Kubota WG972-E2 Instruction manual

WORKSHOP MANUAL
GASOLINE,LPG ENGINE
WG972-E2,DF972-E2
KiSC issued 01, 2006 A

TO THE READER
This Workshop Manual has been prepared to provide servicing personnel with
information on the mechanism, service and maintenance of KUBOTA Gasoline / LPG
Fuel Engine WG972-E2 and DF972-E2. It is divided into three parts, "General",
"Mechanism" and "Servicing".
■General
Information on the general precautions, check and maintenance and special tools.
■Mechanism
Information on the construction and function are included. This part should be
understood before proceeding with troubleshooting, disassembling and servicing.
■Servicing
There are troubleshooting, servicing specification lists, checking and adjusting,
disassembling and assembling, and servicing which cover procedures, precautions,
factory specifications and allowable limits.
All information illustrations and specifications contained in this manual are based on
the latest product information available at the time of publication.
The right is reserved to make changes in all information at any time without notice.
July 2005
© KUBOTA Corporation 2005
KiSC issued 01, 2006 A

1
WG972-E2, DF972-E2, WSM SAFETY INSTRUCTIONS
SAFETY INSTRUCTIONS
BEFORE SERVICING AND REPAIRING
•Readallinstructionsandsafetyinstructionsinthis
manual and on your generator safety decals.
•Cleantheworkareaandgenerator.
•Parkthemachineonafirmandlevelground,andset
the parking brake.
•Lowertheimplementtotheground.
•Stoptheengine,andremovethekey.
•Disconnectthebatterynegativecable.
•Hanga “DO NOT OPERATE” tag in operator
station.
SAFETY FIRST
This symbol, the industry’s “Safety Alert Symbol”, is used throughout this manual and on labels on
the machine itself to warm of the possibility of personal injury. Read these instructions carefully.
It is essential that you read the instructions and safety regulations before you attempt to repair or use
this unit.
DANGER : Indicates an imminently hazardous situation which, if not avoided, will result in
death or serious injury.
WARNING : Indicates a potentially hazardous situation which, if not avoided, could result in
death or serious injury.
CAUTION : Indicates a potentially hazardous situation which, if not avoided, may result in
minor or moderate injury.
■IMPORTANT : Indicates that equipment or property damage could result if instructions are not
followed.
■NOTE : Gives helpful information.
KiSC issued 01, 2006 A

2
WG972-E2, DF972-E2, WSM SAFETY INSTRUCTIONS
SAFETY STARTING
•Donotstarttheenginebyshortingacrossstarter
terminals or bypassing the safety start switch.
•Donotalterorremoveanypartofmachinesafety
system.
•Beforestartingtheengine,makesurethatallshift
levers are in neutral positions or in disengaged
positions.
•Neverstarttheenginewhilestandingonground.
Start the engine only from operator’s seat.
SAFETY WORKING
•Donotworkonthemachinewhileundertheinfluence
of alcohol, medication, or other substances or while
fatigued.
•Wearclosefittingclothingandsafetyequipment
appropriate to the job.
•Usetoolsappropriatetothework.Markshifttools,
parts, and procedures are not recommended.
•Whenservicingisperformedtogetherbytwoormore
persons, take care to perform all work safely.
•Donotworkunderthemachinethatissupported
solely by a jack. Always support the machine by
safety stands.
•Donottouchtherotatingorhotpartswhiletheengine
is running.
•Neverremovetheradiatorcapwhiletheengineis
running, or immediately after stopping. Otherwise, hot
water will spout out from radiator. Only remove
radiator cap when cool enough to touch with bare
hands. Slowly loosen the cap to first stop to relieve
pressure before removing completely.
•Escapingfluid(fuelorhydraulicoil)underpressure
can penetrate the skin causing serious injury. Relieve
pressure before disconnecting hydraulic or fuel lines.
Tighten all connections before applying pressure.
AVOID FIRES
•Fuelisextremelyflammableandexplosiveunder
certain conditions. Do not smoke or allow flames or
sparks in your working area.
•Toavoidsparksfromanaccidentalshortcircuit,
always disconnect the battery negative cable first and
connect it last.
•Batterygascanexplode.Keepsparksandopen
flame away from the top of battery, especially when
charging the battery.
•Marksurethatnofuelhasbeenspilledontheengine.
KiSC issued 01, 2006 A

3
WG972-E2, DF972-E2, WSM SAFETY INSTRUCTIONS
VENTILATE WORK AREA
•Iftheenginemustberunningtodosamework,make
sure the area is well ventilated. Never run the engine
in a closed area. The exhaust gas contains poisonous
carbon monoxide.
PREVENT ACID BURNS
•Sulfuricacidinbatteryelectrolyteispoisonous.Itis
strong enough to burn skin, clothing and cause
blindness if splashed into eyes. Keep electrolyte
away from eyes, hands and clothing. If you spill
electrolyte on yourself, flush with water, and get
medical attention immediately.
DISPOSE OF FLUIDS PROPERLY
•Donotpourfluidsintotheground,downadrain,or
into a stream, pond, or lake. Observe relevant
environmental protection regulations when disposing
of oil, fuel, coolant, electrolyte and other harmful
waste.
PREPARE FOR EMERGENCIES
•Keepafirstaidkitandfireextinguisherhandyatall
times.
•Keepemergencynumbersfordoctors,ambulance
service, hospital and fire department near your
telephone.
KiSC issued 01, 2006 A

4
WG972-E2, DF972-E2, WSM IMPORTANT ITEMS OF EXHAUST EMISSION REGULATION
IMPORTANT ITEMS OF EXHAUST EMISSION
REGULATION
W1028060
W1028104
W1034885
■To c o nf or m w it h U. S. E PA a n d C AR B S OR E s ( S m a ll O ff R o ad E n g i n e s) e m i s s io n r e g u l at io ns , t h e W G9 7 2- E 2 /
DF972-E2 engine must observe below items.
1. INLET AND EXHAUST SYSTEM
The WG972-E2 / DF972-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 Part No.
Genuine air cleaner 1G657-1101-1
Genuine inlet pipe EG561-1164-1
Brake horse power SAE net int. Allowable maximum exhaust back pressure
23.1 kW (31.0 HP) / 3600 min−1(rpm) 19.6 kPa (147.1 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.
2. ALTITUDE COMPENSATION KIT
■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 the 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 engines must comply with the regulations
through the installation of the appropriate altitude compensation kit for the altitude range where the
engine will be operated.
●See page S-19: "Replacement of Altitude Compensation Kit" for reference to the exchange of altitude
compensation kit.
Altitude Compensation Kit Applicable Altitude Ranges
Original Carburetor (with 0 m kit)
1000 m compensation kit
2000 m compensation kit
3. LPG REGULATOR WITH VAPORIZER (DF972-E2)
When operating DF972-E2 on LP Gas, only a KUBOTA GENUINE LPG REGULATOR KIT can be used.
KiSC issued 01, 2006 A

5
WG972-E2, DF972-E2, WSM IMPORTANT ITEMS OF EXHAUST EMISSION REGULATION
*GPA means Gas Processors Association (U.S.A.)
W1028533
4. KUBOTA RECOMMENDED LPG FUEL SPECIFICATIONS (DF972-E2)
· Commercial Propane gas only.
· Equivalent to Propanes H-D-5 of GPA* standards.
(vol %)
C3H8C3H6C4H10 Others
90 % 5 % 2.5 % –
5. LENGTH OF THE LPG VAPOR HOSE (DF972-E2)
The length of the LPG vapor hose between the LPG carburetor and its regulator must be within 280 to 320 mm
(11.02 to 12.60 in.).
The incorrect use of the hose may not conform to EPA and CARB EMISSION REGULATIONS.
KiSC issued 01, 2006 A

6
WG972-E2, DF972-E2, WSM SPECIFICATIONS
SPECIFICATIONS
* The specification described above is of the standard engine of each model.
* Conversion Formula : HP = 0.746 kW, PS = 0.7355 kW
W1028103
Model WG972-E2 DF972-E2
Number of Cylinder 3
Type Vertical, water cooled, 4-cycle
Gasoline engine
Vertical, water cooled, 4-cycle Dual Fuel (Gasoline / LPG) engine
Gasoline fuel LPG fuel
Bore ×Stroke 74.5 x 73.6 mm (2.93 x 2.90 in.)
Total Displacement 962 cm3(58.70 cu.in.)
ISO Net Continuous 18.7 kW / 3600 min-1 (rpm)
25.0 HP / 3600 min-1 (rpm)
17.5 kW / 3600 min-1 (rpm)
23.5 HP / 3600 min-1 (rpm)
ISO / SAE Net Intermittent 23.1 kW / 3600 min-1 (rpm)
31.0 HP / 3600 min-1 (rpm)
22.0 kW / 3600 min-1 (rpm)
29.5 HP / 3600 min-1 (rpm)
SAE Gross Intermittent 24.2 kW / 3600 min-1 (rpm)
32.5 HP / 3600 min-1 (rpm)
23.1 kW / 3600 min-1 (rpm)
31.0 HP / 3600 min-1 (rpm)
Maximum Bare Speed 3850 to 3950 min-1 (rpm)
Minimum Bare Idling Speed 1400 to 1600 min-1 (rpm)
Cylinder Head Overhead-Valve
Ignition System Distributor-Less Solid Stage Type
Governor Centrifugal Ball Mechanical Type / Electronic Governor
Direction of Rotation Counter-Clockwise (Viewed from flywheel)
Spark Plug NGK BKR4E
Ignition Timing 0.366 rad (21 °) before T.D.C. / 3600 min-1 (rpm)
Firing Order 1-2-3
Compression Ratio 9.2 : 1
Lubricating System Forced Lubrication by Trochoid Pump
Oil Pressure Indication Electrical Type Switch
Lubricating Filter Full Flow Paper Filter (Cartridge Type)
Cooling System Pressurized Radiator (not included in the basic model), Forced Circulation with Water Pump
Starting System Electric Starting with Starter
Starting Motor 12V, 1.0 kW
Battery 12 V, 2.5 kW
Charging Alternator 12 V, 150 W
Fuel *Unleaded Automobile Gasoline Standard Commercial LP Gas
Lubricating Oil Better than SH Class (API)
Lubricating Oil Capacity 3.4 L (3.59 U.S.qts)
Weight (Dry) 72.0 kg (158.7 lbs)
Application General Power Source
KiSC issued 01, 2006 A

7
WG972-E2, DF972-E2, WSM SPECIFICATIONS
*GPA means Gas Processors Association (U.S.A.)
W1032351
KUBOTA RECOMMENDED LPG FUEL SPECIFICATIONS
· Commercial Propane gas only.
· Equivalent to Propanes H-D-5 of GPA* standards.
(vol %)
C3H8C3H6C4H10 Others
90 % 5 % 2.5 % –
KiSC issued 01, 2006 A

8
WG972-E2, DF972-E2, WSM PERFORMANCE CURVES
PERFORMANCE CURVES
(1) Brake Horsepower
(2) Engine Speed
(3) Specific Fuel Consumption
(4) Torque
(5) Net Intermittent Torque
(6) Net Continuous Torque
(7) Net Intermittent Brake
Horsepower
(8) Net Continuous Brake
Horsepower
(9) Net Intermittent Specific Fuel
Consumption
a : Gasoline Use
b : LP Gas Use
KiSC issued 01, 2006 A

9
WG972-E2, DF972-E2, WSM DIMENSIONS
DIMENSIONS
KiSC issued 01, 2006 A

10
WG972-E2, DF972-E2, WSM DIMENSIONS
Electronic Governor Model
KiSC issued 01, 2006 A

11
WG972-E2, DF972-E2, WSM WIRING DIAGRAM
WIRING DIAGRAM
WIRE HARNESS (IGNITER)
B ........ Black BY ...... Black / Yellow GW ...... Green / White LW....... Blue / White R ....... Red Y ...... Yellow
BOr ......Black / Red Br ....... Brown Gr...... Gray Or ....... Orange RB ...... Red / Black YW ....... Yellow / White
BR ........Black / Red G ....... Green L....... Blue Pi ....... Pink RW ...... Red / White
BW ...... Black / White GY ..... Green / Yellow LB ...... Blue / Black Pu ...... Purple W ...... White
Color of Wiring
Igniter Sensor Assy, Crank Position
Ignition Coil
Engine Speed Pulse Output
Sensor
IG 1
IG 3
IG 2
WIRE HARNESS (IGNITER)
Engine Speed Sensor
WIRE HARNESS (ELECTRONIC GOVERNOR)
Electronic Governor
Select Switch
Relay
Driver
Power Input
(Gasoline)
Solenoid
Valve
Cavbuleter
Fuel Pump
Pilot Box Assy
Starter Battery
Fuse
Charge
Lamp
Water Temp
Lamp
Oil (-)
Fuse
Starter Switch
50 30
19 AC
50 30
19 AC
17
30
19
50 AC
19 AC30 17 50
Terminal
Position
3
2
1
0
Alternator
Water Temp
Switch
Oil Switch
1342
1342
8657
8657
B
LE
IG
BR BYWB
BR BYWB
LRGW
LRGW
10 A
0.85
0.5 BY
0.5 G
0.5 B
3 R
2 BW
0.5 W
0.5 L
0.5 BY
0.5 G
0.5 B
3 R
2 BW
0.5 W
0.5 L
(12 V, 17.3 , 0.7 A)
(1.5 A, 12 V)
1
2
ER
12 V
OV
10
9
5
4
1
6
7
12
3
11
2
8
MPU +
+ 5 V
Aux 1 +
MPU - Aux -
GND
12 P
-
-
+
+
+
+
12 V
A
J
K
L
I
H
F
G
E
J
K
L
I
H
F
G
E
D
C
B
Or
LB
WB
RB
Or
Or
Or
LB
WB
RB
B
R
B
R
G
L1
2
1
2
1
2
1
2
AVX 0.75 f
5.5A, AVX 0.75 f
RW
3 R 3 R
AVX 2
AVX 3
2 R
3EBAAABZP002A
KiSC issued 01, 2006 A

CONTENTS
GENERAL
1. ENGINE IDENTIFICATION ............................................................................. G-1
[1] MODEL NAME AND ENGINE SERIAL NUMBER ................................ G-1
[2] CYLINDER NUMBER ............................................................................... G-3
2. GENERAL PRECAUTIONS ............................................................................ G-4
3. MAINTENANCE CHECK LIST ....................................................................... G-5
4. CHECK AND MAINTENANCE....................................................................... G-6
[1] DAILY CHECK POINTS........................................................................... G-6
[2] CHECK POINTS OF INITIAL 50 HOURS ............................................. G-8
[3] CHECK POINTS OF EVERY 50 HOURS............................................. G-9
[4] CHECK POINTS OF EVERY 100 HOURS ......................................... G-10
[5] CHECK POINTS OF EVERY 200 HOURS ......................................... G-12
[6] CHECK POINTS OF EVERY 1000 HOURS ....................................... G-14
[7] CHECK POINTS OF EVERY 1 YEAR ................................................ G-16
[8] CHECK POINTS OF EVERY 2 YEARS............................................... G-19
5. SPECIAL TOOLS .......................................................................................... G-22
KiSC issued 01, 2006 A

G-1
WG972-E2, DF972-E2, WSM G 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
W1010477
Alphabet or
Number Yea r Alphabet or Number Year
1 2001 F 2015
2 2002 G 2016
3 2003 H 2017
4 2004 J 2018
5 2005 K 2019
6 2006 L 2020
7 2007 M 2021
8 2008 N 2022
9 2009 P 2023
A 2010 R 2024
B2011S2025
C 2012 T 2026
D 2013 V 2027
E 2014
a : Engine Model Name and Serial
Number
[A] WG972-E2
[B] DF972-E2
KiSC issued 01, 2006 A

G-2
WG972-E2, DF972-E2, WSM G GENERAL
•Month of manufacture
e.g. DF972-4A0001
"WG" indicates Water Cooled and Gasoline Engine.
"DF" indicates Dual Fuel Engine.
"4" indicates 2004 and "A" indicates January.
So, 4A indicates that the engine was manufactured on January,
2004.
W1011076
■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.
W1025355
Month Engine Serial Number
0001 ~ 9999 10000 ~
January A0001 ~ A9999 B0001 ~
February C0001 ~ C9999 D0001 ~
March E0001 ~ E9999 F0001 ~
April G0001 ~ G9999 H0001 ~
May J0001 ~ J9999 K0001 ~
June L0001 ~ L9999 M0001 ~
July N0001 ~ N9999 P0001 ~
August Q0001 ~ Q9999 R0001 ~
September S0001 ~ S9999 T0001 ~
October U0001 ~ U9999 V0001 ~
November W0001 ~ W9999 X0001 ~
December Y0001 ~ Y9999 Z0001 ~
KiSC issued 01, 2006 A

G-3
WG972-E2, DF972-E2, WSM G 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.
W1025903
[2] CYLINDER NUMBER
The cylinder numbers of KUBOTA gasoline / LPG 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.
W1011077
(1) Tamper Resistance [A] Carburetor
[B] Pick-up Sensor
[C] Vaporizer
KiSC issued 01, 2006 A

G-4
WG972-E2, DF972-E2, WSM G GENERAL
2. GENERAL PRECAUTIONS
•Duringdisassembly,carefullyarrangeremovedpartsinaclean
area to prevent confusion later. Screws, bolts and nuts should be
replaced in their original position to prevent reassembly errors.
•Whenspecialtoolsarerequired,useKUBOTAgenuinespecial
tools. Special tools which are not frequently used should be
made according to the drawings provided.
•Beforedisassemblingorservicinglivewires,makesureto
always disconnect the grounding cable from the battery first.
•Removeoilanddirtfrompartsbeforemeasuring.
•UseonlyKUBOTAgenuinepartsforpartsreplacementto
maintain engine performance and to ensure safety.
•GasketsandO-ringsmustbereplacedduringreassembly.
Apply grease to new O-rings or oil seals before assembling.
•Whenreassemblingexternalorinternalsnaprings,positionthem
so that the sharp edge faces against the direction from which
force is applied.
•Besuretoperformrun-intheservicedorreassembledengine.
Do not attempt to give heavy load at once, or serious damage
may result to the engine.
W1011734
(1) Grease
(2) Force
(3) Place the Sharp Edge against the
Direction of Force
(A) External Snap Ring
(B) Internal Snap Ring
KiSC issued 01, 2006 A

G-5
WG972-E2, DF972-E2, WSM G 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.)
★Change engine oil and replace oil filter cartridge after the firtst 50 hours of operation.
* Replace the element after 6 times cleaning.
CAUTION
•Whenchangingorinspecting,besuretolevelandstoptheengine.
Item
Service Interval
Daily Every 50
hrs
Every
100 hrs
Every
200 hrs
Every 1
year
Every
1000 hrs
Every 2
years
Changing LPG fuel connector ✩
Checking engine oil level ✩
Checking and replenish coolant ✩
Checking gasoline fuel hose and clamp bands ✩
Changing LPG fuel hose and clamp bands ✩
Cleaning air cleaner element ✩
Checking battery electrolyte level ✩
Checking spark plug ✩
Cleaning fuel filter ✩
Check fan belt tension and damage ✩
Replacing oil filter cartridge ★✩
Changing engine oil ★✩
Check LPG tank setting condition ✩
Checking radiator hoses and clamp bands ✩
*Replacing air cleaner element ✩
Replacing gosoline fuel hose and clamp bands ✩
Cleaning carburetor ✩
Cleaning fuel tank inside ✩
Replacing spark plug ✩
Checking coolant hose of LPG vaporizer ✩
Checking vacume lock hose of LPG vaporizer ✩
Changing radiator coolant (L.L.C.) ✩
Cleaning water jacket and radiator inteirior ✩
Checking valve clearance ✩
Cleaning cylinder head ✩
Checking valve seats ✩
Replacing intake air line ✩
Replacing fuel filter ✩
Replacing LPG fuel hose and clamp bands ✩
Replacing coolant hose of LPG vaporizer ✩
Replacing vacume lock hose of LPG vaporizer ✩
Replacing battery ✩
Replacing radiator hoses and clamp bands ✩
KiSC issued 01, 2006 A

G-6
WG972-E2, DF972-E2, WSM G 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
■
•Whenusinganoilofdifferentmakerorviscosityfromthe
previous one, drain old oil. Never mix two different types of
oil.
IMPORTANT
■
•UsetheproperSAEEngineoilaccordingtoambient
temperatures.
NOTE■
•Besuretoinspecttheengine,locatingitonahorizontal
place. If placed on gradients, accurately, oil quantity may
not be measured.
•Besuretokeeptheoillevelbetweenupperandlowerlimits
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.
W1035676
(1) Dipstick
KiSC issued 01, 2006 A