower
than zener level of Z1, current is not supplied to base of
Q4 and Q4 is off, as shown in figure (B). Q3 is on with
base current which flows through the route of BATT →
emitter / base of Q3 → R2 → D6 → BATT, and gate
current is supplied to S1 or S2 through the route of GEN
→ D1 → emitter / collector of Q3 → R3 → gate / cathode
of S2 → GEN, or GEN → D2 emitter / collector of Q3 →
R3 → gate / cathode of S1 → GEN.
When engine speed is increased so that GEN
generation voltage becomes higher than BATT terminal
voltage, S1 or S2 is turned on and, as shown in figure
(C), charge current is supplied to BATT through the route
of GEN → D1 → BATT → anode / cathode of S2 → GEN,
or GEN → D2 → BATT → anode / cathode of S1 →
GEN.
After S1 or S2 is turned on, collector current of Q1
and base current of Q3 are supplied by GEN, not BATT.
When key switch is turned to position 1 after engine
is started, BATT is charged, if BATT terminal voltage is
lower than the setting value, or zener level of Z1.
9Y1210318ENM0052US0
4. Over-Charge Protection
When BATT terminal voltage is higher than the
setting value or zener level of Z1, BATT is not charged
by the function of circuit as shown in figure (D). That is,
Q4 is on with base current which flows through the route
of BATT → emitter / base of Q4 → Z1 → D6 → BATT,
shortcircuiting emitter and base of Q3. Therefore, Q3 is
off with no base current and gate current is not supplied
to S1 and S2. Consequently S1 and S2 are off and BATT
is not charged.
9Y1210318ENM0053US0
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-M28
[3] SOLENOID
When the key switch is turned on, a current flows to
the solenoid, which in turn opens the solenoid valve.
When the key switch is turned off, the solenoid valve
closes, blocking the gasoline main jet (2) / LPG main jet
(4).
9Y1210318ENM0054US0
(1) Gasoline Solenoid Valve
(2) Gasoline Main Jet
(3) LPG Solenoid Valve
(4) LPG Main Jet
[A] WG972-E2
[B] DF972-E2
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-M29
7. ELECTRONIC GOVERNOR
Electronic governor combines the electric actuator
with integrated speed control software to control the
speed of the engine. Electronic governor is a
microprocessor-based control that is incorporated into
the actuator, creating a single integrated package. This
eliminates the need for an additional driver box and
speed control box.
9Y1210318ENM0055US0
(1) Actuator
KiSC issued 06, 2009 A
CONTENTS
1. TROUBLESHOOTING.................................................................................................................1-S1
[1] FOR GENERAL.....................................................................................................................1-S1
[2] FOR GASOLINE FUEL .........................................................................................................1-S2
[3] FOR LPG FUEL.....................................................................................................................1-S2
[4] FOR NATURAL GAS FUEL ..................................................................................................1-S3
[5] FOR ELECTRONIC GOVERNOR.........................................................................................1-S4
2. SERVICING SPECIFICATIONS ..................................................................................................1-S7
3. TIGHTENING TORQUES..........................................................................................................1-S13
[1] TIGHTENING TORQUES FOR SPECIAL USE SCREWS, BOLTS AND NUTS.................1-S13
[2] TIGHTENING TORQUES FOR GENERAL USE SCREWS, BOLTS AND NUTS...............1-S14
4. CHECKING, DISASSEMBLING AND SERVICING ...................................................................1-S15
[1] CHECKING AND ADJUSTING............................................................................................1-S15
(1) Engine Body ..................................................................................................................1-S15
(2) Lubricating System........................................................................................................1-S18
(3) Cooling System .............................................................................................................1-S18
(4) Fuel System...................................................................................................................1-S20
(5) Ignition System..............................................................................................................1-S24
(6) Electrical System...........................................................................................................1-S28
(7) Electronic Governor.......................................................................................................1-S30
[2] DISASSEMBLING AND ASSEMBLING ..............................................................................1-S31
(1) Draining Coolant and Engine Oil ...................................................................................1-S31
(2) External Components ....................................................................................................1-S32
(3) Cylinder Head, Valves and Oil Pan ...............................................................................1-S37
(4) Thermostat ....................................................................................................................1-S40
(5) Timing Gear, Camshaft and Fuel Camshaft ..................................................................1-S41
(6) Piston and Connecting Rod...........................................................................................1-S43
(7) Crankshaft .....................................................................................................................1-S45
(8) Starter............................................................................................................................1-S48
(9) Dynamo .........................................................................................................................1-S49
(10)Alternator.......................................................................................................................1-S50
[3] SERVICING.........................................................................................................................1-S51
(1) Cylinder Head and Valves .............................................................................................1-S51
(2) Timing Gear and Camshaft ...........................................................................................1-S56
(3) Piston and Connecting Rod...........................................................................................1-S59
(4) Crankshaft .....................................................................................................................1-S61
(5) Cylinder .........................................................................................................................1-S65
(6) Oil Pump........................................................................................................................1-S66
(7) Starter............................................................................................................................1-S67
(8) Alternator .......................................................................................................................1-S69
SERVICING
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S1
1. TROUBLESHOOTING
[1] FOR GENERAL
Symptom Probable Cause Solution Reference Page
Engine Will Not Turn
Over
Engine jammed Check engine to find
the problem and
repair it

Battery discharged Charge –
Starter malfunctioning Repair or replace 1-S28
Wires disconnected Reconnect –
Engine Turns Over
Slowly but Does Not
Start
Increased resistance of moving parts Repair or replace –
Excessively high viscosity engine oil at low
temperature
Use specified engine
oil
G-8
Engine Turns Over at
Normal Speed but
Does Not Start
Compression leak Check the
compression
pressure and repair
1-S15
Improper valve clearance Adjust 1-S17
Defective ignition coil Replace 1-S26
Defective spark plug Adjust spark plug gap
or replace
G-13
Defective ignitor Replace 1-S27
Clogged air cleaner Clean or replace G-11, G-12
Rough Low-Speed
Running and Idling
Defective ignition coil Replace 1-S26
Defective spark plug Adjust spark plug gap
or replace
G-13
Defective ignitor Replace 1-S27
Incorrect governor adjustment Adjust 1-S20
Improper valve clearance Adjust 1-S17
Rough High-Speed
Running
Defective ignitor Replace 1-S27
Defective spark plug Adjust spark plug gap
or replace
G-13
Defective ignition coil Replace 1-S26
Incorrect governor adjustment Adjust 1-S20
Engine Speed Does
Not Increase
Incorrect governor adjustment Adjust 1-S20
Defective ignitor Replace 1-S27
Clogged air cleaner Clean or replace G-11, G-12
Deficient Output Improper intake or exhaust valve sealing Replace 1-S53,
1-S54
Incorrect governor adjustment Adjust 1-S20
Excessive carbon in engine Remove carbon –
Improper valve clearance Adjust 1-S17
Piston ring and cylinder worn Replace 1-S60,
1-S65
Clogged air cleaner Clean or replace G-11, G-12
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S2
9Y1210318ENS0001US0
[2] FOR GASOLINE FUEL
9Y1210318ENS0002US0
[3] FOR LPG FUEL
9Y1210318ENS0003US0
Engine Noise Improper valve clearance Adjust 1-S17
Spark knock due to low-octane fuel or carbon Use higher-octane
fuel and remove
carbon

Rattles from loosely mounted external
components
Retighten –
Symptom Probable Cause Solution Reference Page
Symptom Probable Cause Solution Reference Page
Engine Turns Over at
Normal Speed but
Does Not Start
No fuel Replenish fuel –
Defective fuel system Check fuel line and
carburetor and repair

Over choked Clean spark plug –
Flooding from carburetor Check carburetor and
repair / replace

Rough Low-Speed
Running and Idling
Incorrect carburetor idle adjustment Adjust 1-S21
Engine Speed Does
Not Increase
Incorrect carburetor adjustment Adjust 1-S21
Symptom Probable Cause Solution Reference Page
Engine Turns Over at
Normal Speed but
Does Not Start
No LPG fuel Replenish LPG fuel
Check LPG tank
valve
Check shut off
solenoid valve

Defective vacuum lock system Check vacuum hose
Replace vaporizer
1-S24
Defective throttle lever position Set throttle lever to
the low idle position
1-S21
Rough Low-Speed
Running and Idling
Shortage of gas supply Replenish LPG fuel
Check shut off
solenoid valve

Defective idling Replace vaporizer
Draining tar from
vaporizer
G-19, G-22
Defection Output LPG density is rich Replace vaporizer –
Shortage LPG Repair or replace of
fuel system
Replace vaporizer

KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S3
[4] FOR NATURAL GAS FUEL
9Y1210318ENS0004US0
Symptom Probable Cause Solution Reference Page
Engine Turns Over at
Normal Speed but
Does Not Start
No fuel Check gas source
Check shut off
solenoid valve

Defective fuel system Check fuel system
and repair

Rough Low-Speed
Running and Idling
Shortage of gas supply Check gas source
Check shut off
solenoid valve

Defective idling Replace regulator
Draining tar from
regulator

Defection Output Gas density is rich Replace regulator –
Shortage gas Repair or replace of
fuel system
Replace regulator

KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S4
[5] FOR ELECTRONIC GOVERNOR
NOTE
• This troubleshooting describe the procedure which does not use the service tool (soft wear).
Engine does not start : Step 1
9Y1210318ENS0005US0
(1) Refer to [Adjust Governor Lever of Electronic Governor]
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S5
Engine does not start : Step 2
9Y1210318ENS0006US0
(1) Refer to the [Air Gap of Engine Speed Sensor for Electronic Governor]
(2) Refer to the [Resistance of Engine Speed Sensor for Electronic Governor]
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S6
Engine unstable
9Y1210318ENS0007US0
(1) Refer to the [Adjust Governor Lever of Electronic Governor]
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S7
2. SERVICING SPECIFICATIONS
ENGINE BODY
Item Factory Specification Allowable Limit
Valve Clearance (Cold) 0.145 to 0.185 mm
0.00571 to 0.00728 in.

Compression Pressure –
Variance Among
Cylinder
1.27 MPa
13.0 kgf/cm2
185 psi

0.88 MPa
9.0 kgf/cm2
130 psi
10 % or less
Top Clearance 1.35 to 1.65 mm
0.0532 to 0.0649 in.

Cylinder Head Surface Flatness – 0.05 mm
0.002 in.
Valve Recessing (Intake and Exhaust) −0.10 to 0.10 mm
−0.0039 to 0.0039 in.
0.30 mm
0.012 in.
Valve Stem to Valve Guide
• Valve Stem
• Valve Guide
Clearance
O.D.
I.D.
0.030 to 0.057 mm
0.0012 to 0.0022 in.
5.968 to 5.980 mm
0.2350 to 0.2354 in.
6.010 to 6.025 mm
0.2367 to 0.2372 in.
0.10 mm
0.0039 in.


Valve Face Angle 0.79 rad
45 °

Valve Seat Angle 0.79 rad
45 °

Width 2.12 mm
0.0835 in.

Valve Timing (Intake Valve) Open
Close
0.35 rad
20 °
before T.D.C.
0.79 rad
45 °
after B.D.C.


Valve Timing (Exhaust Valve) Open
Close
0.87 rad
50 °
before B.D.C.
0.26 rad
15 °
after T.D.C.


Valve Spring Free Length
Tilt
Setting Load /
Setting Length
31.3 to 31.8 mm
1.24 to 1.25 in.

65 N / 27.0 mm
6.6 kgf / 27.0 mm
15 lbf / 1.06 in.
28.4 mm
1.12 in.
1.0 mm
0.039 in.
55 N / 27.0 mm
5.6 kgf / 27.0 mm
12 lbf / 1.06 in.
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S8
Rocker Arm Shaft to Rocker Arm
• Rocker Arm Shaft
• Rocker Arm
Oil Clearance
O.D.
I.D.
0.016 to 0.045 mm
0.00063 to 0.0017 in.
10.473 to 10.484 mm
0.41233 to 0.41275 in.
10.500 to 10.518 mm
0.41339 to 0.41409 in.
0.15 mm
0.0059 in.


Push Rod Alignment – 0.25 mm
0.0098 in.
Tappet to Tappet Guide Bore
• Tappet
• Tappet Guide Bore
Oil Clearance
O.D.
I.D.
0.016 to 0.052 mm
0.00063 to 0.0020 in.
17.966 to 17.984 mm
0.70733 to 0.70803 in.
18.000 to 18.018 mm
0.70867 to 0.70937 in.
0.10 mm
0.0039 in.


Timing Gear
• Crank Gear to Idle Gear
• Idle Gear to Cam Gear
• Idle Gear to Injection Pump Gear
• Crank Gear to Oil Pump Drive Gear
Backlash
Backlash
Backlash
Backlash
0.0430 to 0.124 mm
0.00170 to 0.00488 in.
0.0470 to 0.123 mm
0.00185 to 0.00484 in.
0.0410 to 0.124 mm
0.00162 to 0.00488 in.
0.0410 to 0.123 mm
0.00162 to 0.00484 in.
0.15 mm
0.0059 in.
0.15 mm
0.0059 in.
0.15 mm
0.0059 in.
0.15 mm
0.0059 in.
Idle Gear Side Clearance 0.20 to 0.51 mm
0.0079 to 0.020 in.
0.80 mm
0.031 in.
Camshaft Side Clearance
Alignment
Cam Height (Intake
and Exhaust)
0.15 to 0.31 mm
0.0059 to 0.012 in.

26.88 mm
1.058 in.
0.50 mm
0.020 in.
0.01 mm
0.0004 in.
26.83 mm
1.056 in.
Camshaft Journal to Cylinder Block Bore
• Camshaft Journal
• Cylinder Block Bore
Oil Clearance
O.D.
I.D.
0.050 to 0.091 mm
0.0020 to 0.0035 in.
32.934 to 32.950 mm
1.2967 to 1.2972 in.
33.000 to 33.025 mm
1.2993 to 1.3001 in.
0.15 mm
0.0059 in.


Idle Gear Shaft to Idle Gear Bushing
• Idle Gear Shaft
• Idle Gear Bushing
Oil Clearance
O.D.
I.D.
0.020 to 0.084 mm
0.00079 to 0.0033 in.
19.967 to 19.980 mm
0.78611 to 0.78661 in.
20.000 to 20.051 mm
0.78741 to 0.78940 in.
0.10 mm
0.0039 in.


Item Factory Specification Allowable Limit
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S9
Piston Pin Bore I.D. 20.000 to 20.013 mm
0.78741 to 0.78791 in.
20.05 mm
0.7894 in.
Piston Pin to Small End Bushing
• Piston Pin
• Small End Bushing
Oil Clearance
O.D.
I.D.
0.012 to 0.038 mm
0.00048 to 0.0014 in.
20.002 to 20.013 mm
0.78748 to 0.78791 in.
20.025 to 20.040 mm
0.78839 to 0.78897 in.
0.10 mm
0.0039 in.


Piston Pin to Small End Bushing
(Spare Parts)
• Small End Bushing
Oil Clearance
I.D.
0.013 to 0.075 mm
0.00052 to 0.0029 in.
20.026 to 20.077 mm
0.78843 to 0.79043 in.
0.15 mm
0.0059 in.

Piston Ring Gap Top Ring
Second Ring
Oil Ring
(Upper and lower
rail)
0.15 to 0.35 mm
0.0059 to 0.013 in.
0.30 to 0.45 mm
0.012 to 0.017 in.
0.20 to 0.70 mm
0.0079 to 0.027 in.
1.25 mm
0.0492 in.
1.25 mm
0.0492 in.
1.25 mm
0.0492 in.
Piston Ring to Piston Ring Groove Top Ring
(Clearance)
Second Ring
(Clearance)
Oil Ring
(Clearance)
0.080 to 0.12 mm
0.0032 to 0.0047 in.
0.065 to 0.10 mm
0.0026 to 0.0039 in.
0.060 to 0.15 mm
0.0024 to 0.0059 in.
0.15 mm
0.0059 in.
0.15 mm
0.0059 in.
0.20 mm
0.0079 in.
Connecting Rod Alignment – 0.05 mm
0.002 in.
Crankshaft Side Clearance
Alignment
0.15 to 0.31 mm
0.0059 to 0.012 in.

0.50 mm
0.020 in.
0.02 mm
0.0008 in.
Crankpin to Crankpin Bearing
• Crankpin
• Crankpin Bearing
Oil Clearance
O.D.
I.D.
0.020 to 0.051 mm
0.00079 to 0.0020 in.
33.959 to 33.975 mm
1.3370 to 1.3375 in.
33.995 to 34.010 mm
1.3384 to 1.3389 in.
0.15 mm
0.0059 in.


Crankshaft Journal to Crankshaft Bearing 1
• Crankshaft Journal
• Crankshaft Bearing 1
Oil Clearance
O.D.
I.D.
0.0340 to 0.106 mm
0.00134 to 0.00417 in.
43.934 to 43.950 mm
1.7297 to 1.7303 in.
43.984 to 44.040 mm
1.7317 to 1.7338 in.
0.20 mm
0.0079 in.


Item Factory Specification Allowable Limit
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S10
Crankshaft Journal to Crankshaft Bearing 2
(Flywheel Side)
• Crankshaft Journal
• Crankshaft Bearing 2
Oil Clearance
O.D.
I.D.
0.028 to 0.059 mm
0.0011 to 0.0023 in.
43.934 to 43.950 mm
1.7297 to 1.7303 in.
43.978 to 43.993 mm
1.7315 to 1.7320 in.
0.20 mm
0.0079 in.


Crankshaft Journal to Crankshaft Bearing 3
(Intermediate)
• Crankshaft Journal
• Crankshaft Bearing 3
Oil Clearance
O.D.
I.D.
0.028 to 0.059 mm
0.0011 to 0.0023 in.
43.934 to 43.950 mm
1.7297 to 1.7303 in.
43.978 to 43.993 mm
1.7315 to 1.7320 in.
0.20 mm
0.0079 in.


Cylinder Liner
[Standard]
I.D. 74.500 to 74.519 mm
2.9331 to 2.9338 in.
74.669 mm
2.9397 in.
Cylinder Liner
[Oversize : 0.5 mm (0.02 in.)]
I.D. 75.000 to 75.019 mm
2.9528 to 2.9535 in.
75.150 mm
2.9587 in.
Item Factory Specification Allowable Limit
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S11
LUBRICATING SYSTEM
COOLING SYSTEM
IGNITION SYSTEM
Item Factory Specification Allowable Limit
Engine Oil Pressure At Idle Speed
At Rated Speed
More than 50 kPa
0.5 kgf/cm2
7 psi
200 to 440 kPa
2.0 to 4.5 kgf/cm2
29 to 64 psi

150 kPa
1.5 kgf/cm2
21 psi
Inner Rotor to Outer Rotor Clearance 0.030 to 0.14 mm
0.0012 to 0.0055 in.

Outer Rotor to Pump Body Clearance 0.070 to 0.15 mm
0.0028 to 0.0059 in.

Inner Rotor to Cover Clearance 0.0750 to 0.135 mm
0.00296 to 0.00531 in.

Item Factory Specification Allowable Limit
Fan Belt Tension 7.0 to 9.0 mm / 98 N
0.28 to 0.35 in. / 98 N
(10 kgf, 22 lbf)

Thermostat Valve Opening
Temperature
(At Beginning)
Valve Opening
Temperature
(Opened
Completely)
69.5 to 72.5 °C
157.1 to 162.5 °F
85 °C
185 °F


Radiator Cap Pressure Falling
Time
More than 10 seconds
for pressure fall from
90 → 60 kPa
0.9 → 0.6 kgf/cm2
10 → 9 psi

Radiator Weak Leakage
Test Pressure
No leak at specified
pressure

Item Factory Specification Allowable Limit
Spark Plug (NGK : BKR4E) Plug Gap 0.60 to 0.70 mm
0.024 to 0.027 in.

Resistance of Ignition Coil Primary (+) - (−)
Secondary Side
(Primary (+) - Plug
Cap)
1.87 to 2.53 Ω at 20 °C
10.4 to 15.6 kΩ at 20 °C


Pick-up Sensor Resistance 1.85 to 2.45 kΩ at 20 °C –
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S12
ELECTRICAL SYSTEM
ELECTRONIC GOVERNOR
9Y1210318ENS0008US0
Item Factory Specification Allowable Limit
Starter Commutator
(O.D.)
Difference
(O.D.)
Mica
(Undercut)
Brush
(Length)
28.0 mm
1.10 in.
Less than 0.05 mm
0.002 in.
0.45 to 0.75 mm
0.018 to 0.029 in.
14.0 mm
0.551 in.
27.0 mm
1.06 in.
0.4 mm
0.02 in.
0.2 mm
0.008 in.
11.1 mm
0.437 in.
Alternator No-load Voltage
Stator
(Resistance)
Rotor
(Resistance)
Slip Ring
(O.D.)
Brush
(Length)
More than 13.5 V
Less than 1.0 Ω
2.9 Ω
14.4 mm
0.567 in.
10.5 mm
0.413 in.



14.0 mm
0.551 in.
8.4 mm
0.33 in.
Regulator Regulating Voltage 14.2 to 14.8 V –
Fuel Cut Off Solenoid For Gasoline
(Resistance)
For LPG
(Resistance)
38 Ω at 20 °C
28 Ω at 20 °C


Item Factory Specification Allowable Limit
Engine Speed Sensor to Ring Gear
(for Kubota original parts)
Air Gap
Resistance
0.80 to 1.2 mm
0.031 to 0.047 in.
Approx. 2.15 kΩ


KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S13
3. TIGHTENING TORQUES
Screws, bolts and nuts must be tightened to the specified torque using a torque wrench, several screws, bolts and
nuts such as those used on the cylinder head must be tightened in proper sequence and the proper torque.
9Y1210318ENS0009US0
[1] TIGHTENING TORQUES FOR SPECIAL USE SCREWS, BOLTS
AND NUTS
NOTE
• For "*" marked screws, bolts and nuts on the table, apply engine oil to their threads and seats before
tightening.
• The letter "M" in Size x Pitch means that the screw, bolt or nut dimension stands for metric. The size is
the nominal outside diameter in mm of the threads. The pitch is the nominal distance in mm between two
threads.
9Y1210318ENS0010US0
Item Dimension × Pitch N·m kgf·m lbf·ft
*Cylinder head cover screw M6 x 1.0 9.81 to 11.2 1.00 to 1.15 7.24 to 8.31
*Rocker arm bracket screw M6 x 1.0 12 to 14 1.2 to 1.5 8.7 to 10
*Cylinder head screw M8 x 1.25 40 to 44 4.0 to 4.5 29 to 32
*Fan drive pulley screw M12 x 1.5 118 to 127 12.0 to 13.0 86.8 to 94.0
*Idle gear shaft mounting screw M6 x 1.0 9.81 to 11.2 1.00 to 1.15 7.24 to 8.31
*Connecting rod screw M7 x 0.75 27 to 30 2.7 to 3.1 20 to 22
*Flywheel screw M10 x 1.25 54 to 58 5.5 to 6.0 40 to 43
Bearing case cover mounting screw M6 x 1.0 9.81 to 11.2 1.00 to 1.15 7.24 to 8.31
*Main bearing case screw 2 M7 x 1.0 27 to 30 2.7 to 3.1 20 to 22
*Main bearing case screw 1 M6 x 1.0 13 to 15 1.3 to 1.6 9.4 to 11
Oil pressure switch PT 1/8 15 to 19 1.5 to 2.0 11 to 14
Spark plug M14 x 1.25 20 to 24 2.0 to 2.5 15 to 18
Drain plug M12 x 1.25 33 to 37 3.3 to 3.8 24 to 27
Carburetor mounting nut M8 x 1.25 24 to 27 2.4 to 2.8 18 to 20
Gas mixer mounting nut M8 x 1.25 24 to 27 2.4 to 2.8 18 to 20
Joint for LPG hose of vaporizer
(local arrangement) PT - 1/4 20 to 23 2.0 to 4.0 15 to 17
Joint for vapor hose of vaporizer PT - 3/8 30 to 58 3.0 to 6.0 22 to 43
Joint for coolant hose of vaporizer PT - 3/8 30 to 58 3.0 to 6.0 22 to 43
Actuator mounting screw M5 x 0.8 4.5 to 5.3 0.45 to 0.55 3.3 to 3.9
Actuator flange screw M6 x 1.0 9.81 to 11.2 1.00 to 1.15 7.24 to 8.31
Governor lever nut M6 x 1.0 9.81 to 11.2 1.00 to 1.15 7.24 to 8.31
Starter's terminal B mounting nut – 5.9 to 11 0.60 to 1.2 4.4 to 8.6
Dynamo's pulley nut – 40 to 44 4.0 to 4.5 29 to 32
Alternator's pulley nut – 58.4 to 78.9 5.95 to 8.05 43.1 to 58.2
Gasoline solenoid – 7.9 to 11 0.80 to 1.2 5.8 to 8.6
Main jet – 0.98 to 2.8 0.10 to 0.29 0.73 to 2.0
Pilot jet – 0.98 to 3.9 0.10 to 0.40 0.73 to 2.8
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S14
[2] TIGHTENING TORQUES FOR GENERAL USE SCREWS, BOLTS
AND NUTS
If the tightening torque is not specified, refer to the table below for the none specified torques values.
M00000003ENS0013US1
Indication on
top of bolt No-grade or 4T 7T
Indication on
top of nut No-grade or 4T
Unit N·m kgf·m lbf·ft N·m kgf·m lbf·ft
M6 7.9 to 9.3 0.80 to 0.95 5.8 to 6.8 9.81 to 11.2 1.00 to 1.15 7.24 to 8.31
M8 18 to 20 1.8 to 2.1 13 to 15 24 to 27 2.4 to 2.8 18 to 20
M10 40 to 45 4.0 to 4.6 29 to 33 49 to 55 5.0 to 5.7 37 to 41
M12 63 to 72 6.4 to 7.4 47 to 53 78 to 90 7.9 to 9.2 58 to 66
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S15
4. CHECKING, DISASSEMBLING AND SERVICING
[1] CHECKING AND ADJUSTING
(1) Engine Body
Compression Pressure
1. Run the engine until it is warmed up.
2. Stop the engine.
3. Remove the air cleaner, the muffler and all spark plugs.
4. Set a compression tester with the adaptor to the spark plug
hole.
5. Run the engine with the starter for 5 to 10 seconds keeping
throttle valve fully open and read the maximum compression
pressure.
6. Repeat steps 4 and 5 for each cylinder.
7. If the measurement is below the allowable limit, apply a small
amount of oil to the cylinder wall through the spark plug hole and
measure the compression pressure again.
8. If the compression pressure is still less than the allowable limit,
check the top clearance, valve clearance and cylinder head.
9. If the compression pressure increases after applying oil, check
the cylinder wall and piston rings.
NOTE
• Check the compression pressure with the specified valve
clearance.
• Always use a fully charged battery for performing this test.
• Variances in cylinder compression values should be under
10 %.
9Y1210318ENS0013US0
Compression pressure
Factory spec.
1.27 MPa
13.0 kgf/cm2
185 psi
Allowable limit
0.88 MPa
9.0 kgf/cm2
130 psi
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S16
Top Clearance
1. Remove the cylinder head. (Do not attempt to remove the
cylinder head gasket.)
2. Move the piston up and stick a strip of fuse [1.5 mm dia. (0.059
in. dia.), 5.0 to 7.0 mm long (0.20 to 0.27 in. long)] on the piston
head at three positions with grease so as to avoid the intake and
exhaust valves and the combustion chamber ports.
3. Lower the piston, and install the cylinder head and tighten the
cylinder head screws to the specified torque.
4. Turn the flywheel until the piston exceeds top dead center.
5. Remove the cylinder head, and measure the thickness of the
squeezed fuses.
6. If the measurement is not within the factory specifications,
check the oil clearance between the crankpin and crankpin
bearing and between the piston pin and small end bushing.
NOTE
• After checking the top clearance, be sure to assemble the
cylinder head with a new cylinder head gasket.
9Y1210318ENS0014US0
Top clearance Factory spec. 1.35 to 1.65 mm0.0532 to 0.0649 in.
Tightening torque Cylinder head screws
40 to 44 N·m
4.0 to 4.5 kgf·m
29 to 32 lbf·ft
(1) Fuse
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S17
Adjusting the Valve Clearance
IMPORTANT
• The valve clearance must be checked and adjusted when
engine is cold.
1. Remove the cylinder head cover and the spark plugs.
2. Align the "1TC" mark (1) on the flywheel and alignment mark (2)
on the rear end plate so that the No. 1 piston comes to the
compression top dead center.
3. Check the following valve clearance marked with " " using a
feeler gauge.
4. If the clearance is not within the factory specifications, adjust
with the adjusting screw.
5. Then turn the flywheel 6.28 rad (360 °), and align the "1TC"
mark (1) on the flywheel and alignment mark (2) on the rear end
plate so that the No. 1 piston comes to the overlap position.
6. Check the following valve clearance marked with " " using a
feeler gauge.
7. If the clearance is not within the factory specifications, adjust
with the adjusting screw.
: When No. 1 piston is at the compression top dead center position.
: When No. 1 piston is at the overlap position.
NOTE
• The sequence of cylinder numbers is given as No. 1, No. 2
and No. 3 starting from the gear case side.
• After adjusting the valve clearance, secure the adjusting
screw with the lock nut.
9Y1210318ENS0015US0
Adjustable Cylinder Location
of Piston
Valve Arrangement
Intake valve Exhaust valve
No. 1
No. 2
No. 3
Intake and exhaust valve
clearance (cold) Factory spec.
0.145 to 0.185 mm
0.00571 to 0.00728 in.
(1) "1TC" Mark
(2) Alignment Mark
A : Gear Case Side
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S18
(2) Lubricating System
Engine Oil Pressure
1. Remove the engine oil pressure switch, and set an oil pressure
tester.
2. Start the engine. After warming up, measure the oil pressure of
both idling and rated speeds.
3. If the oil pressure is less than the allowable limit, check the
following.
• Engine oil insufficient
• Oil pump defective
• Oil strainer clogged
• Oil filter cartridge clogged
• Oil gallery clogged
• Excessive oil clearance
• Foreign matter in the relief valve
(When reassembling)
• After checking the engine oil pressure, tighten the engine oil
pressure switch to the specified torque.
9Y1210318ENS0016US0
(3) Cooling System
Fan Belt Tension
1. Measure the deflection (A), depressing the belt halfway
between the fan drive pulley and alternator pulley at specified
force 98 N (10 kgf, 22 lbf).
2. If the measurement is not within the factory specifications,
loosen the alternator mounting screws and relocate the
alternator to adjust.
9Y1210318GEG0001US0
Engine oil pressure
At idle
speed
Factory
spec.
More than
50 kPa
0.5 kgf/cm2
7 psi
At rated
speed
Factory
spec.
200 to 440 kPa
2.0 to 4.5 kgf/cm2
29 to 64 psi
Allowable
limit
150 kPa
1.5 kgf/cm2
21 psi
Tightening torque Oil pressure switch
15 to 19 N·m
1.5 to 2.0 kgf·m
11 to 14 lbf·ft
Deflection (A) Factory spec. 7.0 to 9.0 mm0.28 to 0.35 in.
(A) Deflection
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S19
Fan Belt Damage and Wear
1. Check the fan belt for damage.
2. If the fan belt is damaged, replace it.
3. Check if the fan belt is worn and sunk in the pulley groove.
4. If the fan belt is nearly worn out and deeply sunk in the pulley
groove, replace it.
9Y1210318GEG0002US0
Thermostat Valve Opening Temperature
1. Suspend the thermostat in the water by a string with its end
inserted between the valve and seat.
2. Heating the water gradually, read the temperature when the
valve opens and leaves the string.
3. Continue heating and read the temperature when the valve
opens approx. 8 mm (0.3 in.).
4. If the measurement is not within the factory specifications,
replace the thermostat.
9Y1210318ENS0017US0
CAUTION
• When removing the radiator cap, wait at least ten minutes after the engine has stopped and cooled down.
Otherwise, hot water may gush out, scalding nearby people.
9Y1210318ENS0018US0
Radiator Cap Air Leakage
1. Set a radiator tester (1) and an adaptor (2) on the radiator cap.
2. Apply the specified pressure (90 kPa, 0.9 kgf/cm2, 10 psi), and
measure the time for the pressure to fall to 60 kPa (0.6 kgf/cm2,
9 psi).
3. If the measurement is less than the factory specification,
replace the radiator cap.
9Y1210318ENS0019US0
(A) Good (B) Bad
Thermostat's valve
opening temperature Factory spec.
69.5 to 72.5 °C
157.1 to 162.5 °F
Temperature at which
thermostat completely
opens
Factory spec. 85 °C185 °F
Pressure falling time Factory spec.
More than 10 seconds
for pressure fall from
90 to 60 kPa
from 0.9 to 0.6 kgf/cm2
from 10 to 9 psi
(1) Radiator Tester (2) Adaptor
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S20
Radiator Water Leakage
1. Pour a specified amount of water into the radiator.
2. Set a radiator tester (1) and an adaptor (2) and raise the water
pressure to the specified pressure.
3. Check the radiator for water leaks.
4. For water leak from the pinhole, repair with the radiator cement.
When water leak is excessive, replace the radiator.
9Y1210318ENS0020US0
(4) Fuel System
Adjusting Governor
1. Loosen the governor lever nut (3).
2. Set the throttle valve to the fully "OPEN" position with the
governor lever (2), turn the groove on the governor lever shaft
(1) fully clockwise with a screwdriver (to open the governor
completely), and then tighten the nut (3) in this position.
NOTE
• Insert the governor lever to the position 2 mm (0.08 in.) (B)
away from the fork lever shaft end.
9Y1210318ENS0021US0
Radiator water leakage
test pressure Factory spec.
No leak at specified
pressure
(1) Radiator Tester (2) Adaptor
Tightening torque Governor lever nut
9.81 to 11.2 N·m
1.00 to 1.15 kgf·m
7.24 to 8.31 lbf·ft
(1) Governor Lever Shaft
(2) Governor Lever
(3) Governor Lever Nut
A : Open Direction
B : 2 mm (0.08 in.)
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S21
Adjusting Engine Speed
1. Warm up the engine at a medium speed for 10 to 15 minutes.
2. Engine speed is adjusted to approx. 1500 min-1 (rpm) by the
speed control lever (5).
3. Throttle valve (1) is closed by hand and engine speed is
adjusted with the throttle adjust screw (2) to 1200 min-1 (rpm)
(1100 to 1300 min-1 (rpm)).
4. Adjust the low-idling speed adjust screw (3) until the engine
speed reaches 1500 min-1 (rpm) (1400 to 1600 min-1 (rpm)) with
the speed control lever (5) in the minimum speed position.
5. Adjust the high-idling speed adjust screw (4) until the engine
speed reaches 3850 min-1 (rpm) (3850 to 3950 min-1 (rpm)) with
the speed control lever (5) in the maximum speed position.
9Y1210318ENS0022US0
Carburetor (WG972-E2) / Dual Fuel Carburetor (DF972-E2)
The carburetor is tamper resistant; the idle mixture screw has
been covered by tamper plug after adjustment at the factory.
9Y1210318ENS0023US0
Lo-idling speed Factory spec. 1500 min
-1 (rpm)
(1400 to 1600 min-1 (rpm))
Hi-idling speed Factory spec. 3850 min
-1 (rpm)
(3850 to 3950 min-1 (rpm))
(1) Throttle Valve
(2) Throttle Adjust Screw
(3) Low-idling Adjust Screw
(4) High-idling Adjust Screw
(5) Speed Control Lever
(1) Tamper Resistance
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S22
Replacement of Altitude Compensation Kit (Main Jet and Pilot
Jet) (WG972-E2, DF972-E2)
1. Remove the carburetor.
2. Loosen the drain screw (6) to let fuel out.
3. Remove the gasoline solenoid (3).
4. Remove the main jet (4).
5. Install the high-altitude kit's main jet onto the carburetor.
6. Tighten the throttle adjust screw (5) and remove the pilot screw
(1).
7. Replace the existing pilot jet (2) with the high-altitude kit's pilot
jet.
8. Install the gasoline solenoid (3).
9. Install the carburetor in place.
10. Readjust the governor.
11. Adjust the engine speed.
NOTE
• After install the carburetor, the adjustment of governor and
engine speed are executed.
• Prepare a screwdriver that fits the main jet / pilot jet screws
in order not to damage the main jet and pilot jet.
• Replace the air cleaner packing and the carburetor packing
with new ones.
• Make sure there is no leak at the air cleaner packing and the
carburetor packing.
IMPORTANT
• Keep the carburetor inner parts which is removed from
standard carburetor.
9Y1210318ENS0024US0
LPG Vaporizer Regulator (DF972-E2)
LPG vaporizer regulator is tamper resistant; the main and idle
pressure adjustment screws have been covered by tamper caps
after adjustment at the factory.
9Y1210318ENS0025US0
Tightening torque
Carburetor mounting nut
24 to 27 N·m
2.4 to 2.8 kgf·m
18 to 20 lbf·ft
Gasoline solenoid
7.9 to 11 N·m
0.80 to 1.2 kgf·m
5.8 to 8.6 lbf·ft
Main jet
0.98 to 2.8 N·m
0.10 to 0.29 kgf·m
0.73 to 2.0 lbf·ft
Pilot jet
0.98 to 3.9 N·m
0.10 to 0.40 kgf·m
0.73 to 2.8 lbf·ft
(1) Pilot Screw
(2) Pilot Jet
(3) Gasoline Solenoid
(4) Main Jet
(5) Throttle Adjust Screw
(6) Drain Screw
(1) Tamper Resistance
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S23
Natural Gas Regulator (DG972-E2)
Natural gas regulator is tamper resistant; the pressure
adjustment screw have been covered by tamper caps after
adjustment at the factory.
9Y1210318ENS0026US0
Vaporizer Joints (DF972-E2)
1. The direction of the joint for vapor hose is decided upon and a
mark (2) is made.
2. The direction of the joint for coolant hose is decided upon and a
mark is made.
NOTE
• Vaporizer must be installed in an upright position (coolant
hoses at bottom).
• The joints (fitting) can be adjusted to any position. The joint
must be tight in that position.
• Apply an approved for GAS or LPG use liquid gasket (Three
Bond 1104 or its equivalent) to thread (see figure) and
tighten it.
• Drain plug (1) must not be obstructed ; so that it can be
removed during maintenance.
• Apply liquid gasket to the thread of each joint and tighten
them.
• After selecting the joint (fitting) positions, insure that there
are no leaks.
9Y1210318ENS0027US0
(1) Tamper Resistance
Tightening torque
Joint for LPG hose
of vaporizer
(local arrangement)
20 to 23 N·m
2.0 to 4.0 kgf·m
15 to 17 lbf·ft
Joint for vapor hose
of vaporizer
30 to 58 N·m
3.0 to 6.0 kgf·m
22 to 43 lbf·ft
Joint for coolant hose
of vaporizer
30 to 58 N·m
3.0 to 6.0 kgf·m
22 to 43 lbf·ft
(1) Drain Plug
(2) Mark
(3) Liquid Gasket
(4) Thread of Joint
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S24
Vaporizer Piping (DF972-E2)
1. Connect the coolant hose (1) and (2) through the vaporizer.
2. The joint part of vaporizer is adjusted to the upper side (A) and
coolant is replenished through radiator, to bleed air in the
vaporizer.
3. Vaporizer (3) is returned to former position.
4. Connect the vapor hose.
5. Connect the vacuum lock hose (4).
6. Tighten the vaporizer (3).
7. Connect the LPG hose.
• O.D. of joint for vapor hose: 12.7 mm (0.500 in.)
• O.D. of joint for coolant hose: 9.0 mm (0.35 in.)
CAUTION
• All fuel connections added to this engine must be installed
by qualified personnel and utilizing recognized procedures
and standards.
• These non-KUBOTA installed parts, such as hoses,
fittings, piping, should be approved for LPG use and
conform to UL, CSA, NFPA, and all other recognized
standards.
• An approved, listed fuel filter and electromechanical
positive shutoff must be installed between the LPG tank
and KUBOTA vaporizer.
NOTE
• The LPG liquid in joint (fitting) to the vaporizer / regulator is
not provided in the KIT by KUBOTA, due to the many
different connection requirements by the OEM.
The female thread into the vaporizer / regulator is a PT 1/4
METRIC thread. To insure good sealing the correct fitting
must by used.
• Vapor hose between the vaporizer and mixer must be of
280 to 320 mm (11.1 to 12.5 in.) in length, to assure correct
emissions and proper operation.
• Perform air bleeding of the vaporizer (water passage).
• Each hose must be tightened with a hose clamp.
9Y1210318ENS0028US0
(5) Ignition System
Timing Light Test
1. Set the timing light to High-tension cord.
2. Close the fuel cocks.
3. Cranking the engine.
4. If the timing light blinks, the spark plug and ignition coil are
normal.
5. If the timing light does not blink, check the spark plug / ignition
coil.
9Y1210318ENS0029US0
(1) Coolant Hose
(2) Coolant Hose
(3) Vaporizer
(4) Vacuum Lock Hose
A : Joint
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S25
Ignition Timing
1. Using a timing light, check that the ignition timing (stamps on the
flywheel) (4) is aligned with the mark (3) on the rear end plate
(2).
2. The pick-up sensor is tamper resistant (5); the ignition timing
adjustment screw has been covered after adjustment at the
factory.
9Y1210318ENS0030US0
Resistance of Pick-Up Sensor
1. Disconnect the connector.
2. Measure the resistance with an ohmmeter.
3. If the resistance is not with in the factory specifications, replace
it.
NOTE
• This check sheet shows the results of the test conducted
by using the "Sanwa-made testers SP-10 / SP-150" (analog
meter).
• Use of other testers than those above may show different
measured results.
9Y1210318ENS0031US0
Ignition timing Factory spec.
0.34 to 0.40 rad
(19 to 23 °) before T.D.C at
3600 min-1 (rpm)
(1) Flywheel
(2) Rear End Plate
(3) Mark
(4) Ignition Timing
(5) Tamper Resistance
Resistance Factory spec. A - B 1.85 to 2.45 kΩ at 20 °C
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S26
Spark Test
1. Remove the spark plug, put it inside the high voltage cord cap
firmly, and then ground the threaded section to the engine body
(not to painted or resin parts).
2. Rotate the starter with the key switch and check that the plug
sparks.
CAUTION
• This test is hazardous of electric shocks. Never use hand
or screwdriver to press the plug to ground it to the engine
body.
• Keep inflammable away from the engine.
9Y1210318ENS0032US0
Resistance of Ignition Coil
1. Disconnect the connector.
2. Measure the resistance with an ohmmeter.
3. If the resistance is not with in the factory specifications, replace
it.
NOTE
• This check sheet shows the results of the test conducted
by using the "FLUKE MULTMETER 110 SERIES" (digital
meter).
• Use of other testers than those above may show different
measured results.
9Y1210318ENS0033US0
Air Gap of Engine Speed Sensor for Electronic Governor
1. Measure the air gap with a feeler gauge.
2. If air gap differs from the factory specification, readjust the air
gap.
NOTE
• The described numerical value is the values of KBT parts.
• Checking sensor as described in the manual of sensor
maker.
• The described valve is the data of supply of kubota.
Follow the instruction of OEM for parts adopted by OEM.
9Y1210318ENS0034US0
Resistance of Engine Speed Sensor for Electronic Governor
1. Measure the resistance with an ohmmeter.
2. If the resistance is not with in the factory specifications, replace
it.
NOTE
• The described numerical value is the values of KBT parts.
• Checking sensor as described in the manual of sensor
maker.
• This check sheet shows the results of the test conducted
by using the "FLUKE MULTMETER 110 SERIES".
• The described valve is the data of supply of kubota.
Follow the instruction of OEM for parts adopted by OEM.
9Y1210318ENS0035US0
Resistance Factory spec.
A - B 1.87 to 2.53 Ω at 20 °C
A - C 10.4 to 15.6 kΩ at 20 °C
A : Terminal (+)
B : Terminal (−)
C : High Tension Cord
Air gap Factory spec. 0.80 to 1.2 mm0.032 to 0.047 in.
Resistance Factory spec. Approx. 2.15 kΩ
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S27
Resistance of Ignitor
1. Disconnect the connector.
2. Measure the resistance with an ohmmeter.
3. If the resistance is not with in the factory specifications, replace
it.
9Y1210318ENS0036US0
Ignitor Check Chart
NOTE
• This check sheet shows the results of the test conducted by using the "FLUKE MULTMETER 110 SERIES"
(digital meter).
• Use of other testers than those above may show different measured results.
9Y1210318ENS0037US0
Negative
Positive A B C D E F G H
A – 10 to 40 kΩ 10 to 40 kΩ 11 to 47 kΩ Infinity Infinity Infinity Infinity
B 10 to 40 kΩ – 0.33 to 1.3 kΩ 1.8 to 7.3 kΩ Infinity Infinity Infinity Infinity
C 10 to 40 kΩ 0.33 to 1.3 kΩ – 1.5 to 6.0 kΩ Infinity Infinity Infinity Infinity
D 11 to 47 kΩ 1.8 to 7.3 kΩ 1.5 to 6.0 kΩ – Infinity Infinity Infinity Infinity
E Infinity Infinity Infinity Infinity – Infinity Infinity Infinity
F 2 megohm(minimum)
2 megohm
(minimum)
2 megohm
(minimum)
2 megohm
(minimum) Infinity – Infinity Infinity
G 2 megohm(minimum)
2 megohm
(minimum)
2 megohm
(minimum)
2 megohm
(minimum) Infinity Infinity – Infinity
H 2 megohm(minimum)
2 megohm
(minimum)
2 megohm
(minimum)
2 megohm
(minimum) Infinity Infinity Infinity –
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S28
(6) Electrical System
Motor Test
CAUTION
• Secure the starter to prevent it from jumping up and down
while testing the motor.
1. Disconnect the battery negative cable from the battery.
2. Disconnect the battery positive cable from the battery.
3. Disconnect the leads from the starter B terminal.
4. Remove the starter from the engine.
5. Connect a jumper lead from the starter C terminal (1) to the
battery positive terminal (2).
6. Connect a jumper lead momentarily between the starter's body
and the battery negative terminal (3).
7. If the motor does not run, starter is failure.
Repair or replace the starter.
NOTE
• B terminal : It is the terminal which connects the cable from
the battery to the starter.
• C terminal : It is the terminal which connects the cable from
the motor to the magnet switch.
9Y1210318ENS0038US0
Magnetic Switch Test
1. Disconnect the battery negative cable from the battery.
2. Disconnect the battery positive cable from the battery.
3. Disconnect the leads from the starter B terminal.
4. Remove the starter from the engine.
5. Connect a jumper lead from the starter S terminal (1) to the
battery positive terminal (2).
6. Connect a jumper lead momentarily between the starter's body
and the battery negative terminal (3).
7. If the pinion gear does not pop out, the magnetic switch is
failure. Repair or replace the starter.
NOTE
• B terminal : It is the terminal which connects the cable from
the battery to the starter.
• S terminal : It is the terminal which connects the cable from
the starter switch to the magnet switch.
9Y1210318ENS0039US0
Magnet Switch Continuity Test
1. Check the continuity across the C terminal (1) and the B
terminal (2) with a circuit tester, pushing in the plunger.
2. If not continuous or if a certain value is indicated, replace the
magnet switch.
9Y1210318ENS0040US0
(1) C Terminal
(2) Positive Terminal
(3) Negative Terminal
(1) S Terminal
(2) Positive Terminal
(3) Negative Terminal
(1) C Terminal (2) B Terminal
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S29
No-load Dynamo Output
1. Disconnect the lead wires from the dynamo.
2. Start the engine and operate the dynamo at the specified speed.
3. Measure the output voltage with a volt meter.
If the measurement is not within the specified values, replace
the dynamo.
9Y1210318ENS0041US0
Regulator
1. The engine is started.
2. Measure the output voltage of the regulator with the voltmeter.
3. When the measurement is not the above table value, measure
the input voltage of the regulator with the voltmeter.
4. When the measurement is the above table value, the regulator
is failure. Exchange it.
NOTE
• When the input voltage of the regulator is out of
specification, check the generator.
9Y1210318ENS0042US0
Alternator on Unit Test
(Before testing)
• Before alternator on unit test, check the battery terminal
connections, circuit connection, fan belt tension, charging
indicator lamp, fuses on the circuit, and abnormal noise from the
alternator.
• Prepare full charged battery for the test.
NOTE
• Be careful not to touch the rotating engine parts while
engine is running.
Keep safety distance from the engine rotating parts.
1. Start the engine.
2. When the engine is operating measure the voltage between two
battery terminals. If the voltage is between 13.8 V and 14.8 V,
the alternator is operating normally.
3. If the results of alternator on unit test are not within the
specifications, disassemble the alternator and check the each
component part for finding out the failure. See the
"DISASSEMBLING AND ASSEMBLING" and "SERVICING" for
alternator.
9Y1210318ENS0043US0
No-load output voltage Factory spec. AC 20 V or more at5200 min-1 (rpm)
Output voltage (6) - (2) 14 V to 15 V
Input voltage (1) - (3) Dynamo output voltage
(1) Terminal (Sky Blue)
(2) Terminal (Black)
(3) Terminal (Sky Blue)
(4) Terminal (Green)
(5) Terminal (Yellow)
(6) Terminal (Red)
Regulating voltage at no
load Factory spec.
13.8 to 14.8 V at 25 °C
(77 °F)
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S30
Fuel Cut Off Solenoid
1. Disconnect the connector.
2. Measure the resistance with an ohmmeter between the
connector terminals.
3. If the factory specification is not indicated the solenoid is faulty.
9Y1210318ENS0044US0
(7) Electronic Governor
Adjust Governor Lever
1. Loosen the idling speed screw (1).
2. Loosen the governor lever nut (4).
3. Turn the actuator shaft (3) fully counterclockwise.
4. Turn the governor lever (5) fully counterclockwise.
5. Tighten the governor lever nut (4) to the torque value.
NOTE
• Align governor lever (5) with pin hole of actuator shaft (A)
and tighten nut (4).
• When starter switch turned on, the actuator will be in
position control at the configured minimum position.
9Y1210318ENS0045US0
WG972-E2, DF972-E2 :
for Gasoline Factory spec. Approx. 38 Ω at 20 °C
DF972-E2 : for LPG Factory spec. Approx. 28 Ω at 20 °C
(1) Fuel Cut off Solenoid for Gasoline (2) Fuel Cut off Solenoid for LPG
Tightening torque Governor lever nut
9.81 to 11.2 N·m
1.00 to 1.15 kgf·m
7.24 to 8.31 lbf·ft
(1) Idle Adjust Screw
(2) Actuator
(3) Actuator Shaft
(4) Governor Lever Nut
(5) Governor Lever
A : Setting Position
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S31
Adjust Throttle Lever
CAUTION
• Do not overrunning the engine because the electronic
governor does not operate.
• The adjustment of the idle speed due to this process is not
an adjustment of the final product.
1. Disconnect actuator connector (1).
2. Start the engine while holding the throttle lever (2) at the idle
position by finger.
3. Adjust the engine speed with the idle adjust screw (3) to 1200
min-1 (rpm).
NOTE
• An electronic governor controls the engine speed between
1500 min-1 (rpm) and 3600 min−1 (rpm) though it depends on
the applications.
9Y1210318ENS0046US0
[2] DISASSEMBLING AND ASSEMBLING
IMPORTANT
• When reassembling, replace all of the O-rings and gaskets by new ones.
• When disassembling the LPG engine after completely consuming the fuel in piping.
9Y1210318ENS0047US0
(1) Draining Coolant and Engine Oil
Draining Engine Oil
1. Start and warm up the engine for approx. 5 minutes.
2. Place an oil pan underneath the engine.
3. Remove the drain plug (1) to drain oil.
4. After draining, screw in the drain plug.
(When refilling)
• Fill the engine oil up to the upper line on the dipstick (2).
IMPORTANT
• When using an oil of different maker or viscosity from the
previous one, remove all of the old oil.
• Never mix two different types of oil.
• Engine oil should have properties of API classification SH.
• Use the proper SAE Engine Oil according to ambient
temperature.
9Y1210318ENS0048US0
(1) Actuator Connector
(2) Throttle Lever
(3) Idle Adjust Screw
Above 25 °C (77 °F) SAE30 or SAE10W-30
0 °C to 25 °C (32 °F to 77 °F) SAE20 or SAE10W-30
Below 0 °C (32 °F) SAE10W or SAE10W-30
Engine oil capacity 3.4 L0.90 U.S.gals
Tightening torque Drain plug
33 to 37 N·m
3.3 to 3.8 kgf·m
24 to 27 lbf·ft
(1) Drain Plug (2) Dipstick
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S32
Draining Coolant
CAUTION
• Never remove radiator cap while operating or immediately
after stopping. Otherwise, hot water will spout out from the
radiator. Wait for more than ten minutes to cool the
radiator, before opening the cap.
1. Prepare a bucket. Open the coolant drain cock.
9Y1210318ENS0049US0
(2) External Components
Alternator, Starter and Others
1. Remove the air cleaner and muffler.
2. Remove the cooling fan (1), fan pulley and fan belt (2).
3. Remove the alternator.
4. Remove the starter.
(When reassembling)
• Check to see that there are no cracks on the belt surface.
IMPORTANT
• After reassembling the fan belt, be sure to adjust the fan
belt tension.
• Do not confuse the direction of the fan.
9Y1210318ENS0050US0
Fuel Line (WG972-E2)
1. Disconnect the gasoline hose from the connector (1).
9Y1210318ENS0051US0
LPG Hose and Coolant Hose (DF972-E2)
CAUTION
• Vent the air of the water passage of vaporizer (3) after
detaching the coolant hose (5).
1. Disconnect the LPG hose from the connector (4).
2. Disconnect the coolant hose (5).
3. Disconnect the vapor hose (2) and vacuum lock hose (1).
4. Remove the vaporizer (3) (if necessary).
IMPORTANT
• When disassembling the fuel system, make sure that the
fuel valve is closed.
(When reassembling)
• Bleed the vaporizer after supplying coolant.
9Y1210318ENS0052US0
(1) Coolant Drain Cock
(1) Cooling Fan (2) Fan Belt
(1) Gasoline Hose Connector
(1) Vacuum Lock Hose
(2) Vapor Hose
(3) Vaporizer
(4) LPG Hose Connector
(5) Coolant Hose
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S33
Gas Hose (DG972-E2)
1. Disconnect the gas hose from the connector.
2. Disconnect the gas hose (2) between the regulator (3) and gas
mixer (1).
3. Remove the regulator (3) (if necessary).
IMPORTANT
• When disassembling the fuel system, make sure that the
fuel valve closed.
9Y1210318ENS0053US0
Carburetor (Mechanical Governor) (WG972-E2, DF972-E2)
1. Disconnect the connector of LPG solenoid (for DF972) (4) and
the connector of gasoline solenoid (3).
2. Disconnect the breather hose (1).
3. Remove the air cleaner flange (2) and air cleaner gasket.
4. Disconnect the governor rod (6) from the carburetor (7) and
remove the carburetor (7).
5. Remove the carburetor flange and gasket.
NOTE
• Do not bend the governor rod (6), when disassembling and
assembling the carburetor (7).
• Do not stretch the governor rod spring (5) when
disassembling and assembling the carburetor (7).
9Y1210318ENS0054US0
Governor Lever and Carburetor (Electronic Governor)
(WG972-E2, DF972-E2)
1. Disconnect the connector of LPG solenoid (for DF972) and the
connector of gasoline solenoid.
2. Loosen the governor lever nut.
3. Remove the governor lever (7) with governor rod (5) and
governor rod spring (6).
4. Disconnect the breather hose (3).
5. Remove the air cleaner flange (2) and air cleaner gasket.
6. Remove the carburetor (4).
7. Remove the carburetor flange (8) and gasket.
NOTE
• Do not bend the governor rod (5), when disassembling and
assembling the carburetor (4).
• Do not stretch the governor rod spring (6) when
disassembling and assembling the carburetor (4).
9Y1210318ENS0055US0
(1) Gas Mixer
(2) Gas Hose
(3) Regulator
Tightening torque Carburetor mounting nut
24 to 27 N·m
2.4 to 2.8 kgf·m
18 to 20 lbf·ft
(1) Breather Hose
(2) Air Cleaner Flange
(3) Gasoline Solenoid Connector
(4) LPG Solenoid Connector
(5) Governor Rod spring
(6) Governor Rod
(7) Carburetor
Tightening torque Carburetor mounting nut
24 to 27 N·m
2.4 to 2.8 kgf·m
18 to 20 lbf·ft
(1) Actuator
(2) Air Cleaner Flange
(3) Breather Hose
(4) Carburetor
(5) Governor Rod
(6) Governor Rod Spring
(7) Governor Lever
(8) Carburetor Flange
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S34
Gas Mixer (DG972-E2)
1. Disconnect the breather hose (1).
2. Remove the air cleaner flange (2) and air cleaner gasket.
3. Disconnect the governor rod (5) and governor rod spring (4)
from the gas mixer (3).
4. Remove the gas mixer (3).
5. Remove the carburetor flange and gasket.
NOTE
• Do not bend the governor rod (5), when disassembling and
assembling the gas mixer (3).
• Do not stretch the governor rod spring (4) when
disassembling and assembling the gas mixer (3).
9Y1210318ENS0056US0
Adjust Governor Lever (Electronic Governor) (WG972-E2,
DF972-E2)
1. Loosen the idling speed screw (1).
2. Loosen the governor lever nut (4).
3. Turn the actuator shaft (3) fully counterclockwise.
4. Turn the governor lever (5) fully counterclockwise.
5. Tighten the governor lever nut (4) to the torque value.
NOTE
• Align governor lever (5) with pin hole of actuator shaft (A)
and tighten nut (4).
• When starter switch turned on, the actuator will be in
position control at the configured minimum position.
9Y1210318ENS0057US0
Tightening torque Gas mixer mounting nut
24 to 27 N·m
2.4 to 2.8 kgf·m
18 to 20 lbf·ft
(1) Breather Hose
(2) Air Cleaner Flange
(3) Gas Mixer
(4) Governor Rod Spring
(5) Governor Rod
Tightening torque Governor lever nut
9.81 to 11.2 N·m
1.00 to 1.15 kgf·m
7.24 to 8.31 lbf·ft
(1) Idle Adjust Screw
(2) Actuator
(3) Actuator Shaft
(4) Governor Lever Nut
(5) Governor Lever
A : Setting Position
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S35
Adjust Throttle Lever (Electronic Governor)
(WG972-E2, DF972-E2)
CAUTION
• Hold the throttle lever (2) by finger in the direction of the
engine speed reduction so as not to overrun.
• The adjustment of the idle speed due to this process is not
an adjustment of the final product.
1. Disconnect the connector (1) from actuator.
2. Start the engine while holding the throttle lever (2) at the idle
position by hand.
3. Adjust the engine speed with the idle adjust screw (3) to 1200
min-1 (rpm).
NOTE
• An electronic governor controls the engine speed between
1500 min-1 (rpm) and 3600 min−1 (rpm) through it depends
on the applications.
9Y1210318ENS0058US0
Actuator (Electronic Governor) (WG972-E2, DF972-E2)
1. Remove the actuator mounting screw (1).
2. Remove the actuator (2).
3. Remove the actuator flange screw (4).
4. Remove the actuator flange (3).
CAUTION
• All electronic equipment is static-sensitive, some
components more than others.
• To protect these components from static damage, you
must take special precautions to minimize or eliminate
electrostatic discharges.
9Y1210318ENS0059US0
(1) Connector
(2) Throttle Lever
(3) Idle Adjust Screw
Tightening torque
Actuator mounting screw
4.5 to 5.3 N·m
0.45 to 0.55 kgf·m
3.3 to 3.9 lbf·ft
Actuator flange screw
9.81 to 11.2 N·m
1.00 to 1.15 kgf·m
7.24 to 8.31 lbf·ft
(1) Actuator Mounting Screw
(2) Actuator
(3) Actuator Flange
(4) Actuator Flange Screw
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S36
Governor Lever
1. Disconnect the governor rod (2) and rod spring (1) from
governor lever (3).
2. Disconnect the governor spring (4) from governor lever.
3. Loosen the governor lever nut (6).
4. Remove the governor lever (3) from governor lever shaft (5).
(When reassembling)
• Loosen the governor lever nut (6).
• Set the throttle valve to the fully "OPEN" position with the
governor lever (3), turn the groove on the governor lever shaft
(5) fully clockwise with a screwdriver (to open the governor
completely), and then tighten the nut (6) in this position.
IMPORTANT
• After assembly of engine is completed, the adjustment of
governor is executed.
• Insert the governor lever to the position 2 mm (0.08 in.) (B)
away from the governor lever shaft end.
9Y1210318ENS0060US0
Tightening torque Governor lever nut
9.81 to 11.2 N·m
1.00 to 1.15 kgf·m
7.24 to 8.31 lbf·ft
(1) Governor Rod Spring
(2) Governor Rod
(3) Governor Lever
(4) Governor Spring
(5) Governor Lever Shaft
(6) Governor Lever Nut
A : Open Direction
B : 2 mm (0.08 in.)
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S37
Ignition Coil and Spark Plug
1. Disconnect the plug cap (1).
2. Disconnect the connector of ignition coil (3).
3. Remove the ignition coil (2).
A : for No. 1 cylinder
B : for No. 2 cylinder
C : for No. 3 cylinder
4. Remove the spark plug (4).
9Y1210318ENS0061US0
(3) Cylinder Head, Valves and Oil Pan
Cylinder Head Cover
1. Remove the head cover screws (1).
2. Remove the cylinder head cover (2).
3. Remove the intake manifold (3).
(When reassembling)
• Check to see if the cylinder head cover gasket is not defective.
9Y1210318ENS0062US0
(1) Plug Cap
(2) Ignition Coil
(3) Ignition Coil Connector
(4) Spark Plug
Tightening torque Cylinder head cover screw
9.81 to 11.2 N·m
1.00 to 1.15 kgf·m
7.24 to 8.31 lbf·ft
(1) Head Cover Screws
(2) Cylinder Head Cover
(3) Intake Manifold
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S38
Rocker Arm and Push Rod
1. Remove the rocker arm bracket screws (1).
2. Detach the rocker arm assembly (2).
3. Remove the push rods (3).
(When reassembling)
• When putting the push rods (3) onto the tappets (4), check to
see if their ends are properly engaged with the dimples.
IMPORTANT
• After installing the rocker arm, be sure to adjust the valve
clearance.
9Y1210318ENS0063US0
Cylinder Head
1. Loosen the pipe clamps (2), and remove the water return hose
(1).
2. Remove the cylinder head screw in the order of (n) to (a).
3. Lift up the cylinder head to detach.
4. Remove the cylinder head gasket.
(When reassembling)
• Replace the cylinder head gasket with a new one.
• Tighten the cylinder head screws after applying sufficient oil.
• Tighten the cylinder head screws in order of (a) to (n).
• Tighten them uniformly, or the head may deform in the long run.
9Y1210318ENS0064US0
Tappets
1. Remove the tappets (1) from the crankcase.
(When reassembling)
• Visually check the contact between tappets and cams for proper
rotation. If defect is found, replace tappets.
• Before installing the tappets, apply engine oil thinly around
them.
IMPORTANT
• Do not change the combination of tappet and tappet guide.
9Y1210318ENS0065US0
Tightening torque Rocker arm bracket screw
12 to 14 N·m
1.2 to 1.5 kgf·m
8.7 to 10 lbf·ft
(1) Rocker Arm Bracket Screws
(2) Rocker Arm Assembly
(3) Push Rod
(4) Tappet
Tightening torque Cylinder head screw
40 to 44 N·m
4.0 to 4.5 kgf·m
29 to 32 lbf·ft
(1) Water Return Hose
(2) Hose Clamp
A : Gear Case Side
(n) to (a) : To Loosen
(a) to (n) : To Tighten
(1) Tappet
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S39
Valves
1. Remove the valve caps (2).
2. Remove the valve spring collet (3), pushing the valve spring
retainer (4) with valve spring replacer (1).
3. Remove the valve spring retainer (4), valve spring (5) and valve
stem seal (6).
4. Remove the valve (7).
(When reassembling)
• Wash the valve stem and valve guide hole, and apply engine oil
sufficiently.
• After installing the valve spring collets, lightly tap the stem to
assure proper fit with a plastic hammer.
• Install a new stem seal on the valve guide (9) vertically with a jig
(8) when insert the stem seal (6). (See page G-29: "Valve Stem
Seal Replacing Tool".)
IMPORTANT
• Be sure stem seal (6) seats firmly against groove (10) on
valve guide.
• Use care to prevent damage to lip of stem seal and valve
stem when detach the valve spring collet by compressing
the valve spring.
• Do not change the combination of valve and valve guide.
9Y1210318ENS0066US0
(1) Valve Spring Replacer
(2) Valve Cap
(3) Valve Spring Collet
(4) Valve Spring Retainer
(5) Valve Spring
(6) Valve Stem Seal
(7) Valve
(8) Jig
(9) Valve Guide
(10) Groove of Valve Guide
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S40
Oil Pan and Oil Strainer
1. Remove the oil pan mounting screws (2).
2. Remove the oil pan (1) by lightly tapping the rim of the pan with
a wooden hammer.
3. Remove the oil strainer (3).
(When reassembling)
• After cleaning the oil strainer, check to see that the filter mesh
in clean, and install it.
• Visually check the O-ring (4), apply engine oil, and install it.
• Securely fit the O-ring to the oil strainer.
• To avoid uneven tightening, tighten oil pan mounting screws in
diagonal order form the center.
• Using the hole (5) numbered "3", install the oil strainer by
mounting screw.
IMPORTANT
• Scrape off the old adhesive completely. Wipe the sealing
surface clean. Now apply new adhesive 3.0 to 5.0 mm (0.12
to 0.19 in.) thick all over the contact surface. Apply the
adhesive also on the center of the flange as well as on the
inner wall of each bolt hole.
• Cut the nozzle of the "liquid gasket" (Three Bond 1207D or
equivalent) container at its second notch. Apply "liquid
gasket" about 5.0 mm (0.19 in.) thick.
Within 20 minutes after the application of fluid sealant,
reassemble the components. Wait then for about 30
minutes, and pour oil in the crankcase.
9Y1210318ENS0067US0
(4) Thermostat
Thermostat Assembly
1. Remove the thermostat cover mounting screws (1), and remove
the thermostat cover (2).
2. Remove the thermostat assembly (4).
(When reassembling)
• Apply a liquid gasket (Three Bond 1215 or equivalent) only at
the thermostat cover side of the gasket (3).
9Y1210318ENS0068US0
(1) Oil Pan
(2) Oil Pan Mounting Screw
(3) Oil Strainer
(4) O-ring
(5) Hole Numbered "3"
(1) Thermostat Cover Mounting Screw
(2) Thermostat Cover
(3) Thermostat Cover Gasket
(4) Thermostat Assembly
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S41
(5) Timing Gear, Camshaft and Fuel Camshaft
Speed Control Plate
1. Remove the screws (1) and separate the speed control plate
(2).
(When reassembling)
• Remove the speed control plate (for mechanical governor only)
(2) and make sure that the governor lever shaft (3) is correctly
set in the governor fork (4).
NOTE
• Electronic governor specification engine has modified
from speed control plate to cover plate.
9Y1210318ENS0069US0
Fan Drive Pulley
1. Secure the flywheel to keep it from turning.
2. Remove the fan drive pulley screw.
3. Draw out the fan drive pulley with a puller.
(When reassembling)
• Install the pulley to the crankshaft, aligning the mark (1) on
them.
• Apply engine oil to the fan drive pulley retaining screws. And
tighten them.
9Y1210318ENS0070US0
Gear Case
1. Remove the screw (1) of inside the gear case and outside
screws.
2. Remove the gear case (2).
(When reassembling)
• Apply a liquid gasket (Three Bond 1215 or equivalent) to both
sides of the gear case gasket.
• Be sure to set three O-rings inside the gear case.
9Y1210318ENS0071US0
(1) Screws and Copper Washers
(2) Speed Control Plate
(3) Governor Lever Shaft
(4) Governor Fork
Tightening torque Fan drive pulley screw
118 to 127 N·m
12.0 to 13.0 kgf·m
86.8 to 94.0 lbf·ft
(1) Alignment Mark
(1) Screw (Inside) (2) Gear Case
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S42
Water Pump Assembly
1. Remove the water pump assembly (2) from the gear case
cover.
(When reassembling)
• Apply a liquid gasket (Three Bond 1215 or equivalent) to both
sides of water pump gasket (3).
9Y1210318ENS0072US0
Idle Gear
1. Remove the external snap ring (1), the collar (3) and the idle
gear (2).
2. Remove the idle gear shaft mounting screws (4).
3. Remove the idle gear shaft (5).
(When reassembling)
• Apply engine oil to the idle gear shaft mounting screw (4). And
tighten them.
• Install the idle gear, aligning the mark (6) on the gears referring
to the photo.
9Y1210318ENS0073US0
Camshaft
1. Remove the camshaft mounting screws (1) and draw out the
camshaft with gear (2) on it.
(When reassembling)
• When install the camshaft, apply engine oil to the camshaft
journals.
• Apply engine oil to the camshaft mounting screws. And tighten
them.
9Y1210318ENS0074US0
(1) Water Pump Flange
(2) Water Pump Assembly
(3) Water Pump Gasket
Tightening torque Idle gear shaft mounting screw
9.81 to 11.2 N·m
1.00 to 1.15 kgf·m
7.24 to 8.31 lbf·ft
(1) External Snap Ring
(2) Idle Gear
(3) Idle Gear Collar
(4) Idle Gear Shaft Mounting Screw
(5) Idle Gear Shaft
(6) Alignment Mark
(1) Camshaft Mounting Screw (2) Camshaft Gear
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S43
Fuel Camshaft
1. Remove the retaining plate (4).
2. Remove the fork lever holder (for mechanical governor only)
mounting screws (6), then draw out the injection pump gear (1)
and fuel camshaft (5) with the governor fork assembly.
NOTE
• Electronic governor specification engine does not install
the fork lever (3) and governor assembly.
9Y1210318ENS0075US0
Oil Pump and Crankshaft Gear
1. Remove the oil pump gear (5).
2. Remove the oil pump (6).
3. Remove the collar (3), O-ring (4) and crankshaft oil slinger (2).
(When reassembling)
• Install the collar (3) after aligning the marks on the gear.
9Y1210318ENS0076US0
(6) Piston and Connecting Rod
Connecting Rod Cap
1. Remove the connecting rod caps (1) using a hexagonal 8 mm
socket.
(When reassembling)
• Align the marks (a) with each other. (Face the marks toward the
intake manifold.)
• Apply engine oil to the connecting rod screws and lightly screw
it in by hand, then tighten it to the specified torque.
If the connecting rod screw won't be screwed in smoothly, clean
the threads.
If the connecting rod screw is still hard to screw in, replace it.
9Y1210318ENS0077US0
(1) Injection Pump Gear
(2) Governor Sleeve
(3) Fork Lever
(4) Retaining Plate
(5) Fuel Camshaft
(6) Fork Lever Holder Mounting Screw
(1) Crankshaft Gear
(2) Crankshaft Oil Slinger
(3) Crankshaft Collar
(4) O-ring
(5) Oil Pump Gear
(6) Oil Pump
Tightening torque Connecting rod screw
27 to 30 N·m
2.7 to 3.1 kgf·m
20 to 22 lbf·ft
(1) Connecting Rod Cap (a) Mark
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S44
Piston
1. Turn the flywheel and bring the piston to top dead center.
2. Draw out the piston upward by lightly tapping it from the bottom
of the crankcase with the grip of a hammer.
3. Draw out the other pistons after the same method as above.
(When reassembling)
• Before inserting the piston into the cylinder, apply enough
engine oil to the piston.
• When inserting the piston into the cylinder, face the mark on the
connecting rod to the fuel camshaft.
• When inserting the piston into the cylinder, place the gap "C" of
the top compression ring on the opposite side of the slant
portion, and stagger the gaps "A", "E" of the second
compression ring and spacer making 2.09 rad (120 °) from the
gap of the top compression ring. Further, stagger the gaps "D",
"B" of the upper and lower side rail making 1.6 rad (90 °) from
the gap of the spacer.
IMPORTANT
• Do not change the combination of cylinder and piston.
Make sure of the position of each piston by marking. For
example, mark "1" on the No. 1 piston.
• When installing the piston into the cylinder, place the gaps
of all of the piston rings as shown in the figure.
• Carefully insert the piston using a piston ring compressor
(1). Otherwise, their chrome-plated section may be
scratched, causing trouble inside the cylinder.
9Y1210318ENS0078US0
Piston Ring and Connecting Rod
1. Remove the piston rings using a piston ring tool.
2. Remove the piston pin (10), and separate the connecting rod (8)
from the piston (7).
(When reassembling)
• When installing the second compression ring (2), assemble the
rings so that the manufacturer's mark (11) near the gap faces
the top of the piston.
• Apply engine oil to the piston pin.
• When installing the connecting rod to the piston, immerse the
piston in 80 °C (176 °F) oil for 10 to 15 minutes and insert the
piston pin to the piston.
• When installing the connecting rod to the piston, align the mark
(9) on the connecting rod to the plug recess (6).
IMPORTANT
• Mark the same number on the connecting rod and the
piston so as not to change the combination.
9Y1210318ENS0079US0
(1) Piston Ring Compressor
A : Second Compression Ring Gap
B : Side Rail Gap
C : Top Compression Ring Gap
D : Side Rail Gap
E : Spacer Gap
(a) 2.09 rad (120 °)
(b) 1.6 rad (90 °)
(1) Top Ring
(2) Second Ring
(3) Side Rail
(4) Spacer
(5) Piston Pin Snap Ring
(6) Plug Recess
(7) Piston
(8) Connecting Rod
(9) Mark
(10) Piston Pin
(11) Manufacturer's Mark
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S45
(7) Crankshaft
Flywheel
1. Secure the flywheel to keep it from turning using a flywheel
stopper.
2. Remove all flywheel screws (1) and then remove the flywheel
(2).
(When reassembling)
• Align the "1TC" mark (a) on the outer surface of the flywheel
horizontally with the alignment mark (b) on the rear end plate.
Now fit the flywheel in position.
• Apply engine oil to the threads and the undercut surface of the
flywheel screw and fit the screw.
9Y1210318ENS0080US0
Bearing Case Cover
1. Remove the bearing case cover mounting screws. First, remove
inside screws (1) and then outside screws (2).
2. Remove the bearing case cover (6).
(When reassembling)
• Fit the bearing case gasket (3) and the bearing case cover
gasket (4) with correct directions.
• Install the bearing case cover (6) to position the casting mark
"UP" (a) on it upward.
• Apply engine oil to the oil seal (5) lip and take care that it is not
rolled when installing.
• Tighten the bearing case cover mounting screws with even
force on the diagonal line.
9Y1210318ENS0081US0
Tightening torque Flywheel screw
54 to 58 N·m
5.5 to 6.0 kgf·m
40 to 43 lbf·ft
(1) Flywheel Screw
(2) Flywheel
(a) 1TC Mark
(b) Alignment Mark
Tightening torque Bearing case cover mounting screw
9.81 to 11.2 N·m
1.00 to 1.15 kgf·m
7.24 to 8.31 lbf·ft
(1) Bearing Case Cover Mounting
Screw (Inside)
(2) Bearing Case Cover Mounting
Screw (Outside)
(3) Bearing Case Gasket
(4) Bearing Case Cover Gasket
(5) Oil Seal
(6) Bearing Case Cover
(a) Top Mark "UP"
(b) Upside
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S46
Crankshaft Assembly
1. Remove the main bearing case screw 2 (1).
2. Turn the crankshaft to set the crankpin of the third cylinder to the
bottom dead center. Then draw out the crankshaft until the
crankpin of the second cylinder comes to the center of the third
cylinder.
3. Turn the crankshaft by 2.09 rad (120 °) counterclockwise to set
the crankpin of the second cylinder to the bottom dead center.
Draw out the crankshaft until the crankpin of the first cylinder
comes to the center of the third cylinder.
4. Repeat the above steps to draw out all the crankshaft.
(When reassembling)
• Clean the oil passage of the crankshaft with compressed air.
• Install the crankshaft assembly, aligning the screw hole of main
bearing case screw 2 with the screw hole of crankcase.
• When tightening the main bearing case screw 2, apply oil to the
main bearing case screw 2 (1) and screw by hand before
tightening the specific torque. If not smooth to screw by hand,
align the screw holes between the crankcase and the main
bearing case.
9Y1210318ENS0082US0
Tightening torque Main bearing case screw 2
27 to 30 N·m
2.7 to 3.1 kgf·m
20 to 22 lbf·ft
(1) Main Bearing Case Screw 2 (a) Cut Place for Removing and
Installing the Crankshaft
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S47
Main Bearing Case Assembly
1. Remove the two main bearing case screws 1 (4), and remove
the main bearing case assembly 1 (1), being careful with
crankshaft bearing 3 (5) (9).
2. Remove the main bearing case assembly 2 (2) and the main
bearing case assembly (3) as above. Keep in mind, however,
that the thrust bearing (8) is installed in the main bearing case
assembly (3).
(When reassembling)
• Clean the oil passage in the main bearing cases.
• Apply clean engine oil to the bearings.
• Install the main bearing case assemblies in original positions.
Since diameters of main bearing cases vary, install them in
order of marking (b) from the gear case side. (Refer to the
figure.).
• Be careful not to confuse the top and bottom of the crankshaft
bearing 3 (5) (9). (Install the bearing with the oil groove (c) up.).
• Match the alignment numbers (a) on the main bearing case
assembly 1.
• Do the same for the main bearing case assembly 2 (2) and the
main bearing case assembly (3) too.
• When installing the main bearing case 1 and 2, face the mark
"FLYWHEEL" to the flywheel.
• Install the thrust bearing (8) with its oil groove facing outward.
• Confirm that the main bearing case moves smoothly after
tightening the main bearing case screw 1 to the specified
torque.
9Y1210318ENS0083US0
Tightening torque Main bearing case screw 1
13 to 15 N·m
1.3 to 1.6 kgf·m
9.4 to 11 lbf·ft
(1) Main Bearing Case Assembly 1
(2) Main Bearing Case Assembly 2
(3) Main Bearing Case Assembly
(4) Main Bearing Case Screw 1
(5) Crankshaft Bearing 3 (Upper, with
Oil Groove)
(6) Crankshaft Bearing 2
(Upper, with Oil Groove)
(7) Crankshaft Bearing 2
(Lower)
(8) Thrust Bearing
(9) Crankshaft Bearing 3 (Lower)
(a) Alignment Number
(b) Marking (1 or 2)
(c) Oil Groove
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S48
(8) Starter
1. Unscrew the C terminal nut (7), and disconnect the connecting lead (12).
2. Unscrew the solenoid switch mounting nuts (1), and remove the solenoid switch (5).
3. Remove the end frame cap (17).
4. Remove the brake shoe (16), brake spring (15) and gasket (14).
5. Unscrew the through bolts (22), and remove the rear end frame (13).
6. Remove the brush from the brush holder while holding the spring up.
7. Remove the brush holder (21).
8. Draw out the yoke (19) from the starter drive housing (2).
9. Draw out the armature (10) with the drive lever (3).
NOTE
• Do not damage to the brush and commutator.
(When reassembling)
• Apply grease (DENSO.CO.LTD. No. 50 or equivalent) to the parts indicated in the figure.
– Joint of solenoid switch (a)
– Bushing (b)
– Drive lever (c)
– Collar (d)
– Teeth of pinion gear (e)
– Armature shaft (f)
9Y1210318ENS0084US0
(1) Solenoid Switch Mounting
Nut
(2) Starter Drive Housing
(3) Drive Lever
(4) Gasket
(5) Solenoid Switch
(6) B Terminal Nut
(7) C Terminal Nut
(8) Snap Ring
(9) Overrunning Clutch
(10) Armature
(11) Brush Spring
(12) Connecting Lead
(13) Rear End Frame
(14) Gasket
(15) Brake Spring
(16) Brake Shoe
(17) End Frame Cap
(18) Screw
(19) Yoke
(20) Brush
(21) Brush Holder
(22) Through Bolt
Tightening torque Starter's terminal B mounting nut
5.9 to 11 N·m
0.60 to 1.2 kgf·m
4.4 to 8.6 lbf·ft
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S49
(9) Dynamo
1. Remove the nut and separate the plate (7).
2. Tap out the shaft (1) from the rotor (3).
3. Unscrew the screws and remove the stator (6).
(When reassembling)
• Take care the direction of the collar (4), the flat side should face to the pulley side.
9Y1210318ENS0085US0
(1) Shaft
(2) Pulley
(3) Rotor
(4) Collar
(5) Bearing
(6) Stator
(7) Plate
(8) Bearing
Tightening torque Dynamo's pulley nut
40 to 44 N·m
4.0 to 4.5 kgf·m
29 to 32 lbf·ft
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S50
(10) Alternator
1. Remove the pulley (1).
2. Remove the rear end cover (12).
3. Remove the brush holder (11).
4. Remove the IC regulator (10).
5. Remove the four screws holding the stator lead wires.
6. Remove the rectifier (9).
7. Remove the rear end frame (8).
8. Press out the rotor (6) from drive end frame (2).
9. Remove the retainer plate (5).
10. Press out the bearing (4) from drive end frame (2) with a press and jig.
11. Lightly secure the rotor with a vise to prevent damage, and remove the bearing (7) with a puller.
(When reassembling)
9Y1210318ENS0086US0
(1) Pulley
(2) Drive End Frame
(3) Stator
(4) Bearing
(5) Retainer Plate
(6) Rotor
(7) Bearing
(8) Rear End Frame
(9) Rectifier
(10) IC Regulator
(11) Brush Holder
(12) Rear End Cover
Tightening torque Alternator's pulley nut
58.4 to 78.9 N·m
5.95 to 8.05 kgf·m
43.1 to 58.2 lbf·ft
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S51
[3] SERVICING
(1) Cylinder Head and Valves
Cylinder Head Surface Flatness
1. Clean the cylinder head surface.
2. Place a straightedge on the cylinder head's four sides and two
diagonal as shown in the figure.
Measure the clearance with a feeler gauge.
3. If the measurement exceeds the allowable limit, correct it with a
surface grinder.
IMPORTANT
• Be sure to check the valve recessing after correcting.
9Y1210318ENS0087US0
Cylinder Head Flaw
1. Prepare an air spray red check.
2. Clean the surface of the cylinder head with the detergent (2).
3. Spray the cylinder head surface with the red permeative liquid
(1). Leave it five to ten minutes after spraying.
4. Wash away the red permeative liquid on the cylinder head
surface with the detergent (2).
5. Spray the cylinder head surface with the white developer (3).
6. If flawed, it can be identified as red marks.
9Y1210318ENS0088US0
Valve Recessing
1. Clean the cylinder head, the valve face and seat.
2. Insert the valve into the valve guide.
3. Measure the valve recessing with a depth gauge.
4. If the measurement exceeds the allowable limit, replace the
valve.
5. If it still exceeds the allowable limit after replacing the valve,
replace the cylinder head.
9Y1210318ENS0089US0
Cylinder head surface
flatness Allowable limit
0.05 mm
0.002 in.
(1) Red Permeative Liquid
(2) Detergent
(3) White Developer
Valve recessing (Intake
and Exhaust)
Factory spec.
0.10 (protrusion) to
0.10 (recessing) mm
0.0039 (protrusion) to
0.0039 (recessing) in.
Allowable limit 0.30 (recessing) mm0.012 (recessing) in.
(1) Cylinder Head Surface (A) Recessing
(B) Protrusion
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S52
Clearance between Valve Stem and Valve Guide
1. Remove carbon from the valve guide section.
2. Measure the valve stem O.D. with an outside micrometer.
3. Measure the valve guide I.D. with a small hole gauge, and
calculate the clearance.
4. If the clearance exceeds the allowable limit, replace the valves.
If it still exceeds the allowable limit, replace the valve guide.
9Y1210318ENS0090US0
Replacing Valve Guide
(When removing)
1. Press out the used valve guide using a valve guide replacing
tool.
(When installing)
1. Clean a new valve guide and valve guide bore, and apply
engine oil to them.
2. Press in a new valve guide using a valve guide replacing tool.
3. Ream precisely the I.D. of the valve guide to the specified
dimension.
IMPORTANT
• Do not hit the valve guide with a hammer during
replacement.
9Y1210318ENS0091US0
Clearance between
valve stem and valve
guide
Factory spec. 0.030 to 0.057 mm0.0012 to 0.0022 in.
Allowable limit 0.10 mm0.0039 in.
Valve stem O.D. Factory spec. 5.968 to 5.980 mm0.2350 to 0.2354 in.
Valve guide I.D. Factory spec. 6.010 to 6.025 mm0.2367 to 0.2372 in.
Valve guide I.D.(Intake
and exhaust) Factory spec.
6.010 to 6.025 mm
0.2367 to 0.2372 in.
(A) When Removing (B) When Installing
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S53
Valve Seating
1. Coat the valve face lightly with prussian blue and put the valve
on its seat to check the contact.
2. If the valve does not seat all the way around the valve seat or
the valve contact is less than 70 %, correct the valve seating as
follows.
3. If the valve contact does not comply with the reference value,
replace the valve or correct the contact of valve seating.
9Y1210318ENS0092US0
Valve seat width Factory spec. 2.12 mm0.0835 in.
(1) Correct
(2) Incorrect
(3) Incorrect
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S54
Correcting Valve and Valve Seat
NOTE
• Before correcting the valve and seat, check the valve stem
and the I.D. of valve guide section, and repair them if
necessary.
• After correcting the valve seat, be sure to check the valve
recessing.
1) Correcting Valve
1. Correct the valve with a valve refacer.
2) Correcting Valve Seat
1. Slightly correct the seat surface with a 0.79 rad (45 °) valve seat
cutter.
2. Fitting the valve, check the contact position of the valve face
and seat surface with prussian blue. (Visual check) [If the valve
has been used for a long period, the seat tends to come in
contact with the upper side of the valve face.]
3. Grind the upper surface of the seat with a 0.26 rad (15 °) valve
seat cutter until the valve seat touches to the center of the valve
face (so that (a) equals (b) as shown in the figure.)
4. Grind the seat with a 0.79 rad (45 °) valve seat cutter again, and
visually recheck the contact between the valve and seat.
5. Repeat steps 3 and 4 until the correct contact is achieved.
6. Continue lapping until the seated rate becomes more than 70 %
of the total contact.
9Y1210318ENS0093US0
Valve Lapping
1. Apply compound evenly to the valve lapping surface.
2. Insert the valve into the valve guide. Lap the valve onto its seat
with a valve flapper or screwdriver.
3. After lapping the valve, wash the compound away and apply oil,
then repeat valve lapping with oil.
4. Apply prussian blue to the contact surface to check the seated
rate. If it is less than 70 %, repeat valve lapping again.
IMPORTANT
• When valve lapping is performed, be sure to check the
valve recessing and adjust the valve clearance after
assembling the valve.
9Y1210318ENS0094US0
Valve face angle Factory spec. 0.79 rad45 °
Valve seat angle Factory spec. 0.79 rad45 °
(1) Valve Seat Cutter
(A) Check Contact
(B) Correct Seat Width
(C) Check Seat Surface
(D) Check Contact
(a) Identical Dimensions
(b) Valve Seat Width
(c) 0.26 rad (15 °)
(d) 0.79 rad (45 °)
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S55
Free Length and Tilt of Valve Spring
1. Measure the free length (B) of valve spring with vernier calipers.
If the measurement is less than the allowable limit, replace it.
2. Put the spring on a surface plate, place a square on the side of
the spring.
3. Check to see if the entire side is in contact with the square.
Rotate the valve spring and measure the maximum tilt (A).
If the measurement exceeds the allowable limit, replace it.
4. Check the entire surface of the valve spring for scratches.
If there is any defect, replace it.
9Y1210318ENS0095US0
Valve Spring Setting Load
1. Place the valve spring on a tester and compress it to the same
length it is actually compressed in the engine.
2. Read the compression load on the gauge.
3. If the measurement is less than the allowable limit, replace it.
9Y1210318ENS0096US0
Oil Clearance between Rocker Arm and Rocker Arm Shaft
1. Measure the rocker arm shaft O.D. with an outside micrometer.
2. Measure the rocker arm I.D. with an inside micrometer, and
then calculate the oil clearance.
3. If the oil clearance exceeds the allowable limit, replace the
rocker arm and measure the oil clearance again. If it still
exceeds the allowable limit, replace also the rocker arm shaft.
9Y1210318ENS0097US0
Tilt (A) Allowable limit 1.0 mm0.039 in.
Free length (B)
Factory spec. 31.3 to 31.8 mm1.24 to 1.25 in.
Allowable limit 28.4 mm1.12 in.
(A) Tilt (B) Free length
Setting load / setting
length
Factory spec.
65 N / 27.0 mm
6.6 kgf / 27.0 mm
15 lbf / 1.06 in.
Allowable limit
55 N / 27.0 mm
5.6 kgf / 27.0 mm
12 lbf / 1.06 in.
Oil clearance between
rocker arm and rocker
arm shaft
Factory spec. 0.016 to 0.045 mm0.00063 to 0.0017 in.
Allowable limit 0.15 mm0.0059 in.
Rocker arm shaft O.D. Factory spec. 10.473 to 10.484 mm0.41233 to 0.41275 in.
Rocker arm I.D. Factory spec. 10.500 to 10.518 mm0.41339 to 0.41409 in.
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S56
Push Rod Alignment
1. Place the push rod on V blocks.
2. Measure the push rod alignment.
3. If the measurement exceeds the allowable limit, replace the
push rod.
9Y1210318ENS0098US0
Oil Clearance between Tappet and Tappet Guide Bore
1. Measure the tappet O.D. with an outside micrometer.
2. Measure the I.D. of the tappet guide bore with a cylinder gauge,
and calculate the oil clearance.
3. If the oil clearance exceeds the allowable limit or the tappet is
damaged, replace the tappet.
9Y1210318ENS0099US0
(2) Timing Gear and Camshaft
Timing Gear Backlash
1. Set a dial indicator (lever type) with its tip on the gear tooth.
2. Move the gear to measure the backlash, holding its mating gear.
3. If the backlash exceeds the allowable limit, check the oil
clearance of the shafts and the gear.
4. If the oil clearance is proper, replace the gear.
9Y1210318ENS0100US0
Push rod alignment Allowable limit 0.25 mm0.0098 in.
Oil clearance between
tappet and tappet guide
bore
Factory spec. 0.016 to 0.052 mm0.00063 to 0.0020 in.
Allowable limit 0.10 mm0.0039 in.
Tappet O.D. Factory spec. 17.966 to 17.984 mm0.70733 to 0.70803 in.
Tappet guide bore I.D. Factory spec. 18.000 to 18.018 mm0.70867 to 0.70937 in.
Backlash between idle
gear and crank gear
Factory spec. 0.0430 to 0.124 mm0.00170 to 0.00488 in.
Allowable limit 0.15 mm0.0059 in.
Backlash between idle
gear and cam gear
Factory spec. 0.0470 to 0.123 mm0.00185 to 0.00484 in.
Allowable limit 0.15 mm0.0059 in.
Backlash between idle
gear and injection pump
gear
Factory spec. 0.0410 to 0.124 mm0.00162 to 0.00488 in.
Allowable limit 0.15 mm0.0059 in.
Backlash between oil
pump drive gear and
crank gear
Factory spec. 0.0410 to 0.123 mm0.00162 to 0.00484 in.
Allowable limit 0.15 mm0.0059 in.
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S57
Idle Gear Side Clearance
1. Set a dial indicator with its tip on the idle gear.
2. Measure the side clearance by moving the idle gear to the front
and rear.
3. If the measurement exceeds the allowable limit, replace the idle
gear collar.
9Y1210318ENS0101US0
Camshaft Side Clearance
1. Set a dial indicator with its tip on the camshaft.
2. Measure the side clearance by moving the cam gear to the front
and rear.
3. If the measurement exceeds the allowable limit, replace the
camshaft stopper.
9Y1210318ENS0102US0
Camshaft Alignment
1. Support the camshaft with V blocks on the surface plate at both
end journals.
2. Set a dial indicator with its tip on the intermediate journal.
3. Measure the camshaft alignment.
4. If the measurement exceeds the allowable limit, replace the
camshaft.
9Y1210318ENS0103US0
Cam Height
1. Measure the height of the cam at its highest point with an
outside micrometer.
2. If the measurement is less than the allowable limit, replace the
camshaft.
9Y1210318ENS0104US0
Idle gear side clearance
Factory spec. 0.20 to 0.51 mm0.0079 to 0.020 in.
Allowable limit 0.80 mm0.031 in.
Camshaft side clearance
Factory spec. 0.15 to 0.31 mm0.0059 to 0.012 in.
Allowable limit 0.50 mm0.020 in.
Camshaft alignment Allowable limit 0.01 mm0.0004 in.
Cam height of intake and
exhaust
Factory spec. 26.88 mm1.058 in.
Allowable limit 26.83 mm1.056 in.
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S58
Oil Clearance of Camshaft Journal
1. Measure the camshaft journal O.D. with an outside micrometer.
2. Measure the cylinder block bore I.D. for camshaft with a inside
micrometer, and calculate the oil clearance.
3. If the clearance exceeds the allowable limit, replace the
camshaft.
9Y1210318ENS0105US0
Oil Clearance between Idle Gear Shaft and Idle Gear Bushing
1. Measure the idle gear shaft O.D. with an outside micrometer.
2. Measure the idle gear bushings I.D. with an inside micrometer,
and calculate the oil clearance.
3. If the oil clearance exceeds the allowable limit, replace the
bushing.
4. If it still exceeds the allowable limit, replace the idle gear shaft.
9Y1210318ENS0106US0
Replacing Idle Gear Bushing
(When removing)
1. Press out the used idle gear bushing using an idle gear bushing
replacing tool.
(When installing)
1. Clean a new idle gear bushing and idle gear bore, and apply
engine oil to them.
2. Press in a new bushing using an idle gear bushing replacing
tool, until it is flush with the end of the idle gear.
9Y1210318ENS0107US0
Oil clearance of
camshaft journal
Factory spec. 0.050 to 0.091 mm0.0020 to 0.0035 in.
Allowable limit 0.15 mm0.0059 in.
Camshaft journal O.D. Factory spec. 32.934 to 32.950 mm1.2967 to 1.2972 in.
Camshaft bearing I.D.
(Cylinder block bore I.D.) Factory spec.
33.000 to 33.025 mm
1.2993 to 1.3001 in.
Oil clearance between
idle gear shaft and idle
gear bushing
Factory spec. 0.020 to 0.084 mm0.00079 to 0.0033 in.
Allowable limit 0.10 mm0.0039 in.
Idle gear shaft O.D. Factory spec. 19.967 to 19.980 mm0.78611 to 0.78661 in.
Idle gear bushing I.D. Factory spec. 20.000 to 20.051 mm0.78741 to 0.78940 in.
(A) When Removing (B) When Installing
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S59
(3) Piston and Connecting Rod
Piston Pin Bore I.D.
1. Measure the piston pin bore I.D. in both the horizontal and
vertical directions with a cylinder gauge.
2. If the measurement exceeds the allowable limit, replace the
piston.
9Y1210318ENS0108US0
Oil Clearance between Piston Pin and Small End Bushing
1. Measure the O.D. of the piston pin where it contacts the bushing
with an outside micrometer.
2. Measure the small end bushing I.D. with an inside micrometer,
and calculate the oil clearance.
3. If the oil clearance exceeds the allowable limit, replace the
bushing. If it still exceeds the allowable limit, replace the piston
pin.
9Y1210318ENS0109US0
Replacing Small End Bushing
(When removing)
1. Press out the used bushing using a small end bushing replacing
tool. (Refer to "SPECIAL TOOLS".)
(When installing)
1. Clean a new small end bushing and bore, and apply engine oil
to them.
2. Using a small end bushing replacing tool, press in a new
bushing (service parts) taking due care to see that the
connecting rod hole matches the bushing hole.
[Servicing parts dimension]
9Y1210318ENS0110US0
Piston pin bore I.D.
Factory spec. 20.000 to 20.013 mm0.78741 to 0.78791 in.
Allowable limit 20.05 mm0.7894 in.
Oil clearance between
piston pin and small end
bushing
Factory spec. 0.012 to 0.038 mm0.00048 to 0.0014 in.
Allowable limit 0.10 mm0.0039 in.
Piston pin O.D. Factory spec. 20.002 to 20.013 mm0.78748 to 0.78791 in.
Small end bushing I.D. Factory spec. 20.025 to 20.040 mm0.78839 to 0.78897 in.
Oil clearance between
piston pin and small end
bushing (Spare parts)
Factory spec. 0.013 to 0.075 mm0.00052 to 0.0029 in.
Allowable limit 0.15 mm0.0059 in.
Small end bushing I.D.
(Spare parts) Factory spec.
20.026 to 20.077 mm
0.78843 to 0.79043 in.
(1) Seam
(2) Oil Hole
(A) When Removing
(B) When Installing
(a) 0.79 rad (45 °)
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S60
Piston Ring Gap
1. Insert the piston ring into the lower part of the cylinder (the least
worn out part) with a piston ring compressor and piston.
2. Measure the ring gap with a feeler gauge.
3. If the measurement exceeds the allowable limit, replace the
piston ring.
9Y1210318ENS0111US0
Clearance between Piston Ring and Piston Ring Groove
1. Clean the rings and the ring grooves, and install each ring in its
groove.
2. Measure the clearance between the ring and the groove with a
thickness gauge.
3. If the clearance exceeds the allowable limit, replace the piston
ring.
4. If the clearance still exceeds the allowable limit with new ring,
replace the piston.
9Y1210318ENS0112US0
Connecting Rod Alignment
1. Remove the crankpin bearing, and install the connecting rod
cap.
2. Install the piston pin in the connecting rod.
3. Install the connecting rod on the connecting rod alignment tool.
4. Put a gauge over the piston pin, and move it against the face
plate.
5. If the gauge does not fit squarely against the face plate,
measure the space between the pin of the gauge and the face
plate.
6. If the measurement exceeds the allowable limit, replace the
connecting rod.
9Y1210318ENS0113US0
Piston ring gap
Top ring
Factory
spec.
0.15 to 0.35 mm
0.0059 to 0.013 in.
Allowable
limit
1.25 mm
0.0492 in.
Second
ring
Factory
spec.
0.30 to 0.45 mm
0.012 to 0.017 in.
Allowable
limit
1.25 mm
0.0492 in.
Oil ring
Factory
spec.
0.20 to 0.70 mm
0.0079 to 0.027 in.
Allowable
limit
1.25 mm
0.0492 in.
Clearance between
piston ring and piston
ring groove
Top ring
Factory
spec.
0.080 to 0.12 mm
0.0032 to 0.0047 in.
Allowable
limit
0.15 mm
0.0059 in.
Second
ring
Factory
spec.
0.065 to 0.10 mm
0.0026 to 0.0039 in.
Allowable
limit
0.15 mm
0.0059 in.
Oil ring
Factory
spec.
0.060 to 0.15 mm
0.0024 to 0.0059 in.
Allowable
limit
0.20 mm
0.0079 in.
Space between gauge
pin face plate Allowable limit
0.05 mm
0.002 in.
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S61
(4) Crankshaft
Crankshaft Side Clearance
1. Set a dial indicator with its tip on the end of the crankshaft.
2. Measure the side clearance by moving the crankshaft to the
front and rear.
3. If the measurement exceeds the allowable limit, replace the
thrust bearings.
4. If the same size bearing is useless because of the crankshaft
journal wear, replace it with an oversize one referring to the
table and figure.
(Reference)
• Oversize thrust bearing
• Oversize dimensions of crankshaft journal
9Y1210318ENS0114US0
Crankshaft Alignment
1. Support the crankshaft with V blocks on the surface plate at
both end journals.
2. Set a dial indicator with its tip on the intermediate journal.
3. Measure the crankshaft alignment.
4. If the measurement exceeds the allowable limit, replace the
crankshaft.
9Y1210318ENS0115US0
Crankshaft side
clearance
Factory spec. 0.15 to 0.31 mm0.0059 to 0.012 in.
Allowable limit 0.50 mm0.020 in.
Oversize Bearing Code Number Marking
0.2 mm
0.008 in.
Thrust bearing 1 02 15261-23950 020 OS
Thrust bearing 2 02 15261-23970 020 OS
0.4 mm
0.02 in.
Thrust bearing 1 04 15261-23960 040 OS
Thrust bearing 2 04 15261-23980 040 OS
Oversize 0.2 mm0.008 in.
0.4 mm
0.02 in.
Dimension A 46.10 to 46.30 mm1.815 to 1.822 in.
46.30 to 46.50 mm
1.823 to 1.830 in.
Dimension B 23.40 to 23.45 mm0.9213 to 0.9232 in.
23.60 to 23.65 mm
0.9292 to 0.9311 in.
Dimension C 1.8 to 2.2 mm radius0.071 to 0.086 in. radius
1.8 to 2.2 mm radius
0.071 to 0.086 in. radius
The crankshaft journal must be fine-finished to higher than Rmax = 0.8S
Crankshaft alignment Allowable limit 0.02 mm0.0008 in.
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S62
Oil Clearance between Crankpin and Crankpin Bearing
1. Clean the crankpin and crankpin bearing.
2. Put a strip of plastigage on the center of the crankpin.
3. Install the connecting rod cap and tighten the connecting rod
screws to the specified torque, and remove the cap again.
4. Measure the amount of the flattening with the scale, and get the
oil clearance.
5. If the oil clearance exceeds the allowable limit, replace the
crankpin bearing.
6. If the same size bearing is useless because of the crankpin
wear, replace it with an undersize one referring to the table and
figure.
NOTE
• Never insert the plastigage into the crankpin oil hole.
• Be sure not to move the crankshaft while the connecting
rod screws are tightened.
(Reference)
• Undersize crankpin bearing
• Undersize dimensions of crankpin
9Y1210318ENS0116US0
Oil clearance between
crankpin and crankpin
bearing
Factory spec. 0.020 to 0.051 mm0.00079 to 0.0020 in.
Allowable limit 0.15 mm0.0059 in.
Crankpin O.D. Factory spec. 33.959 to 33.975 mm1.3370 to 1.3375 in.
Crankpin bearing I.D. Factory spec. 33.995 to 34.010 mm1.3384 to 1.3389 in.
Undersize Bearing Code Number Marking
0.2 mm
0.008 in. Crankpin bearing 02 15861-22970 020 US
0.4 mm
0.02 in. Crankpin bearing 04 15861-20980 040 US
Undersize 0.2 mm0.008 in.
0.4 mm
0.02 in.
Dimension A 2.3 to 2.7 mm radius0.091 to 0.10 in. radius
2.3 to 2.7 mm radius
0.091 to 0.10 in. radius
*Dimension B 1.0 to 1.5 mm relief0.040 to 0.059 in. relief
1.0 to 1.5 mm relief
0.040 to 0.059 in. relief
Dimension C 33.759 to 33.775 mm dia.1.3291 to 1.3297 in. dia.
33.559 to 33.575 mm dia.
1.3213 to 1.3218 in. dia.
The crankpin journal must be fine-finished to higher than Rmax = 0.8S
*Holes to be de-burred and edges rounded with 1.0 to 1.5 mm
(0.040 to 0.059 in.) relief.
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S63
Oil Clearance between Crankshaft Journal and Crankshaft
Bearing 1
1. Measure the O.D. of the crankshaft front journal with an outside
micrometer.
2. Measure the I.D. of the crankshaft bearing 1 with an inside
micrometer, and calculate the oil clearance.
3. If the oil clearance exceeds the allowable limit, replace the
crankshaft bearing 1.
4. If the same size bearing is useless because of the crankshaft
journal wear, replace it with an undersize one referring to the
table and the figure.
(Reference)
• Undersize crankshaft bearing 1
• Undersize dimensions of crankshaft journal
9Y1210318ENS0117US0
Replacing Crankshaft Bearing 1
(When removing)
1. Press out the used crankshaft bearing 1 using a crankshaft
bearing 1 replacing tool.
(When installing)
1. Clean a new crankshaft bearing 1 and crankshaft journal bore,
and apply engine oil to them.
2. Using a crankshaft bearing 1 replacing tool, press in a new
bearing 1 (2) so that its seam (1) directs toward the exhaust
manifold side. (See figure.)
9Y1210318ENS0118US0
Oil Clearance between
crankshaft journal and
crankshaft bearing 1
Factory spec. 0.0340 to 0.106 mm0.00134 to 0.00417 in.
Allowable limit 0.20 mm0.0079 in.
Crankshaft journal O.D. Factory spec. 43.934 to 43.950 mm1.7297 to 1.7303 in.
Crankshaft bearing 1 I.D. Factory spec. 43.984 to 44.040 mm1.7317 to 1.7338 in.
Undersize Bearing Code Number Marking
0.2 mm
0.008 in. Crankshaft bearing 1 02 1G460-23910 020 US
0.4 mm
0.02 in. Crankshaft bearing 1 04 1G460-23920 040 US
Undersize 0.2 mm0.008 in.
0.4 mm
0.02 in.
Dimension A 1.8 to 2.2 mm radius0.071 to 0.086 in. radius
1.8 to 2.2 mm radius
0.071 to 0.086 in. radius
*Dimension B 1.0 to 1.5 mm relief0.040 to 0.059 in. relief
1.0 to 1.5 mm relief
0.040 to 0.059 in. relief
Dimension C 43.734 to 43.750 mm dia.1.7219 to 1.7224 in. dia.
43.534 to 43.550 mm dia.
1.7140 to 1.7145 in. dia.
The crankshaft journal must be fine-finished to higher than Rmax = 0.8S
*Holes to be de-burred and edges rounded with 1.0 to 1.5 mm
(0.040 to 0.059 in.) relief.
Dimension (A) Factory spec. 0 to 0.3 mm0 to 0.01 in.
(1) Seam
(2) Crankshaft Bearing 1
(3) Cylinder Block
(A) Dimension
(a) 0.37 rad (21 °)
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S64
Oil Clearance between Crankshaft Journal and Crankshaft
Bearing 2 (Crankshaft Bearing 3)
1. Put a strip of plastigage on the center of the journal.
2. Install the bearing case and tighten the bearing case screws 1
to the specified torque, and remove the bearing case again.
3. Measure the amount of the flattening with the scale, and get the
oil clearance.
4. If the oil clearance exceeds the allowable limit, replace the
crankshaft bearing 2 (crankshaft bearing 3).
5. If the same size bearing is useless because of the crankshaft
journal wear, replace it with an undersize one referring to the
table and figure.
NOTE
• Be sure not to move the crankshaft while the bearing case
screws are tightened.
(Reference)
• Undersize crankshaft bearing 2 and 3
• Undersize dimensions of crankshaft journal
9Y1210318ENS0119US0
Oil clearance between
crankshaft journal and
crankshaft bearing 2
(crankshaft bearing 3)
Factory spec. 0.028 to 0.059 mm0.0011 to 0.0023 in.
Allowable limit 0.20 mm0.0079 in.
Crankshaft journal O.D.
(Flywheel side) Factory spec.
43.934 to 43.950 mm
1.7297 to 1.7303 in.
Crankshaft bearing 2 I.D. Factory spec. 43.978 to 43.993 mm1.7315 to 1.7320 in.
Crankshaft journal O.D.
(Intermediate) Factory spec.
43.934 to 43.950 mm
1.7297 to 1.7303 in.
Crankshaft bearing 3 I.D. Factory spec. 43.978 to 43.993 mm1.7315 to 1.7320 in.
Undersize Bearing Code Number Marking
0.2 mm
0.008 in.
Crankshaft bearing 2 02 15694-23930
020 US
Crankshaft bearing 2F 02 1G460-07530
Crankshaft bearing 3 02 1G460-07580
020 US
Crankshaft bearing 3F 02 1G460-07630
0.4 mm
0.02 in.
Crankshaft bearing 2 04 15694-23940
040 US
Crankshaft bearing 2F 04 1G460-07540
Crankshaft bearing 3 04 1G460-07590
040 US
Crankshaft bearing 3F 04 1G460-07640
Undersize 0.2 mm0.008 in.
0.4 mm
0.02 in.
Dimension A 1.8 to 2.2 mm radius0.071 to 0.086 in. radius
1.8 to 2.2 mm radius
0.071 to 0.086 in. radius
*Dimension B 1.0 to 1.5 mm relief0.040 to 0.059 in. relief
1.0 to 1.5 mm relief
0.040 to 0.059 in. relief
Dimension C 43.734 to 43.750 mm dia.1.7219 to 1.7224 in. dia.
43.534 to 43.550 mm dia.
1.7140 to 1.7145 in. dia.
The crankshaft journal must be fine-finished to higher than Rmax = 0.8S
*Holes to be de-burred and edges rounded with 1.0 to 1.5 mm
(0.040 to 0.059 in.) relief.
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S65
(5) Cylinder
Cylinder Wear
1. Measure the I.D. of the cylinder at the six positions (see figure)
with a cylinder gauge to find the maximum and minimum I.D.'s.
2. Get the difference (Maximum wear) between the maximum and
the minimum I.D.'s.
9Y1210318ENS0120US0
Correcting Cylinder (Oversize)
1. When the cylinder is worn beyond the allowable limit, bore and
hone it to the specified dimension.
2. Replace the piston and piston rings with oversize ones.
Oversize : 0.5 mm (0.02 in.)
Marking : 05
NOTE
• When the oversize cylinder is worn beyond the allowable
limit, replace the cylinder block with a new one.
9Y1210318ENS0121US0
Cylinder I.D.
Factory spec. 74.500 to 74.519 mm2.9331 to 2.9338 in.
Allowable limit 74.669 mm2.9397 in.
(A) Top
(B) Middle
(C) Bottom (Skirt)
(a) Right-Angled to Piston Pin
(b) Piston Pin Direction
Cylinder liner I.D.
Factory spec. 75.000 to 75.019 mm2.9528 to 2.9535 in.
Allowable limit 75.150 mm2.9587 in.
Finishing Hone to 2.2 to 3.0 µmRz(0.000087 to 0.00011 in.Rz)
(1) Cylinder I.D. (Before Correction) (2) Cylinder I.D. (Oversize)
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S66
(6) Oil Pump
Rotor Lobe Clearance
1. Measure the clearance between lobes of the inner rotor and the
outer rotor with a thickness gauge.
2. If the clearance exceeds the factory specifications, replace the
oil pump rotor assembly.
9Y1210318ENS0122US0
Clearance between Outer Rotor and Pump Body
1. Measure the clearance between the outer rotor and the pump
body with a thickness gauge.
2. If the clearance exceeds the factory specifications, replace the
oil pump rotor assembly.
9Y1210318ENS0123US0
Clearance between Rotor and Cover
1. Put a strip of plastigage onto the rotor face with grease.
2. Install the cover and tighten the screws.
3. Remove the cover carefully, and measure the amount of the
flattening with the scale and get the clearance.
4. If the clearance exceeds the factory specifications, replace oil
pump rotor assembly.
9Y1210318ENS0124US0
Rotor lobe clearance Factory spec. 0.030 to 0.14 mm0.0012 to 0.0055 in.
Clearance between outer
rotor and pump body Factory spec.
0.070 to 0.15 mm
0.0028 to 0.0059 in.
Clearance between rotor
and cover Factory spec.
0.0750 to 0.135 mm
0.00296 to 0.00531 in.
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S67
(7) Starter
Overrunning Clutch
1. Inspect the pinion for wear or damage.
2. If there is any defect, replace the overrunning clutch assembly.
3. Check that the pinion turns freely and smoothly in the
overrunning direction and does not slip in the cranking direction.
4. If the pinion slips or does not rotate in the both directions,
replace the overrunning clutch assembly.
9Y1210318ENS0125US0
Commutator and Mica
1. Check the contact face of the commutator for wear, and grind
the commutator with emery paper if it is slightly worn.
2. Measure the commutator O.D. with an outside micrometer at
several points.
3. If the minimum O.D. is less than the allowable limit, replace the
armature.
4. If the difference of the O.D.'s exceeds the allowable limit, correct
the commutator on a lathe to the factory specification.
5. Measure the mica undercut.
6. If the undercut is less than the allowable limit, correct if with a
saw blade and chamfer the segment edges.
9Y1210318ENS0126US0
Brush Wear
1. If the contact face of the brush is dirty or dusty, clean it with
emery paper.
2. Measure the brush length (A) with vernier calipers.
3. If the length is less than the allowable limit, replace the yoke
assembly and brush holder.
9Y1210318ENS0127US0
Commutator O.D.
Factory spec. 28.0 mm1.10 in.
Allowable limit 27.0 mm1.06 in.
Difference of O.D.'s
Factory spec.
Less than
0.05 mm
0.002 in.
Allowable limit 0.4 mm0.02 in.
Mica under cut
Factory spec. 0.45 to 0.75 mm0.018 to 0.029 in.
Allowable limit 0.2 mm0.008 in.
(1) Segment
(2) Undercut
(3) Mica
(a) Good
(b) Bad
Brush length (A)
Factory spec. 14.0 mm0.551 in.
Allowable limit 11.1 mm0.437 in.
(A) Brush Length
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S68
Brush Holder
1. Check the continuity across the brush holder and the holder
support with an ohmmeter.
2. If it conducts, replace the brush holder.
9Y1210318ENS0128US0
Armature Coil
1. Check the continuity across the commutator and armature coil
core with an ohmmeter.
2. If it conducts, replace the armature.
3. Check the continuity across the segments of the commutator
with an ohmmeter.
4. If it does not conduct, replace the armature.
9Y1210318ENS0129US0
Field Coil
1. Check the continuity across the lead (1) and brush (2) with an
ohmmeter.
2. If it does not conduct, replace the yoke assembly.
3. Check the continuity across the brush (2) and yoke (3) with an
ohmmeter.
4. If it conducts, replace the yoke assembly.
9Y1210318ENS0130US0
(1) Lead
(2) Brush
(3) Yoke
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S69
(8) Alternator
Bearing
1. Check the bearing for smooth rotation.
2. If it does not rotate smoothly, replace it.
9Y1210318ENS0131US0
Stator
1. Measure the resistance across each lead of the stator coil with
resistance range of circuit tester.
2. If the measurement is not within factory specification, replace it.
3. Check the continuity across each stator coil lead and core with
resistance range of circuit tester.
4. If infinity is not indicated, replace it.
9Y1210318ENS0132US0
Rotor
1. Measure the resistance across the slip rings.
2. If the resistance is not the factory specification, replace it.
3. Check the continuity across the slip ring and core with
resistance range of circuit tester.
4. If infinity is not indicated, replace it.
9Y1210318ENS0133US0
Slip Ring
1. Check the slip ring for score.
2. If scored, correct with an emery paper or on a lathe.
3. Measure the O.D. of slip ring with vernier calipers.
4. If the measurement is less than the allowable limit, replace it.
9Y1210318ENS0134US0
Brush Wear
1. Measure the brush length with vernier calipers.
2. If the measurement is less than allowable limit, replace it.
3. Make sure that the brush moves smoothly.
4. If the brush is defective, replace it.
9Y1210318ENS0135US0
Resistance Factory spec. Less than 1.0 Ω
Resistance Factory spec. 2.9 Ω
Slip ring O.D.
Factory spec. 14.4 mm0.567 in.
Allowable limit 14.0 mm0.551 in.
Brush length
Factory spec. 10.5 mm0.413 in.
Allowable limit 8.4 mm0.33 in.
KiSC issued 06, 2009 A
ENGINEWG972-E2,DF972-E2,DG972-E2, WSM
1-S70
Rectifier
1. Check the continuity across each diode of rectifier with
resistance range of circuit tester.
2. The rectifier is normal if the diode in the rectifier conducts in one
direction and does not conduct in the reverse direction.
9Y1210318ENS0136US0
IC Regulator
1. Check the continuity across the B terminal (2) and the F
terminal (1) of IC regulator with resistance range of circuit tester.
2. The IC regulator is normal if the conducts in one direction and
does not conduct in the reverse direction.
9Y1210318ENS0137US0
(1) F Terminal (2) B Terminal
KiSC issued 06, 2009 A
EDITOR:
KUBOTA FARM & INDUSTRIAL MACHINERY SERVICE, LTD.
64, ISHIZU-KITAMACHI, SAKAI-KU, SAKAI-CITY, OSAKA, 590-0823, JAPAN
PHONE : (81)72-241-1129
FAX : (81)72-245-2484
E-mail : ksos-pub@kubota.co.jp
KUBOTA Corporation
Printed in Japan 2009. 06, S, EI, E I , e Code No.9Y111-03180
2009. 02, S, EI, E I , e

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