Toro Z1-24OE02, Z1-24OE01 Service Manual
ONAN T260G ENGINE SERVICE MANUAL
Table of Contents – Page 1 of 2
SAFETY PRECAUT I O NS
GENERAL
PROTECT AGAINST MOVING PARTS
BATTERIES
FUEL SYSTEM
EXHAUST SYSTEM
EXHAUST GAS IS DEADLY!
COOLING SYSTEM
KEEP THE UNIT AND SURROUNDING AREA CLEAN
INTRODUCTION
EXHAUST GAS IS DEADLY!
GENERAL INFORMATION
INTRODUCTION
ENGINE MODEL REFERENCE
SPECIFICATIONS
DIMENSIONS AND CLEARANCES
ASSEMBLY TORQUES
ENGINE TROUBLESHOOTING
OIL SYSTEM
CRANKCASE OIL
OIL FILTER CHANGE
CRANKCASE BREAT HER
PRESSURE LUBRICAT IO N
FUEL SYSTEM
CARBURETOR
CARBURETOR OVERHAUL
PULSATING-DIAPHRAGM FUEL PUMP
AIR CLEANER
DASHPOT ADJUSTMENT
GOVERNOR ADJUSTMENT
IGNITION AND BATTERY CHARGING
BREAKER POINT IGNITION SYSTEM
IGNITION TIMING
ELECTRONIC IGNITION SYSTEM
IGNITION TIMING
BREAKER POINT AND ELECTRONIC IGNITION COILS
SPARK PLUGS
BATTERY INSPECTION
BATTERY JUMP STARTIN G
FLYWHEEL ALTERNAT OR
ALTERNATOR OUTPUT TEST
STARTING SYSTEM
ELECTRIC STARTER
ONAN T260G ENGINE SERVICE MANUAL
Table of Contents – Page 2 of 2
ENGINE DISASSEMBLY
DISASSEMBLY/ASSEMBLY
VALVE SYSTEM
TAPPETS
VALVE FACE AND SEAT GRINDING
FLYWHEEL
GEAR COVER
GOVERNOR CUP
TIMING GEARS
PISTONS AND CONNECTING RODS
CYLINDER BLOCK
CRANKSHAFT
BEARINGS
CRANKSHAFT ENDPLAY
CHECKING CONNECTING ROD BEARING CLEARANCE
OIL SEALS
PISTON ASSEMBLY
INSTALLATION OF PISTON IN CYLINDER
CYLINDER HEADS
CYLINDER HEAD STUD TEST AND REPLACEMENT PROCEDURE
ALIGNING BLOWER WHEEL, VENTURI AND CHAFF SCREEN
Service
Manual
Engine
Safety
It
is recommended that you read your engine manual and
become thoroughly acquainted with your equipment before
you start the engine.
Precautions
This symbol if used warns of imme-
diate hazards which will result in
severe personal injury or death.
WARNING
This symbol refers to a hazard or
unsafe practice which can result in
severe personal injury or death.
Fuel System
DO
NOT fill fuel tanks while engine is running.
DO
NOT smoke or use an open flame in the vicinity of the
engine or fuel tank. Internal combustion engine fuels are
highly flammable.
Fuel lines must be of steel piping, adequately secured,
and free from leaks. Piping at the engine should be
approved flexible line. Do not use copper piping for
flexible lines as copper will work harden and become
brittle enough
to
break.
CAUTION
personal injury or product or property damage.
Fuels, electrical equipment, batteries, exhaust gases and
moving parts present potential hazards that can result in
serious, personal injury. Take care in following these recommended procedures. All local, state and federal codes should
be consulted and complied with.
This symbol refers to a hazard or
unsafe practice which can result in
Exhaust System
This engine is not designed or in-
k!!!!!!!!!!!
tended for use in any type of aircraft,
Use of this engine in aircraft can result in engine failure
and causes serious personal injury or death.
Exhaust Gas is Deadly!
General
Provide appropriate fire extinguishers and install them in
convenient locations. Use an extinguisher rated ABC by
NFPA.
Make sure that all fasteners on the engine are secure and
accurately torqued. Keep guards in position over fans,
driving belts, etc.
If it is necessary to make adjustments while the engine is
running, use extreme caution when close to hot exhausts,
moving parts, etc.
Protect Against Moving Parts
Do
not wear loose clothing in the vicinity of moving parts,
such as PTO shafts, flywheels, blowers, couplings, fans,
belts, etc.
Exhaust gases contain carbon monoxide, a poisonous gas
that can cause unconsciousness and death. It is an odorless
and colorless gas formed during combustion of hydrocarbon
fuels. Symptoms of carbon monoxide poisoning are:
Dizziness Vomiting
Headache
Weakness and Sleepiness
If
you experience any of these symptoms, get out into fresh air
immediately, shut down the unit and do not use until
been inspected.
The best protection against carbon monoxide inhalation is
proper installation and regular, frequent inspections
complete exhaust system. If you notice a change in the sound
or appearance
immediately and have it inspected and repaired at once by a
competent mechanic.
Be sure all fuel supplies have a positive shutoff valve.
Exhaust products of any internal combustion engine are
toxic and can cause injury, or death
applications, especially those within a confined area,
should be equipped with an exhaust system to discharge
gases to the outside atmosphere.
Do not use exhaust gases to heat a compartment.
Make sure that your exhaust system is free of leaks.
Ensure that exhaust manifolds are secure and are not
warped by bolts unevenly torqued.
of
exhaust system, shut the unit down
if
inhaled.
Muscular Twitching
Throbbing in Temples
All
engine
it
has
of
the
Keep your hands away from moving parts.
Batteries
Before starting work on the engine, disconnect batteries
to
prevent inadvertent starting of the engine.
DO
NOT SMOKE while servicing batteries. Lead acid
off
batteries give
can be ignited by flame, electrical arcing or by smoking.
Verify battery polarity before connecting battery cables.
Connect negative cable last.
a highly explosive hydrogen gas which
Cooling System
Coolants under pressure have a higher boiling point than
water. DO NOT open a radiator pressure cap when
coolant temperature is above
engine is running.
Keep the Unit and Surrounding Area Clean
Make sure that oily rags are not left on or near the engine.
Remove all unnecessary grease and oil from the unit.
Accumulated grease and oil can cause overheating and
subsequent engine damage and present a potential fire
hazard.
212F
(100°C)
or while
E-6
Table' of Contents
TITLE
General Information
Speclflcations..
Dimensions and Clearances
Assembly Torques and Special Tools
Engine Troubleshooting
Oil System
Fuel System
Ignition and Battery Charging..
Starting System
Engine Disassembly
PAGE
. l-1
.2-1
.3-1
.4-1
.5-1
.6-1
.7-1
.8-1
.9-1
.10-1
WARNING]
EXHAUST GAS
Exhaust gases from all fuels (including diesel, gasoline, liquid propane, natural
gas) contain carbon monoxide, an odorless and colorless gas. Carbon monoxide
is poisonous and can cause unconsciousness and death. Symptoms of carbon
monoxide poisoning can include:
IS
DEADLY!
Dizziness
Nausea
Headache
Weakness and Sleepiness
IF
YOU
OR ANYONE ELSE EXPERIENCE
INTO THE FRESH AIR IMMEDIATELY. .If symptoms persist, seek medical
attention. Shut down the unit and do not operate until it has been inspected and
repaired.
Protection against carbon monoxide inhalation includes proper installation,
ventilation and regular, frequent visual and audible inspections
exhaust system.
Throbbing in Temples
Muscular Twitching
Vomiting
Inability to Think Coherently
ANY
OF
THESE SYMPTOMS, GET OUT
iii
of
the complete
General Information
INTRODUCTION
This manual deals with specific mechanical and electrical information needed by engine mechanics for
troubleshooting, servicing, repairing, or overhauling
the engine.
Use the table of contents for a quick reference to the
separate engine system sections.
Use the separate Parts Catalogs available at the
dealer level, for parts identification and for establish-
ing their proper location on assemblies.
The troubleshooting guide is provided as a quick
reference for locating and correcting engine trouble.
The illustrations and procedures presented in each
section apply to the engines listed on the cover. The
flywheel-blower end of the engine is the front end
right and left sides are determined by viewing the
engine from the front.
The disassembly section contains major overhaul
procedures for step by step removal, disassembly,
inspection, repair and assembly of the engine
components.
If a major repair or an overhaul is necessary, a competent mechanic should either do the job or supervise
and check the work of the mechanic assigned to do
the job to ensure that all dimensions, clearances and
torque values are within the specified tolerances.
The wiring diagram on the last page of the manual
shows how the electrical components are interconnected.
A parts catalog (availableat the dealer level) contains
detailed exploded views of each assembly and the
individual piece part numbers and their proper names
for ordering replacement parts.
so
Use only Genuine Onan replacement parts to ensure
quality and the best possible repair and overhaul
results. When ordering parts, always use the complete Model and Spec number as well as the Serial
number shown on the nameplate.
ENGINE MODEL REFERENCE
Identify your model by referring to the MODEL and
SPEC (specification) NO. as shown on the unit
name
plate
serial number when making reference to your engine.
How to interpret MODEL and SPEC
1.
Factory code for general identification of basic
engine series.
2.
Number of cylinders.
3.
Cubic inch displacement.
4.
Engine duty cycle.
5.
Fuel required (G=gasoline).
6.
Cooling system description
(A=air-cooling-pressure).
7.
BHP rating.
8.
Factory code for designated optional equipment,
if
any.
9.
Specification (spec letter) which advances with
factory production modifications.
Always use this number and the engine
NO
2 60G G
1234567
A
024
1
8 9
A
WARNING
INCORRECT SERVICE
PERSONAL INJURY AND/OR EQUIPMENT DAMAGE. SERVICE PERSONNEL
MUST BE QUALIFIED TO PERFORM ELECTRICAL AND/OR MECHANICAL
SERVICE.
OR
REPLACEMENT OF PARTS CAN RESULT IN SEVERE
1-1
I
Specifications
This manual contains
SPECIFICATION
Number of Cylinders
Bore
Stroke
Displacement
Compression Ratio
Rated Speed (Maximum) RPM
Power at BHP
Rated Speed
Oil Filter
Oil Capacity Without Qt
Filter (litre)
Oil Capacity With Qt
Filter Change (litre)
Crankshaft Rotation
(viewed from flywheel) Clockwise
Governor Variable Speed Mechanical
Valve Clearance (Cold)
Intake in
Exhaust in
Spark Plug Gap in
Breaker Point Gap Static (Spec A-E)
(Full
Separation and Engine Cold) (mm)
Ignition Timing
Cylinder Compression psi
SI
metric equivalents that
after the
U.S.
customary units
UNIT
MEASURE
follow
immediately in parentheses
of
measure.
OF
in
(mm)
in
(mm)
cu
in
(cm3)
SERIES
T-260G
3.56
(90.48)
3.0
(76)
60
(983)
7.0
3600
24
(kw)
(1 7.9)
Full
2.5
(2.4)
3.0
(2.8)
.005
(mm)
(0.1 3)
.013
(mm)
(0.33)
.025
(mm)
in
BTC
(0.64)
.020
(0.51)
20°
75
(kPa)__
51 7
2
to
Flow
to
115
to
1
793
2-1
Dimensions
All
clearances given at room temperature
parentheses) unless otherwise specified
DESCRIPTION MINIMUM MAXIMUM
CYLINDER
Cylinder Bore Honed Diameter
Maximum Allowable
Taper 0.003 (0.08)
Out-of-Round
Main Bearing Inside Diameter (Without bearing) 2.1 87
Main Bearing Inside Diameter (Installed)
Camshaft Bearing Bore (Bearing Installed)
Interference Stud Height from Top Surface of Block
Spec C, D, E
Top2 2.00 (50.80) (2.06 (52.32)
Middle 4 1.84 (46.74) 1.90 (48.26)
Bottom 4 1.16 (29.46) 1.22 (30.99)
CRANKSHAFT
Main Bearing Journal Diameter 1.9992 (50.78)
Main Bearing Clearance
Spec A-E
Begin Spec F
Connecting Rod Journal Diameter
Crankshaft End Play
CONNECTING
Large Bore Diameter (Without bearing installed
and rod bolts properly torqued
Connecting Rod Side Clearance
Piston Pin Bushing Bore (Without bearing)
Piston Pin Bushing Bore with Bearing,
(Finished bore)
Bearing
Aluminum Rod
Iron Rod
CAMSHAFT
Bearing Journal Diameter
Bearing Clearance
End Play
Spec A-E
Begin Spec F
Camshaft Lift
Intake
Begin Spec
Begin Spec E
Begin SpecF 0.305 (7.75)
Exhaust
Begin Spec
Begin Spec E
Begin SpecF 0.295 (7.49)
BLOCK
ROD
to
Crankshaft Clearance
A
A
and
of
70°F
(21
Clearances
C)
All
dimensions in inches (approximate miilimetre dimensions in
Inches
3.5625 (90.49) 3.5635 (90.51)
2.0015 (50.84) 2.0040 (50.90)
1.3760 (34.95) 1.3770 (34.98)
0.0025 (0.064) 0.0038 (0.097)
0.0024 (0.061) 0.0042 (0.107)
1.6252 (41.28) 1.6260 (41.30)
0.005
1.7505 (44.46) 1.7510 (44.48)
0.0020 (0.051) 0.0160 (0.406)
0.8115 (20.61) 0.8125 (20.64)
0.7504 (19.06) 0.7508 (19.07)
0.0020 (0.051) 0.0033 (0.084)
0.0020 (0.051) 0.0033 (0.084)
1.3740 (34.90) 1.3745 (34.91)
0.0015
0.0030 (0.076) 0.0120 (0.305)
0.011 (0.28) 0.048 (1.22)
0.286 (7.26) 0.294 (7.47)
0.285 (7.24) 0.293 (7.44)
0.291 (7.39) 0.299 (7.59)
0.283 (7.19) 0.291 (7.39)
(mm)
(55.55)
(0.13)
(0.038) 0.0030 (0.076)
Inches (mm)
0.003 (0.08)
(2.188 (55.58)
2.0000
0.009 (0.23)
(50.80)
DESCRIPTION
PISTON
Clearance in Cylinder
Measure
Piston Pin Bore..
Ring Groove Width
Top
No.
No.
PISTON PIN
Clearance in Piston
Clearance in Connecting
Aluminum Rod
Iron Rod
Diameter.
-PISTON RINGS
Clearance
Top Groove
Ring End Gap in Cylinder
INTAKE VALVE
Stem Diameter
Clearance (Stem to Guide)
Valve Face Angle
tNTAKE VALVE SEAT
Seat Cylinder Head Bore Diameter..
Seat Outside Diameter
Valve Seat Width
Valve Seat Angle
EXHAUST VALVE
Stem Diameter
Clearance (Stem to Guide)
Valve Face Angle
EXHAUST VALVE SEAT
Seat Cylinder Head Bore Diameter..
Seat Outside Diameter
Valve Seat Width
Valve Seat Angle
VALVE GUIDE
Inside
TAPPET
Body Diameter
Bore Diameter..
Clearancein Bore
VALVE SPRINGS INTAKE AND EXHAUST
Valve Spring Free Length (Approx.)
Valve Spring Length
Valve Open..
Valve Closed
Spring Load
Spring Load
1.187
Below Top of Piston and
. . . . . . . . . . . . . .
1
Compression Ring
2
Compression Ring..
3
Oil Control Ring
. . .
.
.
.
. .
. .
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Diameter
. . . . . . . . . .
.
.
.
. .
. . . . . . .
.
. . . . . . .
@
1.375
inch (Valve Closed).
@
1.125
inch (Valve Open)
90"
.
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.
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Rod
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from pin
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Inches
0.0070
0.7502
.
0.080
0.080
0.188
0.0001 (0.003)
0.0002
0.0002
.
0.7500
0.002
0.010
.
0.3425
0.0010
.
1.5645
1.5690
0.031
.
.
0.3410
0.0025
1.2510
1.2550
.
0.031
.
.
0.344
0.7475
0.7500
0.0015
38
71
MINIMUM
(mm)
(19.055)
Ib.
Ib
(17
(32
MAXIMUM
Inches
kg)
kg)
0.0090
0.7506
0.081
0.081
0.189
0.0005
0.0008
0.0008
0.7502
0.008
0.020
440
1.5655
1.5700
0.047
45O
0.040
440
1.2520
.1.2560
0.047
45O
0.7480
0.7515
0.003
(28.58)
(34.93)
42
79
(0.1 78)
(2.032)
(2.032)
(4.775)
(0.005)
(0.005)
(1
9.05)
(0.051)
(0.254)
(8.70) 0.3430
(0.025) 0.0025
(39.74)
(39.85)
(0.787)
(8.661) 0.3420
(0.064)
(31.78)
(31.88)
(0.787)
(8.74) 0.346
(1
8.99)
(1
9.05)
(0.038)
1.662 (42.21)
1.125
1.375
(0.229)
(19.065)
(2.057)
(2.057)
(4.801)
(0.01 3)
(0.020)
(0.020)
(19.06)
(0.203)
(0.508)
(0.064)
(39.76)
(39.88)
(1.194)
(8.687)
(0.1 01)
(31.80)
(31.90)
(1.194)
(1
(1 9.09)
(0.076)
Ib.
Ib
(mm)
(8.71)
(8.79)
9.00)
3-2
DESCRIPTION
GEAR BACKLASH
Timing Gear
Spec
A-E
Begin Spec
F
Oil Pump Gear
spec
A-E
Begin Spec
F
GOVERNOR
Dashpot to Governor Arm Bracket..
MINIMUM
Inches
0.002
0.001
0.002
0.001
0.040
(mm)
(0.051)
(0.025)
(0.051)
'(0.025)
(1.02)
MAXIMUM
Inches
0.003
0.005
0.005
0.008
0.060
(mm)
(0.076)
(0.127)
(0.127)
(0.203)
(1.52)
3- 3
Assembly
The torque values given in Table 1 have been deter- Check all studs, nuts, and capscrews, and tighten as
mined for the specific applications. Standard torque required to keep them from working loose. Refer to the
values must not be used where those listed in Table
apply. The engine assembly torques given here will capscrews.
assure proper tightness without danger
threads.
new engine oil before torquing.
All
threads must be clean and lubricated with
Torques
1
of
stripping
PARTS MANUAL
for the location
of
washers and
DESCRIPTION
Cylinder Head Nuts (with
Compression Washers)
SpecA-E
Begin Spec F
Cylinder Head Nuts (without
Compression Washers)
SpecA-E
Begin Spec F
Rear Bearing Plate
Connecting Rod Bolt
SpecA-E
Begin Spec F
Flywheel Capscrew.
Starting Mounting Bracket
to Oil Base Screws.
TABLE
TORQUE
SPECIFICATION DESCRIPTION
F1.-Lb. Nm
11-13 (15-18) Intake Manifold Mounting
14
14-16 (19-22) Screws
17
25-28 (34-38) Begin Spec F
14-16 (1 9-22)
27-29 (37-39)
50-55 (67-75)
24-26 (33-35) Nuts.
(19) Screws
(23) Spec
1.
Gear Case Cover.
Oil Pump.
Valve Cover.
Exhaust Manifold Mounting
A-E
Other 1/4” /4" Cylinder Block Studs
and Nuts
Other 5/16" Cylinder Block
Studs and Nuts
Other 3/8” Cylinder Block
TORQUE
SPECIFICATION
F1.-Lb. Nm
8-10 (1 1-14)
7-9 (10-1 2)
4-8
20-23
9-11
7-9 (10-72)
8-10 (1 1-13)
18-23 (24-31)
(27-31)
(
5-11)
(27-31)
(12-15)
Special
The following special tools are available from
Onan. For further information see
Tools
TOOL CATALOG
900-0019.
Valve Seat Driver
Valve Guide Driver
Oil Guide and Driver
Combination Bearing Remover (Main and Cam)
Combination Bearing Driver (Main and Cam)
Flywheel Puller
4-1
Engine
Troubleshooting
I
IGNITION SYSTEM
FUEL SYSTEM
INTERNAL ENGINE
COOLING SYSTEM (AIR COOLED)
5-1
THROTTLE AND GOVERNOR
M-1686-1
Oil
System
CRANKCASE OIL
Refer to engine nameplate or Periodic Maintenance
Schedule, located
change interval. If operating in extremely dusty, high
ambient, or low ambient conditions change oil more
often.
Run engine until thoroughly warm before draining oil.
Stop the engine, place a pan under the drain outlet and
remove the oil drain plug or open the drain valve. After
the oil is completely drained, replace the drain plug or
close the drain valve. Refill with oil of the correct API
classification and appropriate SAE viscosity grade for
the temperature conditions.
Oil must meet or exceed the API designation SF, SF/CC
or SF/CD. Refer to the chart to determine the proper
viscosity grade of oil to use. Straight weight oils are
recommended for severe duty use and at temperatures
above
32"
F (0°C) for minimum oil consumption.
in
the Operator's Manual, for oil
Oil
level should be to the
engine and run for a short time to check for oil leaks
around the drain plug.
FULL
mark of the dipstick. Start
WARNING
check oil while the engine is operating.
fingers and hands clear when removing the oil drain
plug and wear protective clothing.
CAUTION
tures and
Crankcase pressure can blow out hot
oil and cause serious burns.
Hot crankcase oil can cause burns if
it is spilled or splashed on skin. Keep
ALWAYS REPLACE
FIGURE
may
1.
Do
causes higher operating tempera-
cause foaming.
TIGHTLY
LEAKAGE MAY
CRANKCASE OIL
not overfill crankcase. Excess oil
OR
OCCUR
FILL
Do
OIL
NOT
LS-1170
I
FILTER
COOLING
FILTER
FINS
2.
OIL
FILTER
OIL FILTER CHANGE
Refer to engine nameplate or Periodic Maintenance
Schedule, located in the Operator's Manual, for oil filter
change interval. If operating in extremely dusty, high
ambient, or low ambient conditions change oil more
often.
Spin
off
oil filter element and discard it. Thoroughly
clean filter mounting surface and make sure new gasket
is inserted in the element.
6-1
Apply a thin film of oil to the gasket. Spin element down
by hand until gasket just touches mounting pad and
then turn down an additional
1/2-3/4
turn.
Do
not
overtighten.
With oil in crankcase, start engine and check for leaks
around filter element. Retighten only as much as
necessary to eliminate leaks; do not overtighten.
Clean or replace crankcase breather baffle periodically.
Be sure baffle material-doesn’t come apart and work into
the manifold.
To disassemble, remove breather hose from cap and
valve assembly. Remove cap and valve assembly and
wash in a suitable solvent. Replace cap and valve if balls
do not move freely. Pull baffle out and wash in solvent.
To
allow free operation of the valve, screens must be
positioned as shown in Figure
3.
CRANKCASE BREATHER
The crankcase breather prevents pressure from
building up in the crankcase. It also prevents oil
contamination by removing moisture or gasoline
vapors and other harmful blow-by materials from the
crankcase. Thesevapors are routed to the carburetor
where they are mixed with incoming air and burned in
the combustion chamber.
cause leaks, high oil consumption, rough idle,
reduced engine power and a rapid formation of
sludge and varnish within the engine.
Crankcase Breather Service
This engine uses. a crankcase breather valve for
maintaining crankcase vacuum. If the crankcase
becomes pressurized as evidenced by oil leaks at the
seals, clean baffle and valve in a suitable solvent.
A
sticky breather valve can
PRESSURE LUBRICATION
All
engines use an oil pump to provide a constant flow
of oil to the engine parts. The oil supply collects in the
oil base where it is picked up by the oil pump pick-up
cup.
A
by-pass valve is used to control oil pressure.
Drain oil before removing oil base and always use a
new gasket when replacing the oil base.
Oil
Pump
The oil pump (Figure
cover and is driven by the crankshaft gear. Inlet pipe and
screen assembly are attached directly to the pump
body. A discharge passage in pump cover registers with
a drilled passage in the crankcase. Parallel passages
distribute oil to the front main bearing, rear main
bearing, and pressure control bypass valve.
4)
is mounted behind the gear
OIL
PUMP PICK-UP CUP
CAP AND VALVE
FIGURE
3.
BREATHER
HOSE
CRANKCASE BREATHER
HOSE
CLAMP
OIL PUMP ASSEMBLY
6-2
CRANKCASETURNED
ON LEFT SIDE
FIGURE
4.
OIL
PUMP
LS-1109
ASSEMBLY
Circumferential grooves in the main bearings supply
oil to connecting rod bearings through drilled pas-
-.,sages from each main journal.
\connects the front main bearing oil supply to
'camshaft bearing; rear cam bearing
ted. Oil overflow from the bypass valve provides
lubrication to the camshaft drive gears.
Normal oil pressure should be
higherwhen the engine is at normal operating temperature.
If
pressure drops below this value at governed
speed, inspect oil system for faulty components.
A
drilled passage
is
splash lubrica-
30
psi
(207
the
front
kPa) or
The valve is non-adjustable and normally does not
need maintenance. Determine
normally by inspecting plunger action as follows:
1.
Remove the
behind gear cover and under governor arm.
2.
Remove spring and plunger with a magnet tool.
3.
Determine proper valve operation by checking
the spring and plunger according to the following
measurements.
3/8 x 24 x 7/8
if
valve is operating
cap screw located
Check oil pump thoroughly for worn parts. Oil pump
to prime it before reinstalling. Except for gaskets and
pick-up cup, component parts of the pump are not
available individually. Install a new pump assembly
any parts are worn.
Oil
By-Pass
The by-pass valve (located to the right and. behind gear
cover, Figure
excess oil to flow directly back to the crankcase.
Normally the valve begins to open about
(138
kPa).
Valve
5)
controls oil pressure by allowing
20
if
psi
Plunger Diameter..
Spring
Free Length..
Load
when compressed to
4.
Check the valve seat and clean away any accumulation of metal particles which could cause erratic
valve action. Verify that the valve seat is not damaged.
5.
Clean plungerand spring in parts cleaning solvent
and install.
0.3105
1.00
2.6Ifr0.2
0.5
to
(7.89
inch
Ibs.
(11.6+0.9N)
inch
0.3125
to
7.94
(25.4
(12.7
mm)
mm)
mm)
in.
FIGURE 5.
BY-PASS VALVE
6-3
Fuel
System
CARBURETOR
Set the adjustment screw about
(rich) from the midpoint
of
this range. On Nikki
1/8
turn outward
The carburetor mixture screw settings were set for carburetors the idle adjustment is limited
maximum efficiency at the factory and should normally turn. Do not go beyond these limits.
not be disturbed.
If
adjustments seem necessary, first be
sure the ignition system is working properly and
governor sensitivity is properly adjusted.
If
adjustment is needed, refer to Figures 1 and 2 and
proceed as follows:
CAUTION
and seat.
1.
Turn
Walbro mixture screw settings:
Forcing the mixture adjustment
screw tight will damage the needle
in only until light tension can be felt.
THROTTLE
Turn both mixture screws in until lightly seated
l),
(Figure
then back the idle mixture screw out
turn and the main mixture screw out 1-3/4 turns.
Nikki
limited idle adjustment mixture screw
1/2
NlKKl
CARBURETOR
AND
LIMITED
IDLE
WITH
SEMI-AUTOMATIC
MIXTURE
SCREW.
CHOKE
settings:
The carburetor has a limited idle adjustment range
between stops
be adjusted within these limits; in
1/8
turn. The screw should only
to
lean the
mixture, out to richen. There is no main mixture
adjustment.
MAIN FUEL
ADJUSTMENT
When replacing the idle mixture screw, turn in until
lightly seated, then back screw out
Replace limiter cap
so
the tab is approximately
1-1/2
turns.
IDLE FUEL
ADJUSTMENT
centered.
2.
Start the engine and allow it
10
(at least
minutes).
to
warm up thoroughly
FIGURE
WALBRO
1.
CARBURETOR
CARBURETOR ADJUSTMENT
Some equipment manufacturers may require higher
throttle stop speed and governor low speed rpm
settings. Refer
to
equipment manufacturer’s Opera-
tor’s Manual for the correct rpm settings. When rpm
5.
Readjust the throttle screw for
1000
adjust the governor low speed screw for
idle.
rpm idle, then
settings are not specified by the equipment manufacturer use the rpm settings listed in Steps 3 and
5.
6.
Move the engine speed control to the fast position.
Bend the high speed stop on the governor
3.
Move the engine speed control to the slow position.
Back out the low speed screw on the governor
so
engine runs at the vehicle manufacturer’s recommended speed (Figure
2.)
the throttle stop screw on the carburetor controls
engine speed (Figure
screw for
4.
Determine the best idle mixture setting by first
1000
rpm idle.
turning the idle adjustment screw in until engine
speed drops and then outward until engine speed
drops again. Over a narrow range between these
two settings, engine speed remains at its highest.
2).
Adjust the throttle stop
7.
Check the main mixture adjustment (Walbro carburetors only) by rapidly accelerating the engine
from idle
evenly and without hesitation.
main adjustment screw out in
to
full speed. The engine should accelerate
If
it does not, turn the
1/8
turn increments
until the engine accelerates smoothly, but do not
turn it out more than
1/2
turn beyond the original
setting.
to
FS-1406-2
1100
so
1/8
FS-1002
rpm
the
7-1
HIGH
SPEED
THROTTLE
SCREW
STOP
In general, overhauling a carburetor consists of dis-
assembly,
a
thorough cleaning, and replacement
of
worn parts. Carburetor repair parts are available.
General instructions for overhauling a carburetor are
given below. Carefully note the position of all parts
while removing to assure correct placement when
reassembling Read through all the instructions before
beginning for a better understanding of the pro-
cedures involved. Carburetor components are shown
in Figure
3.
GOVERNOR
GOVERNOR
FRONT PULL GOVERNOR
THROTTLE
THROTTLE
GOVERNOR
SPRING
SCREW
STOP
PLATE
CONTROL\
GOVERNOR
WARNING
explosion.
Ignition of fuel can cause serious
personal injury or death by fire or
Do
not permit any flame, cigarette, or other
igniter near the fuel system.
I
ARM
FS-1119
CHOKE
PLATE
NIKKI
CARBURETOR
FLOAT
ASSEMBLY
ADJUSTMENT
IDLE
FS-1440-3
STOP
ADJUSTMENT
SIDE
PULL
GOVERNOR
FIGURE
2.
GOVERNOR SPEED ADJUSTMENT
CARBURETOROVERHAUL
Carburetion problems that are not corrected by
mixture adjustments are usually a result of gummedup fuel passages or worn internal parts. The most
effective solution is a carburetor overhaul.
WALBRO CARBURETOR
FIGURE
3.
CARBURETOR ASSEMBLY
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