Tecumseh VLV Technician's Handbook
TECUMSEH
VLV
ENGINES
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T E C H N I C I A N ' S H A N D B O O K
This manual covers VLV40 - 675.
Other illustrated Tecumseh 2-Cycle Engine, 4-Cycle Engine
and Transmission manuals; booklets; and wall charts are
available through Tecumseh.
For complete listing write or call
(VECTOR)
4-CYCLE
TABLE OF CONTENTS
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Chapter 1 General Information .............................................................................. 1
Engine Identification ........................................................................................... 1
Engine Breakdown .............................................................................................. 2
Parts List ............................................................................................................. 3
Engine Care ........................................................................................................ 4
Fuel, Oils, Storage .............................................................................................. 4
Tune-Up Procedure ............................................................................................ 5
4-Cycle Engine Theory ....................................................................................... 6
Chapter 2
Air Cleaners ..................................................................................................... 7-8
Carburetion ......................................................................................................... 9
Identification ........................................................................................................ 9
Parts Breakdown................................................................................................. 9
Float Bowl Service ............................................................................................ 10
Float Bowl Reassembly .................................................................................... 11
Float Bowl Drain........................................................................................... 10-11
Rebuilding the carburetor body ......................................................................... 11
Welch Plug Removal ........................................................................................ 11
Cleaning Welch Plug and Installation ............................................................... 11
Throttle Shaft & Shutter .................................................................................... 12
Primer Bulb ....................................................................................................... 12
Chapter 3
Governors and Linkage ............................................................................... 13-14
Chapter 4
Starters ............................................................................................................. 15
Rewind Starter ............................................................................................. 15-16
12 Volts Starters .......................................................................................... 17-18
Chapter 5
Flywheels and Servicing ................................................................................... 19
Removal and Assembly ............................................................................... 19-20
Brake System Operation ................................................................................... 20
Wiring ................................................................................................................ 21
Battery .............................................................................................................. 21
Replace Brake Pad ........................................................................................... 21
Brake Mechanism Installation ........................................................................... 22
Control Switch & Replacement ......................................................................... 22
Chapter 6
Alternator .......................................................................................................... 23
Troubleshooting Electric Start Engines ............................................................. 23
Chapter 7
Ignition System ................................................................................................. 24
Ignition System Operation ................................................................................. 24
Spark Plug Service ........................................................................................... 23
Timing Adjustment ............................................................................................ 24
Chapter 8
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Piston, Rings and Connecting Rod ................................................................... 25
Piston ................................................................................................................ 25
Rings ................................................................................................................. 25
Chapter 9
Cylinder and Cylinder Head Service ................................................................. 26
Reboring ........................................................................................................... 26
Cylinder Head ................................................................................................... 26
Chapter 10
Crankshaft, Camshaft and Lubrication.............................................................. 27
Crankshaft Timing Mark .................................................................................... 27
Camshaft Timing Mark ...................................................................................... 27
Compression Release....................................................................................... 27
Lubrication System Operation........................................................................... 28
Crankcase Breather Operation .................................................................... 28-29
Chapter 11
Valves, Lifters, Springs and Seats .................................................................... 30
Valve Removal .................................................................................................. 30
Valve Seats ....................................................................................................... 30
Valve Service .................................................................................................... 30
Valve Installation ............................................................................................... 31
Lifters ................................................................................................................ 31
Oversize Guides ............................................................................................... 31
Chapter 12
Removing the Mounting Flange ........................................................................ 32
Oil Seal Service ................................................................................................ 32
Mounting Flange Installation ............................................................................. 32
Chapter 13
Troubleshooting ........................................................................................... 33-39
Chapter 14
Engine Specifications ....................................................................................... 40
Torque Specifications ....................................................................................... 41
Chapter 15
Training Aids and Tools .................................................................................... 42
Chapter 16
Sears Craftsman Cross Reference ................................................................... 45
Tecumseh Products Company
C 1996
Chapter 1
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GENERAL INFORMATION
ENGINE IDENTIFICATION
Tecumseh engine model, specification and serial
numbers are stamped or decaled on the blower housing.
The decal also contains any emission compliance
information.
The letters which precede the model numbers indicate
the basic type of engine:
VLV - Vector Lightweight Vertical
The numbers which follow engine type letters indicate
the basic engine horsepower:
40 - 4.0 Horsepower
50 - 5.0 Horsepower
Following the engine size numbers are the engine
specifications numbers.
The specification number is used when identifying
engine parts example 502012A.
The serial number is the production date code.
7040 - serial number (example)
7 - Year in decade of manufacture (1997)
40 - The last 3 digits of date code represent the
calendar (the 40th day of 1997)
D - represents the shift and line on which the
engine was built at the factory.
VLV60-502012A
VLV60-502012A (D)
6215C
Emissionized engines that meet the California Air
Resource Board (C.A.R.B.) or the Environmental
Protection Agency (E.P.A.) standards will include
additional required engine information on the engine
decal.
NOTE: To maintain best possible emission
performance, use only Genuine Tecumseh Parts.
SHORT BLOCKS. New short blocks are identified by a
tag marked SBH (Short Block Horizontal) or SBV (Short
Block Vertical). These tags are used to properly identify
the correct parts if service is required. They are attached
to either the sump bolts or valve box cover.
THIS ENGINE MEETS 1995-1998
CALIF. EMISSION REGULATIONS FOR
ULGE ENGINES AS APPLICABLE
FUEL: REGULAR UNLEADED OIL: USE SAE 30
VLV60-502012A (D)
RTP358UIG2RA
207cc
6215C
1
NOTE: On newer VLV models the breather
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tube will be a straight hose.
OPTIONAL
PRE-FILTER
MODEL and SERIAL
NUMBERS HERE
PARTS IDENTIFICATION
This is a parts breakdown of a typical VLV engine. Use this parts
breakdown to identify parts. When ordering parts always refer to the
engine model and specification number stamped on the engine blower
housing.
Carburetor and starter breakdowns are found in the chapters referring
to their repair.
2
SBV-XXX
SER-XXX
NOTE: If the short block has been
replaced, an identification tag for service
parts is located on the valve box cover.
Ref.
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No. Part Name
1 Cylinder Assy.
2 Pin, Dowel
3 Element, Breather
4 Cover, Breather
5 Gasket, Breather cover
6 Screw, Thread forming, 10-24 x 1/2
7 Body, Breather valve
8 Valve, Breather check
9 Breather, Tube
10 Washer, Flat
11 Rod, Governor
12 Lever, Governor
13 Clamp, Governor lever
14 Screw, 8-32 x 5/16
15 Spring, Governor extension
16 Seal, Oil
17 Baffle, Blower housing (Incl. No. 195)
18 Screw, 1/4-20 x 5/8
19 Crankshaft Assy.
20 Piston & Pin Assy.
21 Ring Set, Piston
22 Ring, Piston pin retaining
23 Rod Assy., Connecting
24 Bolt, Connecting rod
25 Lifter, Valve
26 Camshaft Assy.
27 Pump Assy., Oil
28 Gasket, Mounting flange
29 Flange, Mounting
30 Plug, Oil drain
31 Seal, Oil
32 Washer, Flat
33 Gear Assy., Governor
34 Spool, Governor
35 Ring, Retaining
36 Gear, Idler
37 Screw, 1/4-20 x 1-9/16
38 Key, Flywheel
39 Flywheel
40 Fan, Flywheel
41 Washer, Belleville
42 Nut, Flywheel
43 Solid State Assy.
44 Cover, Spark plug
45 Screw, 10-24 x 1
46 Wire Assy., Ground
47 Gasket, Cylinder head
48 Head, Cylinder
49 Valve, Exhaust
50 Valve, Intake
51 Screw, 5/16-18 x 1-1/2
52 Spark Plug (Champion RJ-19LM or equivalent)
53 Spring, Valve
Ref.
No. Part Name
54 Cap, Valve spring
55 Gasket, Valve cover
56 Cover, Valve spring box
57 Screw, 10-24 x 1/2
58 Stud, Carburetor mounting
59 Link, Governor
60 Spacer, Carburetor mounting gasket
61 Lever Assy., Brake
62 Lever, Brake control
63 Link, Brake control lever
64 Spring, Brake
65 Ring, Retaining
66 Terminal
67 Spring, Brake control lever
68 Bushing, Brake control leer & brake lever
69 Spring, Compression
70 Spring, Compression
71 Screw, 5-40 x 7/16
72 Screw, 6-32 x 21/32
73 Gasket, Carburetor to air cleaner
74 Body, Air cleaner (Incl. Nos. 239, 299 & 350)
75 Screw, 10-32 x 2-3/32
76 Filter, Air cleaner (Paper)
77 Cover, Air cleaner
78 Nut, Lock, 1/4-20
79 Screw, 1/4-20 x 11/16
80 Plate, Control Assy., cover
81 Screw, 8-32 x 1/2
82 Housing, Blower
83 Screw, 1/4-20 x 1/2
84 Ring, Starter
85 Muffler
86 Plate, Muffler locking
87 Screw, 5/16-18 x 2-11/32
88 Cup, Starter
89 Screw, 8-32 x 21/64
90 Line, Fuel
91 Clamp, Fuel line
92 Clip, "U" Type Nut, 10-32
93 Tank Assy., Fuel
94 Cap, Fuel
95 Tube, Oil fill
96 "O" Ring
97 Clip, Fill tube
98 Dipstick, Oil
99 Plug, Starter
100 Screw, 10-32 x 35/64
101 Primer
102 Decal, Instruction
103 Decal, Primer
104 Carburetor
105 Starter, Rewind
3
ENGINE CARE
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FUELS. Tecumseh Products Company strongly
recommends the use of fresh, clean, UNLEADED
regular gasoline in all Tecumseh engines. Unleaded
gasoline burns cleaner, extends engine life and
promotes good starting by reducing the build-up of
combustion chamber deposits. Gasoline, gasohol
containing no more than 10% ethanol, 15% M.T.B.E. or
ETBE, leaded fuel can be used if regular unleaded is
not available.
STORAGE
NEVER STORE ENGINE WITH FUEL IN TANK
INDOORS OR IN ENCLOSED, POORLY
VENTILATED ENCLOSURES, WHERE FUEL
FUMES MAY REACH AN OPEN FLAME, SPARK
OR PILOT LIGHT AS ON A FURNACE, WATER
HEATER, CLOTHES DRYER OR OTHER GAS
APPLIANCE.
If engine is to be unused for 30 days or more, prepare
as follows:
Never use gasoline containing METHANOL, gasohol
containing more than 10% ethanol, gasoline additives,
or white gas because engine/fuel system damage could
result. If engine is to be unused for 30 days or more see
“STORAGE” instructions.
ENGINE OIL:
USE A CLEAN, HIGH QUALITY DETERGENT OIL. Be
sure original container is marked: A.P.I. service “SF” or
“SG”.
DO NOT USE SAE 10W40 OIL.
FOR SUMMER (ABOVE 32oF) USE SAE 30 OIL.
Using multigrade oil may increase oil consumption.
FOR WINTER (BELOW 32oF) USE SAE 5W30 OIL.
(SAE 10W is an acceptable substitute.)
(BELOW 0oF ONLY): SAE 0W30 is an acceptable
substitute.
OIL CHANGE INTERVALS. Change oil after first two
(2) hours of operation and every 25 hours thereafter, or
more often if operated under dusty or dirty conditions.
OIL CHECK. Check oil every 5 hours or each time the
equipment is used. Position equipment so the engine is
level when checking the oil.
DRAIN INTO APPROVED CONTAINER
OUTDOORS, AWAY FROM OPEN FLAME.
1. DRAIN FUEL SYSTEM:
Remove all gasoline from carburetor and fuel tank
to prevent gum deposits from forming on these parts
and causing possible malfunction of engine.
NOTE: VLV engines are equipped with a bowl drain
screw. See Chapter 2 for removal procedure.
A. Run engine until fuel tank is empty and engine
stops due to lack of fuel.
B. Disconnect fuel line at carburetor or fuel tank.
Be very careful not to damage fuel line, fittings
or fuel tank.
Drain any remaining fuel from system. Properly
reconnect the fuel line.
NOTE: If gasohol has been used, complete
preceding instructions “A” and “B” and then put
a small amount of unleaded (or leaded regular)
gasoline into fuel tank and repeat preceding
instructions “A” and “B”.
NOTE: Fuel stabilizer (such as STA-BIL) is an
acceptable alternative in minimizing the
formation of fuel gum deposits during storage.
Add stabilizer to gasoline in fuel tank or storage
container. Always follow mix ratio found on
stabilizer container. Run engine at least 10
minutes after adding stabilizer to allow it to reach
carburetor.
2. If oil has not been changed recently, this may be a
3. Remove spark plug and put 1/2 oz. (15 ml) of clean
4. Clean engine by removing any clippings, dirt, or
4
good time to do it. See “CHANGE OIL” instructions
in “MAINTENANCE” section of the Owner’s Manual.
engine oil into spark plug hole. Crank engine over,
slowly, several times.
AVOID SPRAY FROM SPARK PLUG HOLE
WHEN CRANKING ENGINE OVER SLOWLY.
Reinstall spark plug.
chaff from exterior of engine.
TUNE-UP PROCEDURE
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CAUTION: Remove spark plug wire before
doing any service work on engine.
1. Service or replace air cleaner as necessary. (See
Chapter 2 Air Cleaners)
2. Inspect level and condition of oil, change or add oil
as required.
3. Remove blower housing, clean all dirt, grass or
debris from intake screen, head and cylinder cooling
fins and carburetor governor levers and linkage.
4. Make sure fuel tank, fuel filters and fuel lines are
clean. Replace any worn or damaged governor
springs or linkage. Make proper governor
adjustments where required. (See Chapter 3)
NOTE: If the engine is equipped with a Tecumseh
fuel tank, an integral filter is molded inside.
STANDARD
PLUG
9. Run engine and allow it to warm up for 5 minutes.
After the engine is warm, set the engine governed
RPM to specifications. This information is located
only on Micro Fiche Card 30 or the Plus One and
Parts Smart computer look-up systems.
5. Replace the spark plug with the proper spark plug.
Consult the parts breakdown for the spark plug to
be used in the engine being serviced. The spark
plug air gap is .030'’. Install spark plug in engine
and tighten to 15 foot pounds torque. If a torque
wrench isn’t available, screw spark plug in as far as
possible, by hand, and use a spark plug wrench to
turn spark plug 1/8 to 1/4 turn further when reusing
spark plug, or 1/2 turn further if using a new spark
plug.
6. Make sure all ignition wires are free of abrasions,
breaks and are properly routed so they will not rub
on flywheel.
7. Properly reinstall the blower housing, gas tank, and
fuel lines, then properly check for spark as stated in
the ignition section of this manual.
8. Make sure all cables are adjusted for proper
operation.
5
4-CYCLE ENGINE THEORY
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Tecumseh four-cycle engines require four strokes or
cycles to complete one power cycle.
1. INTAKE. Intake valve is open, exhaust valve is closed.
Piston is traveling downward creating a suction action,
drawing the fuel-air mixture from the carburetor into the
cylinder area above the piston.
1. INTAKE
2. COMPRESSION. As the piston reaches Bottom Dead
Center, the INTAKE valve closes. The piston then rises,
compressing the fuel and air mixture trapped in the
combustion chamber, because both valves are closed.
3. POWER. Both valves remain closed. As the piston
reaches the Before Top Dead Center (BTDC) ignition
point, the spark plug fires, igniting the fuel-air mixture.
In the time it takes to ignite all the available fuel, the
piston has moved to TDC (Top Dead Center), ready to
take the full combustive force of the fuel for maximum
power and piston downward travel. The expanding
gases force the piston down.
3. POWER
4. EXHAUST. Exhaust valve opens. As the piston starts
to the top of the cylinder, the exhaust gases are forced
out.
After the piston reaches Top Dead Center (TDC), the
four cycle process will begin again as the piston moves
downward and the intake valve opens.
2. COMPRESSION
NOTE: Some emission compliance engines may use a
RCR (Ramp Compression Relief) system. This system
opens the intake valve during the compression stroke
allowing a small amount of the intake charge back down
the intake pipe. This eliminates unburned fuel going out
the exhaust during normal compression relief cycle
typically used on the exhaust valve.
6
4. EXHAUST
Chapter 2
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AIR CLEANERS
CAUTION: Before removing air cleaner, make sure ALL
excess dirt is removed from around it.
NOTE: If the engine is equipped with an optional poly
pre-filter always remove it first, to prevent dirt falling into
the filter body.
Air cleaners must be serviced frequently, to prevent dust
and dirt from entering the engine. Dust mixed with the
engine oil forms an extremely abrasive compound which
quickly wears out an engine.
A clogged air cleaner will affect engine performance.
Replacing a restricted (clogged) air filter should restore
engine performance.
AIR CLEANER SERVICE. The engine utilizes a treated
paper element with a foam rubber-like sealing edge.
The seal must fit properly to prevent dirt ingestion.
Replace air filter once a year or more often in extremely
dusty or dirty conditions.
DO NOT ATTEMPT TO CLEAN OR OIL THE PAPER
FILTER.
Be sure to clean base and cover thoroughly before
installing new paper filter.
POLYURETHANE-TYPE PRE-FILTERS. These
serviceable air filters utilize a polyurethane element
which will clog up with use. The element should be
cleaned and serviced in the following manner.
Wash element in a detergent and water solution and
squeeze (don’t twist) until all dirt is removed. Rinse
thoroughly.
Wrap in a clean cloth and squeeze (don’t twist) until
completely dry.
Re-oil element by applying a generous quantity of oil to
all sides. Squeeze vigorously to distribute oil and to
remove excess oil.
Clean air cleaner housing and cover. Dry thoroughly.
Reinstall pre-cleaner in air filter body.
SOME VECTORS ARE
EQUIPPED WITH BOLT
ACCESS HOLE & A PLUG.
REPLACE IF REMOVED.
POLY
PRE-FILTER
NEVER RUN THE ENGINE WITHOUT THE
COMPLETE AIR CLEANER INSTALLED ON THE
ENGINE.
NOTE: Serious damage to the engine may result
from using any other but the specified part number
filter. Use factory recommended parts only.
Some models use a dual stage air cleaner. This air
cleaner uses a polyurethane-type foam pre-filter along
with the paper element.
PLUG
BODY
PAPER
FILTER
7
TO SERVICE AIR CLEANER
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1. Loosen cover screw (A).
A
2. Swing cover down and remove from hinge (B).
3. Pull foam pre-filter out of air cleaner body (if
equipped with pre-filter).
4. Pull air filter out of air cleaner body.
5. Clean air cleaner cover and body.
6. Install a new paper filter (part no. 36046) (C).
7. Clean and install pre-filter (if so equipped).
8. Reinstall cover to air cleaner body.
Be sure hinge is assembled properly.
9. Swing cover up and tighten cover screw. (Do not
over tighten).
PRE-FILTER
B
C
8
CARBURETION
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Proper Carburetion Function is dependent on clean fresh
fuel and a well maintained air cleaner system. Most
causes of carburetion problems are directly related to
stale fuel and dirt ingestion. Inspection of the carburetor
for dirt wear and fuel deposits should always be done
before servicing the carburetor.
Carburetor Identification:
Tecumseh carburetors are identified by a manufacturing
number and date code stamped on the carburetor as
shown. When servicing carburetors, use the engine
model number or the manufacturing number on the
carburetor to find repair parts in the Master Parts Manual.
The engine has used both a split system and married
system carburetor. Below are the parts breakdowns for
the two carburetor's.
SPLIT
1
5
7
6
47
29
27
30
*
31
*
26
36
37
38
MANUFACTURING NUMBER
AND DATE CODE
TORX E-5
STUD
NOTE: LATER MODEL VECTOR CARBURETOR BODIES ARE
HELD ON WITH TORX E-5 STUDS. YOU WILL NEED THIS
SOCKET FOR REMOVAL. TECUMSEH PART NO. 670339.
Ref.
No. Part Name
1 Throttle Shaft & Lever Assy.
5 Dust Seal (Throttle)
6 Throttle Shutter
7 Throttle Shutter Screw
25 Float Bowl
25A Idle Restrictor
26 Float
27 Shaft, Float
29 Gasket, Float Bowl to Body
25A
25
32
39
30 Inlet Needle, Seat & Seat Retainer (Incl. 31)
*
31 Seat Retainer
*
32 Bowl Drain Assy.
36 Tube, Main Nozzle
37 O Ring, Main Nozzle Tube
38 Spring, Main Nozzle Tube
39 Float Bowl Retainer
47 Welch Plug, Idle Mixture Well
MARRIED
1
5
7
6
47
29
NOTE: The seat retainer may not be present on some engines. If you receive a retainer as a service part, install it.
*
27
36
37
38
26
25A
25
37A
39
40
30
*
31
*
38A
33
32
Ref.
No. Part Name
1 Throttle Shaft & Lever Assy.
5 Dust Seal
6 Throttle Shutter
7 Throttle Shutter Screw
25 Float Bowl
25A Idle Restrictor
26 Float
27 Float Shaft
29 Gasket, Float Bowl to Body
30 Inlet Needle, Seat & Seat Retainer (Incl. 31)
*
31 Seat Retainer
*
32 Bowl Drain Screw
33 Bowl Drain Washer
36 Tube, Main Nozzle
37 O Ring, Main Nozzle Tube
37A O Ring
38 Spring, Main Nozzle Tube
38A Spring
39 Float Bowl Retainer
40 Main Fuel Jet
47 Welch Plug, Idle Mixture Well
9
The carburetor is a float feed, nonadjustable type,
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with a 1 piece extruded aluminum body. The float
bowl, float, nozzle, and venturi are nonmetallic,
minimizing the corrosion and varnishing problems.
Common service areas of the carburetor are contained
in the fuel bowl. These areas are the float, needle,
seat and main nozzle. All of these parts can be serviced
without removing the carburetor body from the engine.
DRAIN INTO APPROVED CONTAINER
OUTDOORS, AWAY FROM OPEN FLAME.
FLOAT BOWL SERVICE. Disconnect and plug the fuel
line. Remove the bowl drain screw. Remove the float
bowl by snapping the bale spring towards the throttle
end of the carburetor.
IF A SCREW DRIVER OR SIMILAR TOOL IS USED
TO AID IN THE BAIL REMOVAL, CARE MUST BE
TAKEN NOT TO PERMANENTLY BEND THE
RETAINER.
AIR
BLEED
HOLES
SPLIT SYSTEM MAIN JET
JET AND NOZZLE ASSY.
"O" RING
MARRIED SYSTEM MAIN JET
The float is held in the float bowl by the float pin which
is pressed into tabs on top of the float support towers.
NOTE: To prevent damage to the float bowl, pull straight
up with a needle nose pliers in the pocket closest to the
main fuel well. Carefully lift the float out of the float bowl
and inspect for damage or deposits. Clean the idle
passageway with compressed air, or with tag wire.
IDLE PASSAGE
After the bowl gasket is removed, the parts contained
in the bowl can be inspected and serviced. Pull out the
main nozzle and spring. Inspect the main nozzle for
deposits, be sure to check the cross holes on the body
of the nozzle and the main orifice in the bottom of the
nozzle. Use compressed air or monofilament fishing
line to remove any deposits in the main jet or cross holes.
Remove the drain screw to access the spring, jet and
"O" ring. The main jet should be inspected and cleaned
if deposits exist.
MAIN NOZZLE
FLOAT
HINGE PIN
NOTE: The inlet needle is attached to the float and
should also be inspected for damage or deposits.
The inlet seat can be removed with a small wire hook or
a #2 crochet hook. Inspect the float bowl and main
nozzle area for sediment and deposits. Use a carburetor
cleaner to loosen and remove deposits and sediment.
INLET NEEDLE
SEATS AT
THIS POINT
INSERT GROOVED
FACE FIRST
10
INLET SEAT
RETAINING CLIP
IDLE PASSAGE
5/32" FLAT PUNCH
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SEAT
Place a new gasket on top of the float bowl with the
notch on the gasket aligned with the bump on the bowl
edge (the gasket will only fit onto the float bowl one
way.) Hold the float bowl to the carburetor body and
snap the retainer into position. Reinstall the bowl drain
screw, do not over tighten, reattach the fuel line.
PRESS IN UNTIL
SEAT RESTS ON
BODY SHOULDER
INLET NEEDLE
SEATS AT
THIS POINT
RETAINING CLIP
INSERT GROOVED
FACE FIRST
Install a new inlet seat into the float bowl. The grooved
side of the inlet seat goes into the float bowl first. Place
a drop of oil on the seat and press it in with a flat punch
until it seats. Do not scratch the inlet bore.
NOTE: Some models are equipped with a fuel inlet seat
retaining ring. If your replacement seat set comes with
a retaining clip install it on top of the seat.
Slide the inlet needle into the tabs on the float and put
the float pin into the hinge on the float. Carefully set the
float into position in the float bowl.
Be sure the needle drops into the fuel inlet. Snap the
float shaft into the tabs in the float bowl. It is not
necessary to adjust the float height even if the float has
been replaced.
Drop the main nozzle spring into the main nozzle well
in the float bowl. Put a small amount of oil on the main
nozzle “O” ring and push the nozzle into the main nozzle
well, “O” ring end first.
NOTE: Bowl service is all that is normally required for
routine carburetor maintenance.
Rebuilding the carburetor body:
Before disassembling the carburetor body, check the
throttle shaft and body for excessive wear. If there is
excessive wear to the throttle body, it should be
replaced.
To rebuild the carburetor body it is necessary to remove
the carburetor from the engine.
1. Remove the speed control plate.
2. Remove the air cleaner body from the carburetor.
3. Disconnect and plug the fuel line.
4. Remove the carburetor mounting studs.
5. Remove the governor link.
6. Drain the carburetor float bowl.
7. Disassemble the float bowl (see bowl service).
To properly clean the carburetor body, the welch plugs
should be removed to expose drilled passages. To
remove welch plug, sharpen a small chisel to a sharp
wedge point. Drive the chisel into the welch plug, push
down on chisel and pry plug out of position.
SMALL CHISEL
PIERCE PLUG WITH TIP
SPLIT SYSTEM
GASKET
ALIGNMENT
MARKER
MAIN NOZZLE
BLEED/JET
"O" RING IN GROOVE
SPRING
BOWL
DRAIN
In addition to this, the married system carburetor has
the "O" ring, main jet, and spring located behind the
drain system.
MARRIED SYSTEM
"O" RING
JET
SPRING
DRAIN SCREW
PRY OUT PLUG
DO NOT ALLOW
CHISEL POINT
TO STRIKE
CARBURETOR
BODY OR CHANNEL
REDUCER
SMALL CHISEL
WELCH PLUG TO
BE REMOVED
ABOUT 1/8" WIDE
After the welch plug is removed from the carburetor it
can be soaked in a commercial carburetor cleaner no
longer than 30 minutes. Be sure to follow the directions
on the container.
NOTE: Always pull the non metallic slip in venture out
before soaking in carburetor cleaner.
Reinstall the venture using the main nozzle to align it
correctly. The air bleed passages face the air filter.
After the carburetor has been soaked, all passages may
be probed with monofilament fishing line and
compressed air to open plugged or restricted passages.
GASKET
11
Install a new welch plug over the idle fuel chamber with
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the raised portion up. Use a punch equal to the size of
the plug, to flatten the plug. Do not dent or drive the
center of the plug below the top surface of the carburetor.
NOTE: To insure a good seal on this plug, we
recommend coating the seam with nail polish which is
gas resistant.
FLAT END PUNCH
Primer Bulb Service: To remove the primer bulb, grasp
the primer bulb with a needle nose pliers and roll the
pliers along the air cleaner body. After removing the
primer bulb, the retaining ring must be removed. Use a
screwdriver to carefully pry the retainer out of the air
cleaner body. Do not reuse old bulb or retainer.
NEW WELCH PLUG
SAME
DIAMETER OF PLUG
Install the throttle shaft and shutter (use a new shutter
screw and dust seal). The scribe mark on the shutter
must be in the 12 o’clock position.
NOTE: NEWER STYLE
CARBURETORS USE A
TORX T-10 SCREW
12 O'CLOCK POSITION
NOTE: THE BREATHER
SYSTEM HOSE MUST BE
RECONNECTED HERE.
NOTE: If the scribe mark is out of position the shutter
may stick.
To rebuild the Float Bowl, refer to the previous section
on float bowl service.
Install the carburetor to the engine using a new gasket.
The primer passage in the air cleaner body should be
cleaned before it is reinstalled over the carburetor.
After the primer bulb is removed, clean the primer
passages thoroughly.
Press the new bulb and retainer into position using a
deep reach socket as shown.
CAUTION: Wear safety glasses or goggles when
removing retainer.
Install air cleaner body over the carburetor using a new
gasket.
NOTE: The VLV models use a closed loop breather
system. The crankcase breather tube must be
reconnected to the air filter body
12
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