Kubota WG 972-E2, DF 972-E2, DG 972-E2 Engine Workshop Manual
WG 972-E2, DF 972-E2, DG 972-E2 are Kubota's gasoline, gasoline/LPG, and natural gas engines, respectively. These engines are designed for general power source applications. The manual covers information on the engine's mechanism, servicing, and maintenance.
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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
INFORMATION
CONTENTS
[4] KUBOTA RECOMMENDED LPG FUEL SPECIFICATIONS (DF972-E2)................................ I-6
[7] KUBOTA RECOMMENDED FUEL SPECIFICATIONS (DG972-E2) ....................................... I-7
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
1. SAFETY FIRST
INFORMATION
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.
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.
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KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
I-2
INFORMATION
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.
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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.
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KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
INFORMATION
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.
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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.
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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.
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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.
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WG972-E2,DF972-E2,DG972-E2, WSM
2. SPECIFICATIONS
INFORMATION
Number of Cylinder
Type
Bore × Stroke
Total Displacement
ISO Net Continuous
Model
ISO / SAE Net Intermittent
SAE Gross Intermittent
WG972-E2
Vertical, water cooled, 4-cycle
Gasoline engine
Maximum Bare Speed
Minimum Bare Idling Speed
Cylinder Head
Ignition System
Governor
Direction of Rotation
Spark Plug
Ignition Timing
Firing Order
Compression Ratio
Lubricating System
Oil Pressure Indication
Lubricating Filter
Cooling System
Starting System
Starting Motor
Battery
Charging Alternator
Fuel
Lubricating Oil
Lubricating Oil Capacity
Weight (Dry)
Application
*The specification described above is of the standard engine of each model.
*Conversion Formula : HP = 0.746 kW, PS = 0.7355 kW
DF972-E2
3
Vertical, water cooled, 4-cycle Dual Fuel (Gasoline / LPG) engine
Gasoline fuel LPG fuel
74.5 x 73.6 mm (2.93 x 2.90 in.)
962 cm
3
(58.7 cu.in.)
18.6 kW / 3600 min
-1
(rpm)
25.0 HP / 3600 min
-1
(rpm)
23.1 kW / 3600 min
-1
(rpm)
31.0 HP / 3600 min
-1
(rpm)
24.2 kW / 3600 min
-1
(rpm)
32.5 HP / 3600 min
-1
(rpm)
3850 to 3950 min
-1
(rpm)
1400 to 1600 min
-1
(rpm)
Overhead-Valve
Distributor-Less Solid Stage Type
17.5 kW / 3600 min
23.5 HP / 3600 min
22.0 kW / 3600 min
29.5 HP / 3600 min
23.1 kW / 3600 min
31.0 HP / 3600 min
Centrifugal Ball Mechanical Type / Electronic Governor
Counter-Clockwise (Viewed from flywheel)
NGK BKR4E
0.37 rad (21 °) before T.D.C. / 3600 min
-1
(rpm)
-1
-1
-1
-1
-1
-1
(rpm)
(rpm)
(rpm)
(rpm)
(rpm)
(rpm)
1-2-3
9.2 : 1
Forced Lubrication by Trochoid Pump
Electrical Type Switch
Full Flow Paper Filter (Cartridge Type)
Pressurized Radiator (not included in the basic model), Forced Circulation with Water Pump
Electric Starting with Starter
12V, 1.0 kW
12 V, 52 AH or equivalent
12 V, 150 W
*Unleaded Automobile Gasoline
Better than SH Class (API)
3.4 L (0.90 U.S.gals)
72.0 kg (159 lbf)
General Power Source
Standard Commercial LP Gas
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KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
INFORMATION
Number of Cylinder
Type
Bore × Stroke
Total Displacement
ISO Net Continuous
Model
ISO / SAE Net Intermittent
SAE Gross Intermittent
Maximum Bare Speed
Minimum Bare Idling Speed
Cylinder Head
Ignition System
Governor
Direction of Rotation
Spark Plug
Ignition Timing
Firing Order
Compression Ratio
Lubricating System
Oil Pressure Indication
Lubricating Filter
Cooling System
Starting System
Starting Motor
Battery
Charging Alternator
Fuel
Lubricating Oil
Lubricating Oil Capacity
Weight (Dry)
Application
DG972-E2-BBH DG972-E2-SAEH
3
Vertical, water cooled, 4-cycle Natural Gas engine
74.5 x 73.6 mm (2.93 x 2.90 in.)
962 cm
3
(58.7 cu.in.)
14.5 kW / 3600 min
-1
(rpm)
19.4 HP / 3600 min
-1
(rpm)
17.6 kW / 3600 min
-1
(rpm)
23.6 HP / 3600 min
-1
(rpm)
18.7 kW / 3600 min
-1
(rpm)
25.1 HP / 3600 min
-1
(rpm)
3850 to 3950 min
-1
(rpm)
1400 to 1600 min
-1
(rpm)
Overhead-Valve
Distributor-Less Solid Stage Type
Centrifugal Ball Mechanical Type / Electronic Governor
Counter-Clockwise (Viewed from flywheel)
NGK BKR4E
0.49 rad (28 °) before T.D.C. / 3600 min
-1
(rpm)
*The specification described above is of the standard engine of each model.
*Conversion Formula : HP = 0.746 kW, PS = 0.7355 kW
1-2-3
9.2 : 1
Forced Lubrication by Trochoid Pump
Electrical Type Switch
Full Flow Paper Filter (Cartridge Type)
Pressurized Radiator (not included in the basic model), Forced Circulation with Water Pump
Electric Starting with Starter
12V, 1.0 kW
72.0 kg (159 lbf)
12 V, 52 AH or equivalent
12 V, 480 W
Natural Gas
Better than SH Class (API)
3.4 L (0.90 U.S.gals)
General Power Source
95.4 kg (210 lbf)
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WG972-E2,DF972-E2,DG972-E2, WSM
INFORMATION
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.
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[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.
Part
Genuine air cleaner
Genuine inlet pipe
Part No.
1G657-1101-1
EG561-1164-1
Brake horse power SAE net int.
23.1 kP (31.0 HP) / 3600 min
-1
(rpm)
Allowable maximum exhaust back pressure
19.6 kPa (147 mmHg) / 3600 min
-1
(rpm)
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.
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[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.
Altitude Compensation Kit
Original Carburetor (with 0 m (0 ft) kit)
1000 m (3281 ft) compensation kit
2000 m (6562 ft) compensation kit
Applicable Altitude Ranges
0 to 700 m (0 to 2300 ft)
300 to 1700 m (984 to 5577 ft)
1300 to 2700 m (4265 to 8858 ft)
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[3] LPG REGULATOR WITH VAPORIZER (DF972-E2)
When operating DF972-E2 on LPG, only a KUBOTA GENUINE LPG REGULATOR KIT can be used.
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[4] KUBOTA RECOMMENDED LPG FUEL SPECIFICATIONS
(DF972-E2)
• Commercial Propane gas only.
• Equivalent to Propane H-D-5 of GPA* standards.
C
3
H
8
≥ 90 %
C
3
H
6
≤ 5 %
C
4
H
10
≤ 2.5 %
Others
−
*GPA means Gas Processors Association (U.S.A.)
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[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.
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KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
INFORMATION
[6] GAS REGULATOR (DG972-E2)
When operating DG972-E2 on natural gas, only a KUBOTA GENUINE GAS REGURATOR can be used.
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[7] KUBOTA RECOMMENDED FUEL SPECIFICATIONS (DG972-E2)
• Natural gas only.
• Consult KUBOTA for further information of fuel used.
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[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.
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WG972-E2,DF972-E2,DG972-E2, WSM
4. PERFORMANCE CURVES
WG972
INFORMATION
(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
DF972
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WG972-E2,DF972-E2,DG972-E2, WSM
DG972
INFORMATION
(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
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WG972-E2,DF972-E2,DG972-E2, WSM
5. DIMENSIONS
WG972, DF972
INFORMATION
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KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
WG972, DF972 (Electronic Governor Model)
INFORMATION
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WG972-E2,DF972-E2,DG972-E2, WSM
DG972-E2-BBH
INFORMATION
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KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
DG972-E2-SAEH
INFORMATION
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KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
6. WIRING DIAGRAM
INFORMATION
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GENERAL
KiSC issued 06, 2009 A
GENERAL
CONTENTS
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
GENERAL
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
Alphabet or
Number
Year
Alphabet or
Number
Year
C
D
E
8
9
A
B
4
5
6
7
1
2
3
2008
2009
2010
2011
2012
2013
2014
2001
2002
2003
2004
2005
2006
2007
N
P
R
S
T
V
J
K
L
M
F
G
H
2022
2023
2024
2025
2026
2027
2015
2016
2017
2018
2019
2020
2021
(1) Engine Model Name and Serial
Number
[A] WG972-E2
[B] DF972-E2
[C] DG972-E2
(To be continued)
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WG972-E2,DF972-E2,DG972-E2, WSM
(Continued)
GENERAL
Month of manufacture
Month
January
February
March
April
May
June
July
August
September
October
November
December
Engine Lot Number
A0001 ~ A9999 B0001 ~ BZ999
C0001 ~ C9999
E0001 ~ E9999
D0001 ~ DZ999
F0001 ~ FZ999
G0001 ~ G9999
J0001 ~ J9999
L0001 ~ L9999
N0001 ~ N9999
H0001 ~ HZ999
K0001 ~ KZ999
M0001 ~ MZ999
P0001 ~ PZ999
Q0001 ~ Q9999
S0001 ~ S9999
U0001 ~ U9999
W0001 ~ W9999
Y0001 ~ Y9999
R0001 ~ RZ999
T0001 ~ TZ999
V0001 ~ VZ999
X0001 ~ XZ999
Z0001 ~ ZZ999
e.g.
* Alphabetical letters "I" and "O" are not used.
(a)
• WG972
(b) (c)
- 8 B
(d)
A001
(a)
• DF972
(b) (c)
- 8 B
(d)
A001
(a)
• DG972
(b) (c)
- 8 B
(d)
A001
(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)
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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.
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WG972-E2,DF972-E2,DG972-E2, WSM
GENERAL
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.
(1) Tamper Resistance
[A] Carburetor
[B] Pick-up Sensor
[C] Vaporizer
[D] Regulator
[E] Governor Lever
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WG972-E2,DF972-E2,DG972-E2, WSM
[2] CYLINDER NUMBER
GENERAL
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.
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WG972-E2,DF972-E2,DG972-E2, WSM
GENERAL
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.
(1) Grease
(2) Force
(3) Place the Sharp Edge the Direction of Force
(A) External Snap Ring
(B) Internal Snap Ring
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KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
GENERAL
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]
Service Interval
Item
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.)
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.
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KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
[DG972-E2]
Item
Daily
Every 50 hrs
Every 100 hrs
Service Interval
Every 200 hrs
Every 1 year
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.)
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.
GENERAL
Every 1000 hrs
Every 2 years
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GENERAL
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.
(1) Dipstick
9Y1210318GEG0010US0
G-8
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
GENERAL
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..
(1) Radiator Cap
(2) Recovery Tank
(1) Dust Cap
(2) Element
A : FULL
B : LOW
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.
(3) "TOP" Mark
9Y1210318GEG0012US0
G-9
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
GENERAL
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.
Above 25 °C (77 °F)
0 °C to 25 °C (32 °F to 77 °F)
Below 0 °C (32 °F)
SAE30 or SAE10W-30
SAE20 or SAE10W-30
SAE10W or SAE10W-30
Engine oil capacity
Tightening torque
(1) Drain Plug
Drain plug
3.4 L
0.90 U.S.gals
33 to 37 N·m
3.3 to 3.8 kgf·m
24 to 27 lbf·ft
(2) Dipstick
9Y1210318GEG0017US0
G-10
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
GENERAL
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.
(1) Engine Oil Filter Cartridge
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/cm
2
,
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.
(1) Clamp (2) Fuel Hose
9Y1210318GEG0021US0
G-11
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
GENERAL
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
G-12
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
GENERAL
[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.
Spark plug gap Factory spec.
0.60 to 0.70 mm
0.024 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
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.
Deflection (A) Factory spec.
7.0 to 9.0 mm
0.28 to 0.35 in.
(A) Deflection
9Y1210318GEG0001US0
G-13
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
GENERAL
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.
(A) Good (B) Bad
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.
Above 25 °C (77 °F)
0 °C to 25 °C (32 °F to 77 °F)
Below 0 °C (32 °F)
SAE30 or SAE10W-30
SAE20 or SAE10W-30
SAE10W or SAE10W-30
Engine oil capacity
Tightening torque
(1) Drain Plug
Drain plug
3.4 L
0.90 U.S.gals
33 to 37 N·m
3.3 to 3.8 kgf·m
24 to 27 lbf·ft
(2) Dipstick
9Y1210318GEG0029US0
G-14
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
GENERAL
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.
(1) Engine Oil Filter Cartridge
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.
(1) Upper Hose (2) Lower Hose
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.
(1) 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).
(1) Fuel Filter
(2) Fuel Hose
(3) Clamp
9Y1210318GEG0035US0
G-15
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
GENERAL
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.
Cleaning Carburetor (WG972-E2, DF972-E2)
9Y1210318GEG0037US0
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
G-16
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
GENERAL
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.
(1) Radiator Cap
(2) Drain Plug
(3) Drain Cock
(4) Recovery Tank
A : FULL
B : LOW
9Y1210318GEG0040US0
G-17
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
GENERAL
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 %.
Vol % anti-freeze
40
50
Freezing point
°C
−24
−37
°F
−11
−35
Boiling point*
°C
106
108
°F
223
226
* 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.
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
9Y1210318GEG0042US0
G-18
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
GENERAL
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.
(1) Coolant Hoses to Vaporizer
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.
(1) Vacuum Lock Hoses
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.
(1) Vaporizer
(2) Coolant Hose
(3) Wrench
(4) Drain Plug
(5) Liquid Gasket
(6) Joint
9Y1210318GEG0045US0
G-19
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
GENERAL
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.
Adjustable Cylinder Location of Piston
Valve Arrangement
Intake valve Exhaust valve
No. 1
No. 2
No. 3
: When No. 1 piston is at the compression top dead center position.
: When No. 1 piston is at the overlap position.
Intake and exhaust valve clearance (cold)
Factory spec.
0.145 to 0.185 mm
0.00571 to 0.00728 in.
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.
(1) "1TC" Mark
(2) Alignment Mark
A : Gear Case Side
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
G-20
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
GENERAL
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.
Valve seat width Factory spec.
2.12 mm
0.0835 in.
(1) Correct
(2) Incorrect
(3) Incorrect
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).
(1) Coolant Hose
(2) Coolant Hose
(3) Vaporizer
A : Joint
9Y1210318GEG0052US0
G-21
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
GENERAL
Replacing Vacuum Lock Hose of LPG Vaporizer (DF972-E2)
1. Connect the new vacuum lock hose (1).
(1) Vacuum Lock Hose
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.
Pressure Factory spec.
30 to 34 kPa
0.30 to 0.35 kgf/cm
2
4.3 to 4.9 psi
(1) Plug (2) Pressure Gauge
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/cm
2
,
1.4 psi).
3. Make sure that there is no air leak.
4. If there is a leakage, replace the vaporizer.
(1) Vapor Hose
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.
(1) Vacuum Lock Hose (2) Joint
9Y1210318GEG0056US0
G-22
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
GENERAL
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.
(1) Upper Hose (2) Lower Hose
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
G-23
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
GENERAL
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.
(1) Radiator Cap
(2) Drain Plug
(3) Recovery Tank
A : Full
B : Low
(To be continued)
G-24
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
(Continued)
GENERAL
(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 %.
Vol % anti-freeze
40
50
°C
Freezing point
°F
−24
−37
−11
−35
°C
Boiling point*
°F
106
108
223
226
* 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
G-25
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
5. SPECIAL TOOLS
Timing Light
Application
• Use to adjust the ignition timing.
GENERAL
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.
(1) Gauge
(2) Cable
(3) Threaded Joint
(4) Adaptor 1
(5) Adaptor 2
(6) Adaptor 3
(7) Adaptor 4
(8) Adaptor 5
WSM000001GEG0015US0
Pressure Gauge
Specification
• 98 kPa (1.0 kgf/cm
2
, 14 psi)
Application
• Check the pressure of vaporizer.
WSM000001GEG0090US0
G-26
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
GENERAL
Valve Guide Replacing Tool
Application
• Use to press out and press fit the valve guide.
G
H
I
J
C
D
A
B
E
F
K
L
C1
C2
C0.3
200 mm (7.87 in.)
80 mm (3.1 in.)
40 mm (1.6 in.)
20 mm dia. (0.79 in. dia.)
9.960 to 9.980 mm dia. (0.3922 to 0.3929 in. dia.)
5.50 to 5.70 mm dia. (0.217 to 0.224 in. dia.)
15 mm (0.59 in.)
6.00 to 6.10 mm dia. (0.237 to 0.240 in. dia.)
5 mm (0.2 in.)
18 mm dia. (0.71 in. dia.)
10.6 to 10.7 mm dia. (0.418 to 0.421 in. dia.)
7 mm (0.3 in.)
Chamfer 1.0 mm (0.039 in.)
Chamfer 2.0 mm (0.079 in.)
Chamfer 0.3 mm (0.01 in.)
9Y1210318GEG0060US0
Bushing Replacing Tool
Application
• Use to press out and to press fit the bushing.
[For small end bushing]
A
145 mm (5.71 in.)
D
E
B
C
F a b
20 mm (0.79 in.)
100 mm (3.94 in.)
19.90 to 19.95 mm (0.7835 to 0.7854 in.)
21.90 to 21.95 mm dia. (0.8622 to 0.8641 in. dia.)
25 mm (0.98 in.)
6.3 µm (250 µin.)
6.3 µm (250 µin.)
[For idle gear bushing]
A
150 mm (5.91 in.)
D
E
B
C
F a b
20 mm (0.79 in.)
100 mm (3.94 in.)
19.90 to 19.95 mm (0.7835 to 0.7854 in.)
21.90 to 21.95 mm dia. (0.8622 to 0.8641 in. dia.)
25 mm (0.98 in.)
6.3 µm (250 µin.)
6.3 µm (250 µin.)
9Y1210318GEG0061US0
G-27
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
GENERAL
Flywheel Stopper
Application
• Use to loosen and tighten the flywheel screw.
C
D
A
B
E
F
20 mm (0.79 in.)
15 mm (0.59 in.)
10 mm dia. (0.39 in. dia.)
30 mm (1.2 in.)
8 mm (0.3 in.)
200 mm (7.87 in.)
9Y1210318GEG0062US0
Crankshaft Bearing 1 Replacing Tool
Application
• Use to press out and press fit the crankshaft bearing 1.
[Press Out]
A
135 mm (5.31 in.)
E
F
G
H
B
C
D
72 mm (2.8 in.)
40 mm radius (1.6 in. radius)
10 mm (0.39 in.)
22 mm (0.87 in.)
20 mm dia. (0.79 in. dia.)
47.90 to 47.95 mm dia. (1.886 to 1.887 in. dia.)
43.90 to 43.95 mm dia. (1.729 to 1.730 in. dia.)
[Press Fit]
A
130 mm (5.12 in.)
E
F
G
H
B
C
D
72 mm (2.8 in.)
40 mm radius (1.6 in. radius)
9 mm (0.4 in.)
24 mm (0.94 in.)
20 mm (0.79 in.)
68 mm dia. (2.7 in. dia.)
43.90 to 43.95 mm dia. (1.729 to 1.730 in. dia.)
9Y1210318GEG0063US0
G-28
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
GENERAL
Valve Stem Seal Replacing Tool
Application
• Use to press fit the valve stem seal.
K
L
M a b c
G
H
I
J
C
D
A
B
E
F
17.5 mm dia. (0.689 in. dia.)
13.7 to 13.9 mm dia. (0.540 to 0.547 in. dia.)
11.0 to 11.2 mm dia. (0.433 to 0.440 in. dia.)
75 mm (3.0 in.)
60 mm (2.4 in.)
45 mm (1.8 in.)
11.5 to 11.6 mm (0.453 to 0.456 in.)
8.5 mm (0.33 in.)
37.5 mm (1.48 in.)
6 mm dia. (0.2 in. dia.)
6 mm dia. (0.2 in. dia.)
R 30
26 mm dia. (1.0 in. dia.)
Chamfer 0.3 mm (0.01 in.)
Chamfer 0.4 mm (0.02 in.)
Chamfer 0.2 mm (0.008 in.)
9Y1210318GEG0064US0
G-29
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
GENERAL
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.
(1) Connectivity Kit
A : To Actuator
B : From Engine Control Harness
C : To Personal Computer
9Y1210318GEG0065US0
G-30
KiSC issued 06, 2009 A
1
ENGINE
KiSC issued 06, 2009 A
MECHANISM
CONTENTS
[8] ELECTRO MAGNETIC FUEL FEED PUMP (FOR GASOLINE LINE) ............................... 1-M22
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
1. ENGINE BODY
[1] CYLINDER BLOCK
ENGINE
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.
(1) Cylinder Head Cover (2) Rubber Packing
9Y1210318ENM0002US0
1-M1
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
[3] CYLINDER HEAD
[4] CRANKSHAFT
ENGINE
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.
(1) Intake Port (2) Exhaust Port
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.
(1) Valve
(2) Valve Seat
(3) Main Combustion Chamber
(4) Piston
(5) Spark Plug
9Y1210318ENM0004US0
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).
(1) Crankshaft Bearing 1
(2) Crankshaft
(3) Feather Key
(4) Crankshaft Bearing 3
(5) Thrust Bearing
(6) Crankshaft Bearing 2
9Y1210318ENM0005US0
1-M2
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
[5] PISTON AND PISTON RING
ENGINE
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.
(1) Combustion Chamber
(2) Top Ring
(3) Second Ring
(4) Oil Ring
(5) Strut
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.
(1) Molybdenum Disulfide
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.
(1) Gear Case
(2) Oil Pan
(3) Crank Case
9Y1210318ENM0008US0
1-M3
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
[7] CONNECTING ROD
ENGINE
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).
(1) Small End Bushing
(2) Connecting Rod
(3) Crankpin Bearing
(4) Connecting Rod Cap
(5) Connecting Rod Screw
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.
(1) Camshaft
(2) Feather Key
(3) Camshaft Stopper
(4) Cam Gear
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).
(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
9Y1210318ENM0011US0
1-M4
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
[10] ROCKER ARM ASSEMBLY
ENGINE
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.
(1) Adjusting Screw
(2) Rocker Arm
(3) Rocker Arm Shaft
(4) Rocker Arm Bracket
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.
(1) Valve Cap
(2) Collet
(3) Spring Retainer
(4) Spring
(5) Stem Seal
(6) Valve Guide
(7) Inlet Valve
(8) Exhaust Valve
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.
(1) Crankshaft
(2) Flywheel
(3) Flywheel Mounting Screw
9Y1210318ENM0014US0
1-M5
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
[13] CLOSED BREATHER
ENGINE
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).
(1) Breather Hose
(2) Air Cleaner Flange
(3) Breather Assembly
(a) Blow-by Gas
(b) Intake Air
9Y1210318ENM0015US0
1-M6
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
2. LUBRICATING SYSTEM
[1] GENERAL
ENGINE
(A) Piston
(B) Rocker Arm and Rocker
Arm Shaft
(C) Camshaft
(D) Oil Filter Cartridge and
Relief Valve
(E) Oil Strainer (F) Oil Pump
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
1-M7
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
[2] OIL PUMP
[3] RELIEF VALVE
ENGINE
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.
(1) Inlet Port
(2) Inner Rotor
(3) Outlet Port
(4) Outer Rotor
9Y1210318ENM0017US0
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.
(1) Spring
(2) Ball
(3) Valve Seat
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/cm
2
, 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.
(1) Bypass Valve (2) Filter Element
9Y1210318ENM0019US0
1-M8
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
[5] OIL PRESSURE SWITCH
ENGINE
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.
(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/cm
2
, 7 psi) or less
9Y1210318ENM0020US0
1-M9
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
3. COOLING SYSTEM
[1] GENERAL
[2] COOLING FIN
ENGINE
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.
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
9Y1210318ENM0021US0
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.
(1) Cooling Fin
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).
(1) Bearing Unit
(2) Water Pump Body
(3) Mechanical Seal
(4) Impeller
9Y1210318ENM0023US0
1-M10
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
[4] THERMOSTAT
[5] RADIATOR
ENGINE
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.
(1) Seat
(2) Valve
(3) Pellet
(4) Spindle
(5) Synthetic Rubber(6)Wax
(Solid)
(7) Spring
(8) Wax (liquid)
9Y1210318ENM0024US0
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.
(1) Tube
(2) Fin
A : Cooling Air
9Y1210318ENM0025US0
1-M11
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
[6] RADIATOR CAP
ENGINE
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.
(1) Pressure Valve (Opening pressure 88 kPa
(0.90 kgf/cm
2
, 13 psi))
(2) Vacuum Valve
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.
(1) Vaporizer
(2) Hot Coolant In
(3) Hot Coolant Out
9Y1210318ENM0027US0
1-M12
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
4. FUEL SYSTEM
[1] GENERAL
(1) WG972-E2, DF972-E2
ENGINE
(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
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-M13
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
(2) DG972-E2
ENGINE
(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
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-M14
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
[2] CARBURETOR AND GAS MIXER
(1) Carburetor (WG972-E2)
ENGINE
(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
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-M15
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
(2) Carburetor (DF972-E2)
ENGINE
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.
(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
9Y1210318ENM0031US0
1-M16
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
(3) Gas Mixer (DG972-E2)
ENGINE
The gas mixer is equipment to mix the fuel supplied from the regulator with air and to send the mixture to the cylinder.
(1) Venturi
(2) Throttle Valve
(A) Air
(B) Natural Gas
(C) Mixture (Air / Natural Gas)
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.
(1) Secondary Chamber
(2) Water Passage
(3) Primary Chamber
(4) Vacuum Lock Chamber
9Y1210318ENM0033US0
1-M17
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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/cm
2
, 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.
(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
9Y1210318ENM0034US0
1-M18
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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.
(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
9Y1210318ENM0035US0
1-M19
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
[4] REGULATOR (DG972-E2)
ENGINE
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.
(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
9Y1210318ENM0036US0
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.
(A) OUT
(B) IN
(1) Diaphragm
(2) Balance Spring
(3) Balance Screw
(4) Tamper Cap
(5) Spring
(6) Lever
(7) Screw
(8) Valve
9Y1210318ENM0037US0
1-M20
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
[5] GOVERNOR
[6] INLET MANIFOLD
ENGINE
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.
(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
9Y1210318ENM0038US0
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.
(1) Intake Manifold
9Y1210318ENM0039US0
1-M21
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
[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).
Type of filter element
Material of filter element
Filter mesh
Accordion-pleated paper type
Cotton fiber
15 µm (0.00059 in.)
(1) Filter Element
A : Inlet
B : Outlet
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
1-M22
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
5. IGNITION SYSTEM
[1] DEGITAL IGNITION SYSTEM
ENGINE
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.
(1) Flywheel
(2) Rotor
(3) Ignitor
(4) Ignition Coil
(5) Spark Plug
(6) Pick-up Sensor
9Y1210318ENM0042US0
1-M23
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
6. ELECTRICAL SYSTEM
[1] STARTING SYSTEM
ENGINE
Starter
The starter is the electromagnetic drive type.
Type of motor
Nominal output
Nominal output
Nominal output
Direction of rotation
DC, Series-wound, Electromagnetic drive
12V
1.0 kW
30 seconds (Do not rotate continuously for longer periods.)
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
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.
(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
9Y1210318ENM0044US0
1-M24
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
[2] CHARGING SYSTEM
ENGINE
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
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.
Model
Part No.
Weight
Regulated voltage
Battery to be used
Charge indication lamp
Alternator to be used
RS5155
RP201-53710
Approx. 200 g
14 to 15 V
12 V, 28 AH
12 V, 3.4 W
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
9Y1210318ENM0047US0
1-M25
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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.
(1) Blue Lead Wire
(2) Black Lead Wire
(3) Blue Lead Wire
(4) Green Lead Wire
(5) Yellow Lead Wire
(6) Red Lead Wire
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
(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
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-M26
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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
1-M27
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
[3] SOLENOID
ENGINE
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).
(1) Gasoline Solenoid Valve
(2) Gasoline Main Jet
(3) LPG Solenoid Valve
(4) LPG Main Jet
[A] WG972-E2
[B] DF972-E2
9Y1210318ENM0054US0
1-M28
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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.
(1) Actuator
9Y1210318ENM0055US0
1-M29
KiSC issued 06, 2009 A
SERVICING
CONTENTS
[1] TIGHTENING TORQUES FOR SPECIAL USE SCREWS, BOLTS AND NUTS.................1-S13
[2] TIGHTENING TORQUES FOR GENERAL USE SCREWS, BOLTS AND NUTS...............1-S14
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
1. TROUBLESHOOTING
[1] FOR GENERAL
Symptom
Engine Will Not Turn
Over
Engine jammed
Probable Cause
Engine Turns Over
Slowly but Does Not
Start
Engine Turns Over at
Normal Speed but
Does Not Start
Battery discharged
Starter malfunctioning
Wires disconnected
Increased resistance of moving parts
Excessively high viscosity engine oil at low temperature
Compression leak
Improper valve clearance
Defective ignition coil
Defective spark plug
Rough Low-Speed
Running and Idling
Rough High-Speed
Running
Defective ignitor
Clogged air cleaner
Defective ignition coil
Defective spark plug
Defective ignitor
Incorrect governor adjustment
Improper valve clearance
Defective ignitor
Defective spark plug
Engine Speed Does
Not Increase
Deficient Output
Defective ignition coil
Incorrect governor adjustment
Incorrect governor adjustment
Defective ignitor
Clogged air cleaner
Improper intake or exhaust valve sealing
Incorrect governor adjustment
Excessive carbon in engine
Improper valve clearance
Piston ring and cylinder worn
Clogged air cleaner
ENGINE
Solution
Check engine to find the problem and repair it
Charge
Repair or replace
Reconnect
Repair or replace
Use specified engine oil
Check the compression pressure and repair
Adjust
Replace
Adjust spark plug gap or replace
Replace
Clean or replace
Replace
Adjust spark plug gap or replace
Replace
Adjust
Adjust
Replace
Adjust spark plug gap or replace
Replace
Adjust
Adjust
Replace
Clean or replace
Replace
Reference
Page
–
–
–
–
G-8
Adjust
Remove carbon
Adjust
Replace
Clean or replace
–
1-S1
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
Symptom
Engine Noise
Probable Cause
Improper valve clearance
Spark knock due to low-octane fuel or carbon
Solution
Adjust
Use higher-octane fuel and remove carbon
Retighten
ENGINE
Reference
Page
–
–
9Y1210318ENS0001US0
Rattles from loosely mounted external components
[2] FOR GASOLINE FUEL
Symptom Probable Cause
Engine Turns Over at
Normal Speed but
Does Not Start
No fuel
Defective fuel system
Over choked
Flooding from carburetor
Rough Low-Speed
Running and Idling
Engine Speed Does
Not Increase
Incorrect carburetor idle adjustment
Incorrect carburetor adjustment
[3] FOR LPG FUEL
Symptom
Engine Turns Over at
Normal Speed but
Does Not Start
No LPG fuel
Probable Cause
Rough Low-Speed
Running and Idling
Defective vacuum lock system
Defective throttle lever position
Shortage of gas supply
Defective idling
Defection Output
LPG density is rich
Shortage LPG
Solution
Replenish fuel
Check fuel line and carburetor and repair
Clean spark plug
Check carburetor and repair / replace
Adjust
Reference
Page
–
–
–
–
Adjust
9Y1210318ENS0002US0
Solution
Reference
Page
– Replenish LPG fuel
Check LPG tank valve
Check shut off solenoid valve
Check vacuum hose
Replace vaporizer
Set throttle lever to the low idle position
Replenish LPG fuel
Check shut off solenoid valve
Replace vaporizer
Draining tar from vaporizer
Replace vaporizer
Repair or replace of fuel system
Replace vaporizer
–
–
–
9Y1210318ENS0003US0
1-S2
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
[4] FOR NATURAL GAS FUEL
Symptom Probable Cause
Engine Turns Over at
Normal Speed but
Does Not Start
No fuel
Defective fuel system
Rough Low-Speed
Running and Idling
Shortage of gas supply
Defective idling
Defection Output
Gas density is rich
Shortage gas
ENGINE
Solution
Reference
Page
– Check gas source
Check shut off solenoid valve
Check fuel system and repair
Check gas source
Check shut off solenoid valve
Replace regulator
Draining tar from regulator
Replace regulator
Repair or replace of fuel system
Replace regulator
–
–
–
–
–
9Y1210318ENS0004US0
1-S3
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
[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
ENGINE
(1) Refer to [Adjust Governor Lever of Electronic Governor]
1-S4
9Y1210318ENS0005US0
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
Engine does not start : Step 2
ENGINE
(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]
9Y1210318ENS0006US0
1-S5
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
Engine unstable
ENGINE
(1) Refer to the [Adjust Governor Lever of Electronic Governor]
9Y1210318ENS0007US0
1-S6
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
2. SERVICING SPECIFICATIONS
ENGINE BODY
Item Factory Specification
Valve Clearance (Cold)
Compression Pressure –
0.145 to 0.185 mm
0.00571 to 0.00728 in.
1.27 MPa
13.0 kgf/cm
185 psi
2
Variance Among
Cylinder
–
Top Clearance
Cylinder Head Surface Flatness
1.35 to 1.65 mm
0.0532 to 0.0649 in.
–
Valve Recessing (Intake and Exhaust)
Valve Stem to Valve Guide
• Valve Stem
• Valve Guide
Valve Face
Valve Seat
Valve Timing (Intake Valve)
Valve Timing (Exhaust Valve)
Valve Spring
Clearance
O.D.
I.D.
Angle
Angle
Width
Open
Close
Open
Close
Free Length
Tilt
−0.10 to 0.10 mm
−0.0039 to 0.0039 in.
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.
0.79 rad
45 °
0.79 rad
45 °
2.12 mm
0.0835 in.
0.35 rad
20 ° before T.D.C.
0.79 rad
45 ° after B.D.C.
0.87 rad
50 ° before B.D.C.
0.26 rad
15 ° after T.D.C.
31.3 to 31.8 mm
1.24 to 1.25 in.
–
Setting Load /
Setting Length
1-S7
65 N / 27.0 mm
6.6 kgf / 27.0 mm
15 lbf / 1.06 in.
Allowable Limit
–
0.88 MPa
9.0 kgf/cm
2
130 psi
10 % or less
–
0.05 mm
0.002 in.
0.30 mm
0.012 in.
0.10 mm
0.0039 in.
–
–
–
–
–
–
–
–
–
ENGINE
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
WG972-E2,DF972-E2,DG972-E2, WSM
Item
Rocker Arm Shaft to Rocker Arm
• Rocker Arm Shaft
• Rocker Arm
Push Rod
Tappet to Tappet Guide Bore
• Tappet
• Tappet Guide Bore
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
Idle Gear
Camshaft
Camshaft Journal to Cylinder Block Bore
• Camshaft Journal
• Cylinder Block Bore
Idle Gear Shaft to Idle Gear Bushing
• Idle Gear Shaft
• Idle Gear Bushing
Oil Clearance
O.D.
I.D.
Alignment
Oil Clearance
O.D.
I.D.
Backlash
Backlash
Backlash
Backlash
Side Clearance
Side Clearance
Alignment
Cam Height (Intake and Exhaust)
Oil Clearance
O.D.
I.D.
Oil Clearance
O.D.
I.D.
1-S8
Factory Specification
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.
–
0.016 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.
0.0430 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.
0.20 to 0.51 mm
0.0079 to 0.020 in.
0.15 to 0.31 mm
0.0059 to 0.012 in.
–
26.88 mm
1.058 in.
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.
0.020 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.
ENGINE
Allowable Limit
0.15 mm
0.0059 in.
–
–
0.25 mm
0.0098 in.
0.10 mm
0.0039 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.
0.80 mm
0.031 in.
0.50 mm
0.020 in.
0.01 mm
0.0004 in.
26.83 mm
1.056 in.
0.15 mm
0.0059 in.
–
–
0.10 mm
0.0039 in.
–
–
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
Piston Pin Bore
• Small End Bushing
Piston Pin to Small End Bushing
(Spare Parts)
• Small End Bushing
Piston Ring Gap
Item
Piston Pin to Small End Bushing
• Piston Pin
Piston Ring to Piston Ring Groove
Connecting Rod
Crankshaft
Crankpin to Crankpin Bearing
• Crankpin
• Crankpin Bearing
Crankshaft Journal to Crankshaft Bearing 1
• Crankshaft Journal
• Crankshaft Bearing 1
I.D.
Oil Clearance
O.D.
I.D.
Oil Clearance
I.D.
Top Ring
Second Ring
Oil Ring
(Upper and lower rail)
Top Ring
(Clearance)
Second Ring
(Clearance)
Oil Ring
(Clearance)
Alignment
Side Clearance
Alignment
Oil Clearance
O.D.
I.D.
Oil Clearance
O.D.
I.D.
Factory Specification
20.000 to 20.013 mm
0.78741 to 0.78791 in.
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.
0.013 to 0.075 mm
0.00052 to 0.0029 in.
20.026 to 20.077 mm
0.78843 to 0.79043 in.
0.15 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.
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 to 0.31 mm
0.0059 to 0.012 in.
–
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.
0.0340 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.
1-S9
ENGINE
Allowable Limit
20.05 mm
0.7894 in.
0.10 mm
0.0039 in.
–
–
0.20 mm
0.0079 in.
–
–
KiSC issued 06, 2009 A
–
0.15 mm
0.0059 in.
–
1.25 mm
0.0492 in.
1.25 mm
0.0492 in.
1.25 mm
0.0492 in.
0.15 mm
0.0059 in.
0.15 mm
0.0059 in.
0.20 mm
0.0079 in.
0.05 mm
0.002 in.
0.50 mm
0.020 in.
0.02 mm
0.0008 in.
0.15 mm
0.0059 in.
–
WG972-E2,DF972-E2,DG972-E2, WSM
Item
Crankshaft Journal to Crankshaft Bearing 2
(Flywheel Side)
Oil Clearance
• Crankshaft Journal O.D.
• Crankshaft Bearing 2 I.D.
Crankshaft Journal to Crankshaft Bearing 3
(Intermediate)
Oil Clearance
• Crankshaft Journal
O.D.
• Crankshaft Bearing 3
Cylinder Liner
[Standard]
Cylinder Liner
[Oversize : 0.5 mm (0.02 in.)]
I.D.
I.D.
I.D.
Factory Specification
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.
0.028 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.
74.500 to 74.519 mm
2.9331 to 2.9338 in.
75.000 to 75.019 mm
2.9528 to 2.9535 in.
ENGINE
Allowable Limit
0.20 mm
0.0079 in.
–
–
0.20 mm
0.0079 in.
–
–
74.669 mm
2.9397 in.
75.150 mm
2.9587 in.
1-S10
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
LUBRICATING SYSTEM
Item
Engine Oil Pressure
Inner Rotor to Outer Rotor
Outer Rotor to Pump Body
Inner Rotor to Cover
COOLING SYSTEM
Fan Belt
Thermostat
Radiator Cap
Item
Radiator
IGNITION SYSTEM
Spark Plug (NGK : BKR4E)
Item
Resistance of Ignition Coil
Pick-up Sensor
At Idle Speed
At Rated Speed
Clearance
Clearance
Clearance
ENGINE
Factory Specification
More than 50 kPa
0.5 kgf/cm
2
7 psi
200 to 440 kPa
2.0 to 4.5 kgf/cm
2
29 to 64 psi
0.030 to 0.14 mm
0.0012 to 0.0055 in.
0.070 to 0.15 mm
0.0028 to 0.0059 in.
0.0750 to 0.135 mm
0.00296 to 0.00531 in.
Allowable Limit
–
150 kPa
1.5 kgf/cm
2
21 psi
–
–
–
Tension
Factory Specification
7.0 to 9.0 mm / 98 N
0.28 to 0.35 in. / 98 N
(10 kgf, 22 lbf)
69.5 to 72.5 °C
157.1 to 162.5 °F
Allowable Limit
–
– Valve Opening
Temperature
(At Beginning)
Valve Opening
Temperature
(Opened
Completely)
Pressure Falling
Time
85 °C
185 °F
–
Weak Leakage
Test Pressure
More than 10 seconds for pressure fall from
90 → 60 kPa
0.9 → 0.6 kgf/cm
2
10 → 9 psi
No leak at specified pressure
–
–
Plug Gap
Primary (+) - (−)
Factory Specification
0.60 to 0.70 mm
0.024 to 0.027 in.
1.87 to 2.53 Ω at 20 °C
Secondary Side
(Primary (+) - Plug
Cap)
Resistance
10.4 to 15.6 kΩ at 20 °C
1.85 to 2.45 kΩ at 20 °C
Allowable Limit
–
–
–
–
1-S11
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ELECTRICAL SYSTEM
Starter
Alternator
Regulator
Fuel Cut Off Solenoid
Item
ELECTRONIC GOVERNOR
Item
Engine Speed Sensor to Ring Gear
(for Kubota original parts)
ENGINE
Commutator
(O.D.)
Difference
(O.D.)
Mica
(Undercut)
Brush
(Length)
No-load Voltage
Stator
(Resistance)
Rotor
(Resistance)
Slip Ring
(O.D.)
Brush
(Length)
Regulating Voltage
For Gasoline
(Resistance)
For LPG
(Resistance)
Factory Specification
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.
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.
14.2 to 14.8 V
38 Ω at 20 °C
28 Ω at 20 °C
Allowable Limit
27.0 mm
1.06 in.
0.4 mm
0.02 in.
0.2 mm
0.008 in.
11.1 mm
0.437 in.
–
–
–
14.0 mm
0.551 in.
8.4 mm
0.33 in.
–
–
–
Air Gap
Resistance
Factory Specification
0.80 to 1.2 mm
0.031 to 0.047 in.
Approx. 2.15 kΩ
Allowable Limit
–
–
9Y1210318ENS0008US0
1-S12
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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.
Item
*Cylinder head cover screw
*Rocker arm bracket screw
*Cylinder head screw
*Fan drive pulley screw
*Idle gear shaft mounting screw
*Connecting rod screw
*Flywheel screw
Bearing case cover mounting screw
*Main bearing case screw 2
*Main bearing case screw 1
Oil pressure switch
Spark plug
Drain plug
Carburetor mounting nut
Gas mixer mounting nut
Joint for LPG hose of vaporizer
(local arrangement)
Joint for vapor hose of vaporizer
Joint for coolant hose of vaporizer
Actuator mounting screw
Actuator flange screw
Governor lever nut
Starter's terminal B mounting nut
Dynamo's pulley nut
Alternator's pulley nut
Gasoline solenoid
Main jet
Pilot jet
Dimension ×
Pitch
M6 x 1.0
M6 x 1.0
M8 x 1.25
M12 x 1.5
M6 x 1.0
M7 x 0.75
M10 x 1.25
M6 x 1.0
M7 x 1.0
M6 x 1.0
PT 1/8
M14 x 1.25
M12 x 1.25
M8 x 1.25
M8 x 1.25
PT - 1/4
PT - 3/8
PT - 3/8
M5 x 0.8
M6 x 1.0
M6 x 1.0
–
–
–
–
–
–
N·m
9.81 to 11.2
12 to 14
40 to 44
118 to 127
9.81 to 11.2
27 to 30
54 to 58
9.81 to 11.2
27 to 30
13 to 15
15 to 19
20 to 24
33 to 37
24 to 27
24 to 27
20 to 23
30 to 58
30 to 58
4.5 to 5.3
9.81 to 11.2
9.81 to 11.2
5.9 to 11
40 to 44
58.4 to 78.9
7.9 to 11
0.98 to 2.8
0.98 to 3.9
kgf·m
2.0 to 4.0
3.0 to 6.0
3.0 to 6.0
0.45 to 0.55
1.00 to 1.15
1.00 to 1.15
0.60 to 1.2
4.0 to 4.5
5.95 to 8.05
0.80 to 1.2
0.10 to 0.29
0.10 to 0.40
1.00 to 1.15
1.2 to 1.5
4.0 to 4.5
12.0 to 13.0
1.00 to 1.15
2.7 to 3.1
5.5 to 6.0
1.00 to 1.15
2.7 to 3.1
1.3 to 1.6
1.5 to 2.0
2.0 to 2.5
3.3 to 3.8
2.4 to 2.8
2.4 to 2.8
lbf·ft
22 to 43
22 to 43
3.3 to 3.9
7.24 to 8.31
7.24 to 8.31
4.4 to 8.6
29 to 32
43.1 to 58.2
5.8 to 8.6
0.73 to 2.0
0.73 to 2.8
7.24 to 8.31
8.7 to 10
29 to 32
86.8 to 94.0
7.24 to 8.31
20 to 22
40 to 43
7.24 to 8.31
20 to 22
9.4 to 11
11 to 14
15 to 18
24 to 27
18 to 20
18 to 20
15 to 17
9Y1210318ENS0010US0
1-S13
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
[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.
Indication on top of bolt
Indication on top of nut
Unit
M6
M8
M10
M12
N·m
7.9 to 9.3
18 to 20
40 to 45
63 to 72
No-grade or 4T kgf·m
0.80 to 0.95
1.8 to 2.1
4.0 to 4.6
6.4 to 7.4
lbf·ft
5.8 to 6.8
13 to 15
29 to 33
47 to 53
No-grade or 4T
N·m
9.81 to 11.2
24 to 27
49 to 55
78 to 90
7T kgf·m
1.00 to 1.15
2.4 to 2.8
5.0 to 5.7
7.9 to 9.2
lbf·ft
7.24 to 8.31
18 to 20
37 to 41
58 to 66
M00000003ENS0013US1
1-S14
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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 %.
Compression pressure
Factory spec.
Allowable limit
1.27 MPa
13.0 kgf/cm
2
185 psi
0.88 MPa
9.0 kgf/cm
2
130 psi
9Y1210318ENS0013US0
1-S15
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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.
Top clearance Factory spec.
1.35 to 1.65 mm
0.0532 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
9Y1210318ENS0014US0
1-S16
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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.
Adjustable Cylinder Location of Piston
Valve Arrangement
Intake valve Exhaust valve
No. 1
No. 2
No. 3
: When No. 1 piston is at the compression top dead center position.
: When No. 1 piston is at the overlap position.
Intake and exhaust valve clearance (cold)
Factory spec.
0.145 to 0.185 mm
0.00571 to 0.00728 in.
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.
(1) "1TC" Mark
(2) Alignment Mark
A : Gear Case Side
9Y1210318ENS0015US0
1-S17
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
(2) Lubricating System
(3) Cooling System
ENGINE
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.
Engine oil pressure
At idle speed
At rated speed
Factory spec.
Factory spec.
Allowable limit
More than
50 kPa
0.5 kgf/cm
2
7 psi
200 to 440 kPa
2.0 to 4.5 kgf/cm
2
29 to 64 psi
150 kPa
1.5 kgf/cm
2
21 psi
Tightening torque Oil pressure switch
15 to 19 N·m
1.5 to 2.0 kgf·m
11 to 14 lbf·ft
9Y1210318ENS0016US0
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.
Deflection (A) Factory spec.
7.0 to 9.0 mm
0.28 to 0.35 in.
(A) Deflection
9Y1210318GEG0001US0
1-S18
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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.
(A) Good (B) Bad
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.
Thermostat's valve opening temperature
Temperature at which thermostat completely opens
Factory spec.
Factory spec.
69.5 to 72.5 °C
157.1 to 162.5 °F
85 °C
185 °F
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/cm
2
, 10 psi), and measure the time for the pressure to fall to 60 kPa (0.6 kgf/cm
2
,
9 psi).
3. If the measurement is less than the factory specification, replace the radiator cap.
Pressure falling time Factory spec.
More than 10 seconds for pressure fall from
90 to 60 kPa from 0.9 to 0.6 kgf/cm
2 from 10 to 9 psi
(1) Radiator Tester (2) Adaptor
9Y1210318ENS0019US0
1-S19
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
(4) Fuel System
ENGINE
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.
Radiator water leakage test pressure
Factory spec.
No leak at specified pressure
(1) Radiator Tester (2) Adaptor
9Y1210318ENS0020US0
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.
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
NOTE
• Insert the governor lever to the position 2 mm (0.08 in.) (B) away from the fork lever shaft end.
(1) Governor Lever Shaft
(2) Governor Lever
(3) Governor Lever Nut
A : Open Direction
B : 2 mm (0.08 in.)
9Y1210318ENS0021US0
1-S20
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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.
Lo-idling speed
Hi-idling speed
Factory spec.
Factory spec.
1500 min
-1
(rpm)
(1400 to 1600 min
-1
(rpm))
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
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.
(1) Tamper Resistance
9Y1210318ENS0023US0
1-S21
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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.
Tightening torque
Carburetor mounting nut
Gasoline solenoid
Main jet
Pilot jet
24 to 27 N·m
2.4 to 2.8 kgf·m
18 to 20 lbf·ft
7.9 to 11 N·m
0.80 to 1.2 kgf·m
5.8 to 8.6 lbf·ft
0.98 to 2.8 N·m
0.10 to 0.29 kgf·m
0.73 to 2.0 lbf·ft
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
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.
(1) Tamper Resistance
9Y1210318ENS0025US0
1-S22
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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.
(1) Tamper Resistance
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.
Joint for LPG hose of vaporizer
(local arrangement)
Tightening torque
Joint for vapor hose of vaporizer
Joint for coolant hose of vaporizer
20 to 23 N·m
2.0 to 4.0 kgf·m
15 to 17 lbf·ft
30 to 58 N·m
3.0 to 6.0 kgf·m
22 to 43 lbf·ft
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
9Y1210318ENS0027US0
1-S23
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
(5) Ignition System
ENGINE
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.
(1) Coolant Hose
(2) Coolant Hose
(3) Vaporizer
(4) Vacuum Lock Hose
A : Joint
9Y1210318ENS0028US0
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-S24
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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.
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
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.
Resistance
Factory spec.
A - B 1.85 to 2.45 kΩ at 20 °C
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
1-S25
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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.
Resistance
Factory spec.
A - B
A - C
1.87 to 2.53 Ω at 20 °C
10.4 to 15.6 kΩ at 20 °C
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.
A : Terminal (+)
B : Terminal (−)
C : High Tension Cord
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.
Air gap Factory spec.
0.80 to 1.2 mm
0.032 to 0.047 in.
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.
Resistance Factory spec.
Approx. 2.15 kΩ
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
1-S26
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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
Positive
A
B
C
D
E
F
G
H
A
–
11 to 47 kΩ
Infinity
2 megohm
(minimum)
2 megohm
(minimum)
2 megohm
(minimum)
B
10 to 40 kΩ
10 to 40 kΩ –
10 to 40 kΩ 0.33 to 1.3 kΩ
C
10 to 40 kΩ
Negative
D
11 to 47 kΩ
E
Infinity
F
Infinity
G
Infinity
H
Infinity
0.33 to 1.3 kΩ 1.8 to 7.3 kΩ Infinity Infinity Infinity Infinity
– 1.5 to 6.0 kΩ Infinity Infinity Infinity Infinity
Infinity Infinity Infinity Infinity
– Infinity Infinity Infinity
1.8 to 7.3 kΩ 1.5 to 6.0 kΩ
Infinity Infinity
2 megohm
(minimum)
2 megohm
(minimum)
2 megohm
(minimum)
2 megohm
(minimum)
2 megohm
(minimum)
2 megohm
(minimum)
–
Infinity
2 megohm
(minimum)
2 megohm
(minimum)
2 megohm
(minimum)
Infinity
Infinity
Infinity
–
Infinity
Infinity
Infinity
–
Infinity
Infinity
Infinity
–
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
1-S27
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
(6) Electrical System
ENGINE
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.
(1) C Terminal
(2) Positive Terminal
(3) Negative Terminal
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.
(1) S Terminal
(2) Positive Terminal
(3) Negative Terminal
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.
(1) C Terminal (2) B Terminal
9Y1210318ENS0040US0
1-S28
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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.
No-load output voltage Factory spec.
AC 20 V or more at
5200 min
-1
(rpm)
9Y1210318ENS0041US0
Regulator
1. The engine is started.
2. Measure the output voltage of the regulator with the voltmeter.
Output voltage (6) - (2) 14 V to 15 V
3. When the measurement is not the above table value, measure the input voltage of the regulator with the voltmeter.
Input voltage (1) - (3) Dynamo output voltage
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.
(1) Terminal (Sky Blue)
(2) Terminal (Black)
(3) Terminal (Sky Blue)
(4) Terminal (Green)
(5) Terminal (Yellow)
(6) Terminal (Red)
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.
Regulating voltage at no load
Factory spec.
13.8 to 14.8 V at 25 °C
(77 °F)
9Y1210318ENS0043US0
1-S29
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
(7) Electronic Governor
ENGINE
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.
WG972-E2, DF972-E2 : for Gasoline
DF972-E2 : for LPG
Factory spec.
Factory spec.
Approx. 38 Ω at 20 °C
Approx. 28 Ω at 20 °C
(1) Fuel Cut off Solenoid for Gasoline (2) Fuel Cut off Solenoid for LPG
9Y1210318ENS0044US0
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.
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
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.
(5) Governor Lever (1) Idle Adjust Screw
(2) Actuator
(3) Actuator Shaft
(4) Governor Lever Nut
A : Setting Position
9Y1210318ENS0045US0
1-S30
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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.
(1) Actuator Connector
(2) Throttle Lever
(3) Idle Adjust Screw
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.
Above 25 °C (77 °F)
0 °C to 25 °C (32 °F to 77 °F)
Below 0 °C (32 °F)
SAE30 or SAE10W-30
SAE20 or SAE10W-30
SAE10W or SAE10W-30
Engine oil capacity
3.4 L
0.90 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
9Y1210318ENS0048US0
1-S31
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
(2) External Components
ENGINE
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.
(1) Coolant Drain Cock
9Y1210318ENS0049US0
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.
(1) Cooling Fan (2) Fan Belt
9Y1210318ENS0050US0
Fuel Line (WG972-E2)
1. Disconnect the gasoline hose from the connector (1).
(1) Gasoline Hose Connector
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.
(1) Vacuum Lock Hose
(2) Vapor Hose
(3) Vaporizer
(4) LPG Hose Connector
(5) Coolant Hose
9Y1210318ENS0052US0
1-S32
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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.
(1) Gas Mixer
(2) Gas Hose
(3) Regulator
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).
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
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).
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
9Y1210318ENS0055US0
1-S33
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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).
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
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.
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
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.
(1) Idle Adjust Screw
(2) Actuator
(3) Actuator Shaft
(4) Governor Lever Nut
(5) Governor Lever
A : Setting Position
9Y1210318ENS0057US0
1-S34
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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.
(1) Connector
(2) Throttle Lever
(3) Idle Adjust Screw
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).
Tightening torque
Actuator mounting screw
Actuator flange screw
4.5 to 5.3 N·m
0.45 to 0.55 kgf·m
3.3 to 3.9 lbf·ft
9.81 to 11.2 N·m
1.00 to 1.15 kgf·m
7.24 to 8.31 lbf·ft
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.
(1) Actuator Mounting Screw
(2) Actuator
(3) Actuator Flange
(4) Actuator Flange Screw
9Y1210318ENS0059US0
1-S35
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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.
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
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.
(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.)
9Y1210318ENS0060US0
1-S36
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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).
(1) Plug Cap
(2) Ignition Coil
(3) Ignition Coil Connector
(4) Spark Plug
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.
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
9Y1210318ENS0062US0
1-S37
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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.
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
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.
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
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.
(1) Tappet
9Y1210318ENS0065US0
1-S38
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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.
(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
9Y1210318ENS0066US0
1-S39
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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.
(1) Oil Pan
(2) Oil Pan Mounting Screw
(3) Oil Strainer
(4) O-ring
(5) Hole Numbered "3"
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).
(1) Thermostat Cover Mounting Screw
(2) Thermostat Cover
(3) Thermostat Cover Gasket
(4) Thermostat Assembly
9Y1210318ENS0068US0
1-S40
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
(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.
(1) Screws and Copper Washers
(2) Speed Control Plate
(3) Governor Lever Shaft
(4) Governor Fork
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.
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
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.
(1) Screw (Inside) (2) Gear Case
9Y1210318ENS0071US0
1-S41
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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).
(1) Water Pump Flange
(2) Water Pump Assembly
(3) Water Pump Gasket
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.
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
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.
(1) Camshaft Mounting Screw (2) Camshaft Gear
9Y1210318ENS0074US0
1-S42
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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.
(1) Injection Pump Gear
(2) Governor Sleeve
(3) Fork Lever
(4) Retaining Plate
(5) Fuel Camshaft
(6) Fork Lever Holder Mounting Screw
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.
(1) Crankshaft Gear
(2) Crankshaft Oil Slinger
(3) Crankshaft Collar
(4) O-ring
(5) Oil Pump Gear
(6) Oil Pump
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.
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
9Y1210318ENS0077US0
1-S43
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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.
(1) Piston Ring Compressor
D : Side Rail Gap
E : Spacer Gap
A : Second Compression Ring Gap
B : Side Rail Gap
C : Top Compression Ring Gap
(a) 2.09 rad (120 °)
(b) 1.6 rad (90 °)
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.
(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
9Y1210318ENS0079US0
1-S44
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
(7) Crankshaft
ENGINE
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.
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
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.
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
9Y1210318ENS0081US0
1-S45
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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.
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
9Y1210318ENS0082US0
1-S46
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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.
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
9Y1210318ENS0083US0
1-S47
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
(8) Starter
ENGINE
(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
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)
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
9Y1210318ENS0084US0
1-S48
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
(9) Dynamo
(1) Shaft
(2) Pulley
(3) Rotor
(4) Collar
(5) Bearing
(6) Stator
(7) Plate
(8) Bearing
ENGINE
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.
Tightening torque Dynamo's pulley nut
40 to 44 N·m
4.0 to 4.5 kgf·m
29 to 32 lbf·ft
9Y1210318ENS0085US0
1-S49
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
(10) Alternator
(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
ENGINE
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)
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
9Y1210318ENS0086US0
1-S50
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
[3] SERVICING
(1) Cylinder Head and Valves
ENGINE
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.
Cylinder head surface flatness
Allowable limit
0.05 mm
0.002 in.
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.
(1) Red Permeative Liquid
(2) Detergent
(3) White Developer
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.
Valve recessing (Intake and Exhaust)
Factory spec.
Allowable limit
0.10 (protrusion) to
0.10 (recessing) mm
0.0039 (protrusion) to
0.0039 (recessing) in.
0.30 (recessing) mm
0.012 (recessing) in.
(1) Cylinder Head Surface
(A) Recessing
(B) Protrusion
9Y1210318ENS0089US0
1-S51
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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.
Clearance between valve stem and valve guide
Factory spec.
Allowable limit
0.030 to 0.057 mm
0.0012 to 0.0022 in.
0.10 mm
0.0039 in.
Valve stem O.D.
Valve guide I.D.
Factory spec.
Factory spec.
5.968 to 5.980 mm
0.2350 to 0.2354 in.
6.010 to 6.025 mm
0.2367 to 0.2372 in.
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.
Valve guide I.D.(Intake and exhaust)
Factory spec.
6.010 to 6.025 mm
0.2367 to 0.2372 in.
IMPORTANT
• Do not hit the valve guide with a hammer during replacement.
(A) When Removing (B) When Installing
9Y1210318ENS0091US0
1-S52
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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.
Valve seat width Factory spec.
2.12 mm
0.0835 in.
(1) Correct
(2) Incorrect
(3) Incorrect
9Y1210318ENS0092US0
1-S53
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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.
Valve face angle Factory spec.
0.79 rad
45 °
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.
Valve seat angle Factory spec.
0.79 rad
45 °
(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 °)
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
1-S54
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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.
Tilt (A) Allowable limit
1.0 mm
0.039 in.
Free length (B)
Factory spec.
Allowable limit
31.3 to 31.8 mm
1.24 to 1.25 in.
28.4 mm
1.12 in.
(A) Tilt (B) Free length
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.
Setting load / setting length
Factory spec.
Allowable limit
65 N / 27.0 mm
6.6 kgf / 27.0 mm
15 lbf / 1.06 in.
55 N / 27.0 mm
5.6 kgf / 27.0 mm
12 lbf / 1.06 in.
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.
Oil clearance between rocker arm and rocker arm shaft
Factory spec.
Allowable limit
0.016 to 0.045 mm
0.00063 to 0.0017 in.
0.15 mm
0.0059 in.
Rocker arm shaft O.D.
Rocker arm I.D.
Factory spec.
Factory spec.
10.473 to 10.484 mm
0.41233 to 0.41275 in.
10.500 to 10.518 mm
0.41339 to 0.41409 in.
9Y1210318ENS0097US0
1-S55
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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.
Push rod alignment Allowable limit
0.25 mm
0.0098 in.
9Y1210318ENS0098US0
(2) Timing Gear and Camshaft
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.
Oil clearance between tappet and tappet guide bore
Factory spec.
Allowable limit
0.016 to 0.052 mm
0.00063 to 0.0020 in.
0.10 mm
0.0039 in.
Tappet O.D.
Tappet guide bore I.D.
Factory spec.
Factory spec.
17.966 to 17.984 mm
0.70733 to 0.70803 in.
18.000 to 18.018 mm
0.70867 to 0.70937 in.
9Y1210318ENS0099US0
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.
Backlash between idle gear and crank gear
Factory spec.
Allowable limit
0.0430 to 0.124 mm
0.00170 to 0.00488 in.
0.15 mm
0.0059 in.
Backlash between idle gear and cam gear
Backlash between idle gear and injection pump gear
Factory spec.
Allowable limit
Backlash between oil pump drive gear and crank gear
Factory spec.
Allowable limit
Factory spec.
Allowable limit
0.0470 to 0.123 mm
0.00185 to 0.00484 in.
0.15 mm
0.0059 in.
0.0410 to 0.124 mm
0.00162 to 0.00488 in.
0.15 mm
0.0059 in.
0.0410 to 0.123 mm
0.00162 to 0.00484 in.
0.15 mm
0.0059 in.
9Y1210318ENS0100US0
1-S56
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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.
Idle gear side clearance
Factory spec.
Allowable limit
0.20 to 0.51 mm
0.0079 to 0.020 in.
0.80 mm
0.031 in.
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.
Camshaft side clearance
Factory spec.
Allowable limit
0.15 to 0.31 mm
0.0059 to 0.012 in.
0.50 mm
0.020 in.
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.
Camshaft alignment Allowable limit
0.01 mm
0.0004 in.
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.
Cam height of intake and exhaust
Factory spec.
Allowable limit
26.88 mm
1.058 in.
26.83 mm
1.056 in.
9Y1210318ENS0104US0
1-S57
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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.
Oil clearance of camshaft journal
Factory spec.
Allowable limit
0.050 to 0.091 mm
0.0020 to 0.0035 in.
0.15 mm
0.0059 in.
Camshaft journal O.D.
Camshaft bearing I.D.
(Cylinder block bore I.D.)
Factory spec.
Factory spec.
32.934 to 32.950 mm
1.2967 to 1.2972 in.
33.000 to 33.025 mm
1.2993 to 1.3001 in.
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.
Oil clearance between idle gear shaft and idle gear bushing
Factory spec.
Allowable limit
0.020 to 0.084 mm
0.00079 to 0.0033 in.
0.10 mm
0.0039 in.
Idle gear shaft O.D.
Idle gear bushing I.D.
Factory spec.
Factory spec.
19.967 to 19.980 mm
0.78611 to 0.78661 in.
20.000 to 20.051 mm
0.78741 to 0.78940 in.
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.
(A) When Removing (B) When Installing
9Y1210318ENS0107US0
1-S58
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
(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.
Piston pin bore I.D.
Factory spec.
Allowable limit
20.000 to 20.013 mm
0.78741 to 0.78791 in.
20.05 mm
0.7894 in.
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.
Oil clearance between piston pin and small end bushing
Factory spec.
Allowable limit
0.012 to 0.038 mm
0.00048 to 0.0014 in.
0.10 mm
0.0039 in.
Piston pin O.D.
Small end bushing I.D.
Factory spec.
Factory spec.
20.002 to 20.013 mm
0.78748 to 0.78791 in.
20.025 to 20.040 mm
0.78839 to 0.78897 in.
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]
Oil clearance between piston pin and small end bushing (Spare parts)
Factory spec.
Allowable limit
0.013 to 0.075 mm
0.00052 to 0.0029 in.
0.15 mm
0.0059 in.
Small end bushing I.D.
(Spare parts)
(1) Seam
(2) Oil Hole
Factory spec.
20.026 to 20.077 mm
0.78843 to 0.79043 in.
(A) When Removing
(B) When Installing
(a) 0.79 rad (45 °)
9Y1210318ENS0110US0
1-S59
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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.
Piston ring gap
Top ring
Second ring
Oil ring
Factory spec.
Allowable limit
Factory spec.
Allowable limit
Factory spec.
Allowable limit
0.15 to 0.35 mm
0.0059 to 0.013 in.
1.25 mm
0.0492 in.
0.30 to 0.45 mm
0.012 to 0.017 in.
1.25 mm
0.0492 in.
0.20 to 0.70 mm
0.0079 to 0.027 in.
1.25 mm
0.0492 in.
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.
Clearance between piston ring and piston ring groove
Top ring
Second ring
Oil ring
Factory spec.
Allowable limit
Factory spec.
Allowable limit
Factory spec.
Allowable limit
0.080 to 0.12 mm
0.0032 to 0.0047 in.
0.15 mm
0.0059 in.
0.065 to 0.10 mm
0.0026 to 0.0039 in.
0.15 mm
0.0059 in.
0.060 to 0.15 mm
0.0024 to 0.0059 in.
0.20 mm
0.0079 in.
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.
Space between gauge pin face plate
Allowable limit
0.05 mm
0.002 in.
9Y1210318ENS0113US0
1-S60
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
(4) Crankshaft
ENGINE
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.
Crankshaft side clearance
Factory spec.
Allowable limit
0.15 to 0.31 mm
0.0059 to 0.012 in.
0.50 mm
0.020 in.
(Reference)
• Oversize thrust bearing
Oversize
0.2 mm
0.008 in.
Bearing
Thrust bearing 1 02
Thrust bearing 2 02
Code Number
15261-23950
15261-23970
0.4 mm
0.02 in.
Thrust bearing 1 04
Thrust bearing 2 04
15261-23960
15261-23980
• Oversize dimensions of crankshaft journal
Marking
020 OS
020 OS
040 OS
040 OS
Oversize
Dimension A
0.2 mm
0.008 in.
46.10 to 46.30 mm
1.815 to 1.822 in.
0.4 mm
0.02 in.
46.30 to 46.50 mm
1.823 to 1.830 in.
Dimension B
23.40 to 23.45 mm
0.9213 to 0.9232 in.
23.60 to 23.65 mm
0.9292 to 0.9311 in.
Dimension C
1.8 to 2.2 mm radius
0.071 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
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.
Crankshaft alignment Allowable limit
0.02 mm
0.0008 in.
9Y1210318ENS0115US0
1-S61
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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.
Oil clearance between crankpin and crankpin bearing
Factory spec.
Allowable limit
0.020 to 0.051 mm
0.00079 to 0.0020 in.
0.15 mm
0.0059 in.
Crankpin O.D.
Crankpin bearing I.D.
Factory spec.
Factory spec.
33.959 to 33.975 mm
1.3370 to 1.3375 in.
33.995 to 34.010 mm
1.3384 to 1.3389 in.
(Reference)
• Undersize crankpin bearing
Undersize Bearing Code Number
0.2 mm
0.008 in.
Crankpin bearing 02
0.4 mm
0.02 in.
Crankpin bearing 04
• Undersize dimensions of crankpin
15861-22970
15861-20980
Marking
020 US
040 US
Undersize
Dimension A
0.2 mm
0.008 in.
2.3 to 2.7 mm radius
0.091 to 0.10 in. radius
0.4 mm
0.02 in.
2.3 to 2.7 mm radius
0.091 to 0.10 in. radius
*Dimension B
Dimension C
1.0 to 1.5 mm relief
0.040 to 0.059 in. relief
33.759 to 33.775 mm dia.
1.3291 to 1.3297 in. dia.
1.0 to 1.5 mm relief
0.040 to 0.059 in. relief
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.
9Y1210318ENS0116US0
1-S62
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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.
Oil Clearance between crankshaft journal and crankshaft bearing 1
Factory spec.
Allowable limit
0.0340 to 0.106 mm
0.00134 to 0.00417 in.
0.20 mm
0.0079 in.
Crankshaft journal O.D.
Factory spec.
Crankshaft bearing 1 I.D.
Factory spec.
43.934 to 43.950 mm
1.7297 to 1.7303 in.
43.984 to 44.040 mm
1.7317 to 1.7338 in.
(Reference)
• Undersize crankshaft bearing 1
Undersize
0.2 mm
0.008 in.
Bearing
Crankshaft bearing 1 02
Code Number
1G460-23910
0.4 mm
0.02 in.
Crankshaft bearing 1 04 1G460-23920
• Undersize dimensions of crankshaft journal
Marking
020 US
040 US
Undersize
Dimension A
*Dimension B
0.2 mm
0.008 in.
1.8 to 2.2 mm radius
0.071 to 0.086 in. radius
1.0 to 1.5 mm relief
0.040 to 0.059 in. relief
0.4 mm
0.02 in.
1.8 to 2.2 mm radius
0.071 to 0.086 in. radius
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.
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.)
Dimension (A) Factory spec.
0 to 0.3 mm
0 to 0.01 in.
(1) Seam
(2) Crankshaft Bearing 1
(3) Cylinder Block
(A) Dimension
(a) 0.37 rad (21 °)
9Y1210318ENS0118US0
1-S63
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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.
Oil clearance between crankshaft journal and crankshaft bearing 2
(crankshaft bearing 3)
Factory spec.
Allowable limit
0.028 to 0.059 mm
0.0011 to 0.0023 in.
0.20 mm
0.0079 in.
Crankshaft journal O.D.
(Flywheel side)
Factory spec.
Crankshaft bearing 2 I.D.
Factory spec.
43.934 to 43.950 mm
1.7297 to 1.7303 in.
43.978 to 43.993 mm
1.7315 to 1.7320 in.
Crankshaft journal O.D.
(Intermediate)
Factory spec.
Crankshaft bearing 3 I.D.
Factory spec.
43.934 to 43.950 mm
1.7297 to 1.7303 in.
43.978 to 43.993 mm
1.7315 to 1.7320 in.
(Reference)
• Undersize crankshaft bearing 2 and 3
Undersize
0.2 mm
0.008 in.
0.4 mm
0.02 in.
Bearing
Crankshaft bearing 2 02
Code Number
15694-23930
Crankshaft bearing 2F 02 1G460-07530
Crankshaft bearing 3 02 1G460-07580
Crankshaft bearing 3F 02 1G460-07630
Crankshaft bearing 2 04 15694-23940
Crankshaft bearing 2F 04 1G460-07540
Crankshaft bearing 3 04 1G460-07590
Crankshaft bearing 3F 04 1G460-07640
• Undersize dimensions of crankshaft journal
Marking
020 US
020 US
040 US
040 US
Undersize
Dimension A
0.2 mm
0.008 in.
1.8 to 2.2 mm radius
0.071 to 0.086 in. radius
0.4 mm
0.02 in.
1.8 to 2.2 mm radius
0.071 to 0.086 in. radius
*Dimension B
1.0 to 1.5 mm relief
0.040 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.
9Y1210318ENS0119US0
1-S64
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
(5) Cylinder
ENGINE
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.
Cylinder I.D.
Factory spec.
Allowable limit
74.500 to 74.519 mm
2.9331 to 2.9338 in.
74.669 mm
2.9397 in.
(A) Top
(B) Middle
(C) Bottom (Skirt)
(a) Right-Angled to Piston Pin
(b) Piston Pin Direction
9Y1210318ENS0120US0
Correcting Cylinder (Oversize)
1. When the cylinder is worn beyond the allowable limit, bore and hone it to the specified dimension.
Cylinder liner I.D.
Factory spec.
Allowable limit
75.000 to 75.019 mm
2.9528 to 2.9535 in.
75.150 mm
2.9587 in.
Finishing
Hone to 2.2 to 3.0 µmRz
(0.000087 to 0.00011 in.Rz)
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.
(1) Cylinder I.D. (Before Correction) (2) Cylinder I.D. (Oversize)
9Y1210318ENS0121US0
1-S65
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
(6) Oil Pump
ENGINE
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.
Rotor lobe clearance Factory spec.
0.030 to 0.14 mm
0.0012 to 0.0055 in.
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.
Clearance between outer rotor and pump body
Factory spec.
0.070 to 0.15 mm
0.0028 to 0.0059 in.
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.
Clearance between rotor and cover
Factory spec.
0.0750 to 0.135 mm
0.00296 to 0.00531 in.
9Y1210318ENS0124US0
1-S66
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
(7) Starter
ENGINE
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.
Commutator O.D.
Factory spec.
Allowable limit
28.0 mm
1.10 in.
27.0 mm
1.06 in.
Difference of O.D.'s
Mica under cut
Factory spec.
Allowable limit
Factory spec.
Allowable limit
Less than
0.05 mm
0.002 in.
0.4 mm
0.02 in.
0.45 to 0.75 mm
0.018 to 0.029 in.
0.2 mm
0.008 in.
(1) Segment
(2) Undercut
(3) Mica
(a) Good
(b) Bad
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.
Brush length (A)
Factory spec.
Allowable limit
14.0 mm
0.551 in.
11.1 mm
0.437 in.
(A) Brush Length
9Y1210318ENS0127US0
1-S67
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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.
(1) Lead
(2) Brush
(3) Yoke
9Y1210318ENS0130US0
1-S68
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
(8) Alternator
ENGINE
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.
Resistance Factory spec.
Less than 1.0 Ω
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.
Resistance Factory spec.
2.9 Ω
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.
Slip ring O.D.
Factory spec.
Allowable limit
14.4 mm
0.567 in.
14.0 mm
0.551 in.
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.
Brush length
Factory spec.
Allowable limit
10.5 mm
0.413 in.
8.4 mm
0.33 in.
9Y1210318ENS0135US0
1-S69
KiSC issued 06, 2009 A
WG972-E2,DF972-E2,DG972-E2, WSM
ENGINE
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.
(1) F Terminal (2) B Terminal
9Y1210318ENS0137US0
1-S70
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 : [email protected]
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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Key features
- Gasoline, LPG, and Natural Gas Fuel Options
- 3-Cylinder Vertical Design
- Water-Cooled 4-Cycle Operation
- Overhead-Valve Cylinder Head
- Distributor-Less Solid State Ignition System
- Centrifugal Ball Mechanical Governor
- Forced Lubrication System
- Pressurized Radiator Cooling
- Electric Starting System