Vanguard OHV V-Twin User manual

TABLE OF CONTENTS
SAFETY, MAINTENANCE AND ADJUSTMENTS Section 1. . . . . . . . . . . . . . . . . .
TROUBLESHOOTING Section 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ENGINE DISASSEMBLY Section 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
FUEL SYSTEMS AND CARBURETION Section 4. . . . . . . . . . . . . . . . . . . . . . . . . .
GOVERNOR Section 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CYLINDER HEADS AND VALVES Section 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
STARTERS Section 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LUBRICATION SYSTEMS Section 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CYLINDERS AND CRANKCASE COVERS/SUMPS Section 9. . . . . . . . . . . . . . .
CRANKSHAFTS AND CAMSHAFTS Section 10. . . . . . . . . . . . . . . . . . . . . . . . . . . .
PISTONS, RINGS AND CONNECTING RODS Section 11. . . . . . . . . . . . . . . . . . .
ENGINE ASSEMBLY Section 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ENGINE SPECIFICATIONS Section 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
For Briggs & Stratton Discount Parts Call 606-678-9623 or 606-561-4983
www.mymowerparts.com

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Section 1
Safety, Maintenance and Adjustments
Page
AIR CLEANER SERVICE 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Round Air Cleaner 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Square Air Cleaner 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cyclonic Air Cleaner 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ARMATURE AIR GAP ADJUSTMENT 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BRIGGS & STRATTON NUMERICAL IDENTIFICATION SYSTEM 6. . . . . . . . . . . . . . . . . . . . . . . . .
CARBURETOR ADJUSTMENTS 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Models 290000 – 350000 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Performance ControlEEngines 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Models 351400, 380400, 351700, 380700 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CHOKE CONTROL ADJUSTMENT 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
COMBUSTION CHAMBER DEPOSITS 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
COOLING SYSTEM CLEANING 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CRANKCASE OIL 17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
FUEL AND OIL RECOMMENDATIONS 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel Recommendations 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Oil Recommendations 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
GOVERNOR ADJUSTMENTS 18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Static Governor Adjustment 18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dynamic Governor Adjustment 18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
IN THE INTEREST OF SAFETY 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MAINTENANCE AND ADJUSTMENTS SCHEDULE 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
OIL COOLER 22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
OVERHAUL PROCEDURE 24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Disassemble 24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inspection and Repairs 25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reassemble 25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SPARK PLUGS 22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SPEED CONTROL WIRE ADJUSTMENT 23. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TUNE UP PROCEDURE 24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
VALVE CLEARANCE ADJUSTMENT 23. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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IN THE INTEREST OF SAFETY
DANGER
•Before attempting to service this equipment,
read and understand this manual and the
operating instructions.
•Failure to follow instructions could result in
DEATH, SERIOUS INJURY (including paral-
ysis) or property damage.
FOLLOW INSTRUCTIONS
CAREFULLY !
* Briggs & Stratton does not necessarily know what
equipment this engine will power. For that reason,
carefully read and understand the operating instruc-
tions for the equipment your engine is powering.
THE OPERATING, MAINTENANCE &
REPAIR INSTRUCTIONS CONTAIN
SAFETY INFORMATION TO:
•Make you aware of hazards associated with
engines
•Inform you of the risk of injury associated with
those hazards, and
•Tell you how to avoid or reduce the risk of injury.
SAFETY ALERT SYMBOL
The safety alert symbol ( ) is used to identify
safety information about hazards that can result in
personal injury.
A signal word (DANGER, WARNING, or CAUTION)
is used with the alert symbol to indicate the
likelihood and the potential severity of injury. In
addition, a hazard symbol may be used to represent
the type of hazard.
DANGER indicates a hazard that, if not
avoided, will result in death or serious injury.
WARNING indicates a hazard that, if not
avoided, could result in death or serious injury.
CAUTION indicates a hazard that, if not
avoided, might result in minor or moderate injury.
CAUTION,when used without the alert symbol, in-
dicates a situation that could result in damage to
the engine.
NOTE: A NOTE is used to inform you of a method,
reference or procedure that could assist
with specific operations or procedures.
HAZARD SYMBOLS AND MEANINGS
Explosion
Toxic Fumes Moving Parts
Shock
Hot Surface
Kickback
Fire
Flying Objects
Eye Protection
Required
INTERNATIONAL SYMBOLS AND MEANINGS
Stop
Read Operator’s
Manual
Safety Alert Oil
Fuel Shutoff
Fuel
Choke Start Position

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Gasoline and its vapors are extremely
flammable and explosive.
Fire or explosion can cause severe
burns or death.
WHEN ADDING FUEL
•Turn engine OFF and let engine cool at least 2
minutes before removing gas cap.
•Fill fuel tank outdoors or in a well-ventilated
area. Keep gasoline and its vapors away from
sparks, open flames, pilot lights, heat, and
other ignition sources.
•Do not overfill fuel tank. Fill tank to
approximately 1-1/2 inches below top of neck
to allow for fuel expansion.
•Check fuel lines, tank, cap, and fittings
frequently for cracks or leaks. Replace if
necessary.
WHEN STARTING ENGINE
•Make sure spark plug, muffler, fuel cap and
air cleaner are in place.
•Do not crank engine with spark plug removed.
•If fuel spills, wait until it evaporates and the
vapors dissipate before starting engine.
•If engine floods, set choke to OPEN/RUN
position, place throttle in FAST position.
Crank until engine starts.
WHEN OPERATING EQUIPMENT
•Do not tip engine or equipment at an angle
that causes gasoline to spill.
•Do not choke carburetor to stop engine.
WHEN TRANSPORTING EQUIPMENT
•Transport with fuel tank EMPTY or with fuel
shut-off valve OFF.
WHEN STORING GASOLINE OR EQUIPMENT
WITH FUEL IN TANK
•Store away from furnaces, stoves, water
heaters or other appliances that have pilot
light or other ignition source. These can ignite
gasoline vapors.
WARNING
Kerosene and its vapors are
extremely flammable, and should
be handled with the same
precautions as gasoline.
WARNING
WARNING
Unintentional sparking can result
in fire or electric shock.
Unintentional start-up can result in
entanglement, traumatic amputa-
tion, or laceration.
BEFORE PERFORMING ADJUSTMENTS
OR REPAIRS
•Disconnect spark plug wire and keep it away
from spark plug.
•Disconnect battery at negative terminal (only
engines with electric start).
WHEN TESTING FOR SPARK
•Use approved spark plug tester.
•DO NOT check for spark with spark plug
removed.
WARNING
All fuel components should be
in good condition and properly
maintained.
•Repairs should only be made with
factory approved parts.
•Repair work should be done by a
qualified technician.
•Flexible supply lines should be
checked regularly to make sure
they are in good condition.
Replace damaged or leaking
components.

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WARNING
Engines give off carbon
monoxide, an odorless, colorless,
poison gas.
Breathing carbon monoxide can
cause nausea, fainting or death.
•Start and run engine outdoors.
•DO NOT start or run engine in enclosed area,
even if doors or windows are open.
•Inhalation of high concentrations of vapor,
even for short periods can cause uncon-
sciousness or might prove fatal.
•Inhalation may cause irritation to the nose and
throat, headache, nausea vomiting, dizziness,
and drowsiness.
•Unconsciousness or asphyxiation may result
in poorly ventilated areas or confined spaces.
WARNING
Running engines produce heat.
Engine parts, especially muffler,
become extremely hot.
Severe thermal burns can occur
on contact.
Combustible debris, such as
leaves, grass, brush, etc. can
catch fire.
•Allow muffler, engine cylinder and fins to cool
before touching.
•Remove accumulated combustibles from
muffler area and cylinder area.
•Install and maintain in working order a spark
arrester before using equipment on forest-
covered, grass-covered, brush-covered
unimproved land. The state of California
requires this (Section 4442 of the California
Public Resources Code). Other states may
have similar laws. Federal laws apply on
federal land.
WARNING
Rotating parts can contact or
entangle hands, feet, hair, clothing,
or accessories.
Traumatic amputation or severe
laceration can result.
•Operate equipment with guards in place.
•Keep hands and feet away from rotating
parts.
•Tie up long hair and remove jewelry.
•DO NOT wear loose-fitting clothing,
dangling drawstrings or items that could
become caught.
WARNING
Rapid retraction of starter cord
(kickback) will pull hand and arm
toward engine faster than you can
let go.
Broken bones, fractures, bruises
or sprains could result.
•When starting engine, pull cord slowly until
resistance is felt, then pull rapidly.
•Remove all external equipment/engine loads
before starting engine.
•Direct coupled equipment components such
as, but not limited to, blades, impellors,
pulleys, sprockets, etc., must be securely
attached.
WARNING
The engine exhaust from this product
contains chemicals known to the State
of California to cause cancer, birth
defects, or other reproductive harm.

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Additional Precautions
Before working on the engine, read and understand
the applicable sections of this manual. Follow all
safety warnings. Death, personal injury and/or prop-
erty damage may occur unless service instructions
are followed carefully.
DO NOT store, spill, or use gasoline near an open
flame, or near an appliance like a stove, furnace, or
water heater that uses a pilot light or creates a spark.
DO NOT refuel indoors or in an unventilated area.
DO NOT operate or tip engine/equipment at an
angle that causes gasoline spillage.
DO NOT operate engine if gasoline is spilled, when
smell of gasoline is present, or when other explosive
conditions exist. (Move equipment away from spill.
Avoid ignition until gasoline has evaporated.)
DO NOT transport engine with fuel in tank or fuel
shut-off valve open.
DO NOT choke carburetor to stop engine, especially
in an enclosed vehicle. (Gradually reduce engine
speed before stopping.)
DO NOT tamper with governor springs, links or other
parts to increase engine speed. (Run engine at speed
set for equipment manufacturer.)
DO NOT check for spark with spark plug removed.
(Use an approved tester.)
DO NOT run engine with blower housing or other
safety shields removed.
DO NOT crank engine with spark plug removed. (If
engine is flooded, place throttle in FAST position and
crank until engine starts.)
DO NOT strike flywheel with a hammer or hard object.
This could cause the flywheel to shatter in operation.
(Use only Briggs & Stratton approved tools and proce-
dures to remove the flywheel.)
DO NOT operate engine without a muffler. (Inspect
periodically and replace if worn or leaking. If engine
is equipped with muffler deflector, inspect periodically
and replace if necessary. Replacement parts must be
same as on original equipment.)
DO NOT operate engine with grass, leaves or other
combustible material accumulated in the muffler
area.
DO NOT touch hot muffler, cylinder, or fins which can
cause burns.
DO NOT start engine with air cleaner or air cleaner
cover removed.
DO NOT attempt to start engine with cutting blade
loose or removed. (Blade must be tight, otherwise
kickback may occur.)
DO NOT remove fuel tank cap or fill the fuel tank
while the engine is hot or running. DO NOT refuel in-
doors or in an unventilated area. Allow the engine to
cool at least 2 minutes before refueling.
WEAR suitable eye protection (safety glasses,
goggles or face shield) when performing repair pro-
cedures.
PREVENT ACCIDENTAL STARTING by discon-
necting spark plug wire from spark plug when servic-
ing engine or equipment. Disconnect negative wire
from battery terminal if equipped with electric start-
ing system.
USE ONLY genuine Briggs & Stratton parts or their
equivalent. The use of non-equivalent replacement
parts may damage the engine.
GASEOUS FUEL ENGINES – Check fuel lines and
fittings frequently for cracks or leaks. Replace as
necessary.

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BRIGGS & STRATTON NUMERICAL IDENTIFICATION SYSTEM
YOUR KEY TO THE WORLD'S FINEST ENGINES
This chart explains the unique Briggs & Stratton numerical model designation system. It is possible to determine most of the
important mechanical features of the engine by merely knowing the model number. Here is how it works
A. The first one or two digits indicate the approximate CUBIC INCH DISPLACEMENT.
B. The first digit after the displacement indicates the BASIC DESIGN SERIES, relating to cylinder
construction, ignition, general configuration, etc.
C. The second digit after the displacement indicates ORIENTATION OF CRANKSHAFT.
D. The third digit after the displacement indicates TYPE OF BEARINGS, and whether or not the
engine is equipped with REDUCTION GEAR or AUXILIARY DRIVE.
E. The last digit indicates the TYPE OF STARTER.
BRIGGS & STRATTON MODEL NUMBERING SYSTEM
FIRST DIGIT
AFTER DISPLACEMENT
SECOND DIGIT
AFTER DISPLACEMENT
THIRD DIGIT
AFTER DISPLACEMENT
FOURTH DIGIT
AFTER DISPLACEMENT
A B C D E
CUBIC INCH
DISPLACEMENT
BASIC
DESIGN SERIES
CRANKSHAFT
ORIENTATION
PTO BEARING,
REDUCTION GEAR,
AUXILIARY DRIVE,
LUBRICATIONă TYPE OF STARTER
ă6
ă8
ă9
10
11
12
13
16
18
19
20
21
22
23
24
25
28
29
30
31
32
35
38
40
42
43
44
46
47
52
54
58
0
1
2
3
4
5
6
7
8
9
A to Z
0 to 4 - Horizontal Shaft
5 to 9 - Vertical Shaft
A to G - Horizontal Shaft
H to Z - Vertical Shaft
0 - Plain Bearing/DU
NonĆFlange Mount
1 - Plain Bearing
Flange Mounting
2 - Sleeve Bearing
Flange Mounting
Splash Lube
3 - Ball Bearing
Flange Mounting
Splash Lube
4 - Ball Bearing
Flange Mounting
Pressure Lubrication
5 - Plain Bearing
Gear Reduction
(6 to 1) CCW Rotation
Flange Mounting
6 - Ball Bearing
Gear Reduction
(2 to 1) CCW Rotation
7 - Plain Bearing
Pressure Lubrication
8 - Plain Bearing
Auxiliary Drive (PTO)
Perpendicular to
Crankshaft
9 - Plain Bearing
Auxiliary Drive
Parallel to Crankshaft
A - Plain Bearing
Pressure Lubrication
Without Oil Filter
0 - Without Starter
1 - Rope Starter
2 - Rewind Starter
3 - Electric Starter Only
110 or 230 Volt Gear
Drive
4 - Electric Starter/110 or
230 Volt Gear Drive
with Alternator
5 - Electric Starter Only
12 or 24 Volt Gear
Drive
6 - Alternator Only
7 - Electric Starter
12 or 24 Volt Gear
Drive with Alternator
8 - Vertical Pull Starter or
Side Pull Starter
9 - Mechanical Starter
A - Electric Starter
12 or 24 Volt Gear
Drive with Alternator
and Inverter
EXAMPLE - To identify Model 303447
30 3 4 4 7
30 Cubic Inch Design Series 3 Horizontal Shaft Ball Bearing
Flange Mounting
Pressure Lubrication
Electric Starter
12 or 24 Volt Gear Drive
with Alternator
TYPE 1234Ć01, The type number identifies the engines mechanical parts, color of paint, decals, governed speed, and Original
Equipment Manufacturer.
CODE 01061201, The code is the manufacturing date and is read as follows
YEAR MONTH DAY ASSEMBLY LINE AND MANUFACTURING PLANT
01 06 12 01
Revised 4/04

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FUEL & OIL RECOMMENDATIONS
Fuel Recommendations
Gasoline Engines
•Use clean, fresh regular unleaded gasoline with a
minimum of 85 octane. Fresh fuel prevents gum
from forming in the fuel system or on essential
carburetor parts. Purchase fuel in a quantity that
can be used within 30 days.
•Do not use gasoline containing Methanol.
•Do not mix oil with gasoline.
•For engine protection use Briggs & Stratton Fuel
Stabilizer #5041 or single use pouch #5058
available from your Authorized Briggs & Stratton
Dealer.
CAUTION: Some fuel, called “oxygenated” or
“reformulated” gasoline, is gasoline blended
with alcohol or ether. Excessive amounts of
these blends can damage the fuel system or
cause performance problems. If any undesir-
able operating symptoms occur, use gasoline
with a lower percentage of alcohol or ether.
Inline Fuel Filter Service
Replace inline fuel filter yearly or every 100 hours,
whichever occurs first. Replace filter if dirt or water
are present. See illustrated parts list for correct
fuel filter.
Gaseous Fuel Engines
•Many state, county and city governments
require that service be performed ONLY
outdoors.
•Have a fan blowing across the engine BEFORE
loosening fuel line connections!
DANGER
AVOID INJURY! Gaseous fuel
systems should only be worked
on in a very well ventilated area.
NOTE: Gaseous fueled engines require special
equipment to remain emissions certified.
See a certified gaseous fuel dealer or a
certified OEM dealer for service.
Use clean fuel free of moisture or particulate
material, within the following values:
For propane (LPG) fueled engines, use commercial
grade HD% propane. Recommended fuel has a
minimum fuel energy of 2500 BTU/ft3,maximum
propylene content 5%, butane, heavier gas content
2.5%, minimum propane content 90%.
•Do not operate gaseous fueled equipment if the
fuel lock-off valve is missing or inoperative.
WARNING
AVOID INJURY! Gaseous fueled
equipment is equipped with an auto-
matic safety gas fuel lock-off valve.

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Oil Recommendations
Oil has four purposes. It cools, cleans, seals and lu-
bricates. During normal operation, small particles of
metal from the cylinder walls, pistons, bearings and
combustion deposits contaminate the oil. Dust par-
ticles from the air also contaminate the oil, forming
an abrasive mixture that can wear internal engine
parts if the oil is not changed regularly. Fresh oil as-
sists in cooling. Old oil gradually thickens and loses
its cooling ability and its lubricating qualities.
Briggs & Stratton OHV V-Twin engines are lubri-
cated with a gear-driven oil pump.
Use a high quality detergent oil classified “For Ser-
vice SJ or HIGHER” such as Briggs & Stratton 30
weight oil part #100005 or #100028. Detergent oils
keep the engine cleaner and retard the formation of
gum and varnish deposits. Do not use additives with
recommended oils.
°C-30
STARTING TEMPERATURE RANGE ANTICIPATED BEFORE NEXT OIL CHANGE
°F-20 0 20 40 60 80 100
-20 -10 0 10 20 30 40
**
32
Air cooled engines run hotter than automotive
engines. Use of multi-viscosity oils (10W-30,
etc.) in ambient temperatures above 40F
(4C) will result in high oil consumption. If
multi-viscosity oil is used, check oil level more
frequently to prevent any possible engine
damage due to lack of lubrication.
** SAE 30 oil, if used in ambient temperatures
below 40F (4 C) will result in hard starting
and possible engine damage due to inade-
quate lubrication.
Synthetic oil meeting ILSAC GF-2, API certifi-
cation mark and API service symbol with “SJ/
CF ENERGY CONSERVING” rating or higher,
is an acceptable oil at all temperatures.
NOTE: Use of synthetic oil does not alter
the required oil change intervals.
MAINTENANCE & ADJUSTMENTS SCHEDULE
The following maintenance schedule is a general guide. See the Engine Operating & Maintenance Instructions
for details on specific engine models.
Maintenance Schedule 8 Hours
or Daily
25 Hours
or Every
Season
50 Hours
or Every
Season
100 Hours
or Every
Season
500
Hours
Check oil level *
Change oil  Note #1
Change oil filter 
Clean/Replace air filter pre-cleaner  Note #2
Clean/Replace air filter cartridge  Note #2
Clean cooling system  Note #2
Inspect/clean spark arrester (if used) 
Replace or clean spark plugs 
Replace in-line fuel filter 
Remove combustion chamber deposits 
* Change oil after the first 5 to 8 hours of operation (break-in period), then after every 50 hours or every season.
NOTE: #1 – Change oil every 25 hours when operating under heavy load or in high temperatures.
NOTE: #2 – Clean more often under dusty conditions or when airborne debris is present. Replace air cleaner
parts when dirty.

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AIR CLEANER SERVICE
AVOID FIRES!
WARNING
•Never operate an engine with the air cleaner
assembly or air cleaner cartridge removed!
A properly serviced air cleaner protects internal en-
gine parts from airborne dirt and dust particles. If air
cleaner instructions are not followed, particles that
should be collected in the air cleaner will pass into
the engine. These particles are abrasive and will
cause the piston rings and cylinder bore to wear
quickly. As the rings and bore wear, the abrasive par-
ticles enter the crankcase and contaminate the oil,
forming an abrasive mixture that will wear internal
parts.
Examine the air cleaner on every engine brought in
for a check up or repair. If the air cleaner shows signs
of neglect, show it to the customer before cleaning.
Instruct the customer on proper care to assure long
engine life.
NOTE: Replace worn or damaged air cleaner gas-
kets and mounting gaskets to prevent dirt
and dust from entering engine through im-
proper sealing. Replace air cleaner mount-
ing bracket if bent.
Remove and service foam pre-cleaner, if equipped,
every 25 hours or every season, whichever occurs
first. Service cartridge every 100 hours or every sea-
son, whichever occurs first.
NOTE: Service air cleaner more often under dusty
conditions.
Round Air Cleaner
1. Remove cover (1), knob (2), plate (3), and air
cleaner cartridge (4) with pre-cleaner (5), Fig. 1
or Fig. 2.
Fig. 1
Ì
Ì
Ì
Ì





Fig. 2
ÑÑ
ÌÌ
ÌÌ





2. Remove foam pre-cleaner from cartridge.
3. Wash pre-cleaner in liquid detergent and water.
4. Squeeze dry in a clean cloth. Set aside.
5. Inspect cartridge. Replace if damaged or dirty.

1
10
CAUTION: DO NOT use petroleum solvents to
clean paper cartridge.
DO NOT oil paper cartridge.
DO NOT use pressurized air to clean or dry paper
cartridge.
6. Reinstall pre-cleaner over cartridge.
7. Install cartridge to air cleaner.
8. Install plate, knob and air cleaner cover.
Square Air Cleaner
1. Remove knob(s) (2) and cover assembly (1),
Fig. 3.
Fig. 3





2. Remove cartridge (4) and pre-cleaner (5) from
cover.
3. Wash pre-cleaner in liquid detergent and water.
4. Squeeze dry in a clean cloth. Set aside.
5. Inspect cartridge. Replace if damaged or dirty.
CAUTION: DO NOT use petroleum solvents to
clean paper cartridge.
DO NOT oil paper cartridge.
DO NOT use pressurized air to clean or dry paper
cartridge.
6. Install pre-cleaner in cover with foam toward
cover. (Nylon screen toward paper element.)
7. Install paper cartridge in cover with tabs on
cartridge (3) in slots of cover, Fig. 3.
8. Reinstall cover assembly on air cleaner body.
Cyclonic Air Cleaner
NOTE: The debris valve automatically discharges
dust and debris. There should be minimal
debris for removal.
1. Remove debris from the air cleaner by
squeezing the ends of the debris valve (5),
Fig. 4.
Fig. 4





2. Remove the cover (4) from the air cleaner
housing (1).
3. Remove the primary filter (3) and inspect.
Replace the filter if damaged, or dirty.
CAUTION: DO NOT clean or oil these filters.
DO NOT use pressurized air to clean or dry filters.
REPLACE filters if damaged or dirty
4. Inspect the safety filter (2).
NOTE: DO NOT remove the safety filter (2) as part
of the inspection.
If it is necessary to remove the safety filter,
Fig. 5, be sure all debris is removed from the
air cleaner housing before removal.
Replace the safety filter with every third
replacement of the primary filter, or if
damaged or dirty.
5. Reinstall filter(s).
6. Reinstall air cleaner cover.

1LOCKED FOR PRINTING – SELECT SECT. NEEDED >
11
Fig. 5


ARMATURE AIR GAP ADJUSTMENT
1. Loosen screws holding armature in place. Slide
armature away from flywheel and tighten one of
the screws.
2. Rotate flywheel until magnet is under armature
laminations.
3. Place thickness gauge (1) between magnet and
armature laminations, Fig. 6.
•All EXCEPT Models 540000, 610000 – Use
0.008” – 0.012” (0.20 – 0.30 mm) gauge.
•Models 540000, 610000 – Use 0.005 – 0.007”
(0.13 – 0.18 mm) gauge.
Fig. 6

4. Loosen screw on the armature. Allow armature
to be pulled against the gauge by the flywheel
magnet. Tighten both armature screws to 25 in.
lbs. (3 Nm).
5. Rotate flywheel to remove gauge.
6. Repeat procedure for the other armature.
CARBURETOR ADJUSTMENTS
Models 290000 – 350000
The VanguardOHV twin cylinder engine carbure-
tor fuel mixture adjustment procedure is unique. Per-
form adjustments exactly in the sequence shown.
NOTE: If engine is equipped with Performance
Controlelectronic governor see separate
adjustment procedure.
Initial Adjustment
1. Turn idle mixture screw (1), Fig. 7, CLOCKWISE
until it just seats. DO NOT FORCE.
2. Turn valve COUNTERCLOCKWISE 1-1/4
turns.
This setting will permit engine to start. Final adjust-
ment will be made with engine running.
NOTE: Parts removed for clarity.
ÌÌ
ÌÌ
Fig. 7
ÌÌ
ÌÌ

If engine is equipped with a secondary governor
spring, Fig. 8, check governor lever adjustment
procedure before starting engine.
(1) Primary Governor Spring
(2) Loop (faces UP)
(3) Secondary Governor Spring
(4) Loop Over Tab
(5) #2 Hole (Generators)
(6) #1 Hole (Remote Control)

1
12
Fig. 8






Final Adjustment
All carburetor adjustments performed with the en-
gine running must be made with the air cleaner
installed.
•Tools Required, Fig. 9:
Tachometer #19200 or #19389
Tang Bender #19352
1. Start engine. Run for approximately 5 minutes to
allow engine to warm up.
2. Move control lever on equipment to SLOW
position.
Fig. 9
1938919200
19352
3. Hold throttle lever (2) against idle speed screw
(1), Fig. 10. Temporarily adjust idle to RPM
shown below.
a. 1400 RPM – Governed Idle Spring #805453
(RED).
b. 1100 RPM – Governed Idle Spring #805454
(WHITE).
Fig. 10
ÌÌ
ÌÌ
ÌÌ


4. Turn idle mixture screw slowly CLOCKWISE (1)
until engine speed just starts to slow (LEAN
mixture), Fig. 11.
Fig. 11
Ì
Ì
Ì
Ì
ÌÌ
ÌÌ
ÌÌ
ÌÌ


5. Then turn idle mixture screw COUNTER-
CLOCKWISE (3) until engine speed just starts to
slow (RICH mixture).
6. Turn screw to mid point (2) between RICH and
LEAN.
7. Hold throttle lever against idle speed adjustment
screw and re-adjust idle to RPM shown below:
a. 1200 RPM – Governed Idle Spring #805453
(RED).
b. 900 RPM – Governed Idle Spring #805454
(WHITE).
8. Release throttle lever. Note RPM.
9. If necessary bend governed idle tang (5) with
Tang Bender #19352 (4), Fig. 12, to obtain RPM
shown:
a. 1750 RPM – Governed Idle Spring #805453
(RED).
b. 1100 RPM – Governed Idle Spring #805454
(WHITE).

1LOCKED FOR PRINTING – SELECT SECT. NEEDED >
13
Fig. 12

10. If the carburetor is equipped with an idle mixture
limiter cap install it at this time.
a. Position limiter cap (7) so that stop(s) on
limiter cap are at mid point between stop(s)
on carburetor body, Fig. 13.
Fig. 13


b. Press limiter into position using Knock Out
Pin, #19135 (6) as shown.
11. With equipment control lever in SLOW position
and engine running at governed idle, use Tang
Bender, #19352 (9), to bend throttle restrictor
tang (8) so that tang just contacts governor lever
(10), Fig. 14.
12. Move equipment control to FAST position.
Engine should accelerate smoothly.
Re-adjust idle mixture valve 1/8 turn richer if
necessary.
Fig. 14



Performance ControlEngines
NOTE: All carburetor adjustments with engine
running must be made with the air cleaner
correctly installed.
1. Start engine and run it for approximately 5
minutes to allow engine to reach operating
temperature.
2. Activate idle down device, or ground BLUE wire
(1) from control module using a jumper wire (2),
Fig. 15.
3. Temporarily adjust idle speed to 1400 RPM.
Fig. 15


4. Turn idle mixture screw slowly CLOCKWISE (3)
until engine speed just starts to slow (LEAN
mixture), Fig. 16.
5. Then turn idle mixture valve COUNTERCLOCK-
WISE (5) until engine speed just starts to slow
(RICH mixture).
6. Turn valve to mid point (4) between RICH and
LEAN.
7. Re-adjust idle speed to 1750 RPM.

1
14
NOTE: Idle speed may vary according to OEM
specifications.
Fig. 16
ÌÌ
ÌÌ
ÌÌ
ÌÌ
Ì
Ì
Ì
Ì


8. Deactivate idle-down device, or remove jumper
wire. Engine should accelerate smoothly to top
governed speed. Re-adjust idle mixture screw
1/8 turn richer if necessary.
9. If the carburetor is equipped with an idle mixture
limiter cap, install it at this time.
a. Position limiter cap (7) so that stop on limiter
cap is at mid point between stops on
carburetor body, Fig. 17.
Fig. 17


b. Press limiter into position using Knock Out
Pin #19135 (6).
Models 351400, 380400, 351700 and 380700
The OHV twin cylinder engine carburetor fuel
mixture adjustment procedure is unique. Perform
adjustments exactly in the sequence shown.
Horizontal crankshaft engines (1) and vertical
crankshaft engines (2) are shown in Fig. 18.
Initial Adjustment
1. Turn idle mixture screw for #1 cylinder CLOCK-
WISE until it just seats. DO NOT FORCE,
Fig. 18.
Fig. 18


2. Then turn screw COUNTERCLOCKWISE 3/4
turn.
3. Repeat for #2 cylinder.
This setting will permit engine to start. Final adjust-
ment will be made with engine running.
Final Adjustment
Carburetor adjustments performed with engine run-
ning must be made with the air cleaner correctly
installed.
NOTE: Idle mixture adjustment MUST be per-
formed with the engine running at 1200
RPM.
Tools Required:
•Tachometer #19200 or #19389
•Tang Bender #19352
1. Start engine and run it for approximately 5
minutes to allow engine to reach operating
temperature.
2. Move equipment control lever to SLOW
position.
3. Hold throttle lever (1) against idle speed screw
(2), Fig. 19. Temporarily adjust idle to 1200
RPM.

1LOCKED FOR PRINTING – SELECT SECT. NEEDED >
15
4. While holding throttle lever, SLOWLY turn idle
mixture screw for #1 cylinder CLOCKWISE until
engine speed just starts to slow (LEAN mixture).
Fig. 19


5. Then turn idle mixture screw (3) COUNTER-
CLOCKWISE 3/8 turn, Fig. 20.
NOTE: It may be necessary to re-adjust idle speed
to 1200 RPM before proceeding.
6. Adjust idle mixture screw for #2 cylinder as
described in steps 4 and 5.
7. If necessary, re-adjust idle speed screw to RPM
shown below.
a. 1200 RPM – Governed Idle Spring #805453
(RED).
b. 900 RPM – Governed Idle Spring #805454
(WHITE).
8. Release throttle lever. Note RPM.
Fig. 20

9. If necessary, use Tang Bender #19352 (6),
Fig. 21. Bend governed idle tang LEFT to
INCREASE (4), right to DECREASE (5) engine
speed to obtain RPM shown:
a. 1750 RPM – Governed Idle Spring #805453
(RED).
b. 1100 RPM – Governed Idle Spring #805454
(WHITE).
NOTE: Parts removed for clarity.
Fig. 21


10. If carburetor is equipped with idle mixture limiter
caps, install at this time.
a. Position limiter cap (8) so that stop on limiter
cap is at mid point between stops on carbu-
retor body. Press limiter into position using
Knock Out Pin #19135 (7) as shown in,
Fig. 22.
b. Repeat for other idle mixture valve.
Fig. 22

11. With equipment control lever in SLOW position
and engine running at governed idle, use Tang
Bender #19352 (10), to bend throttle restrictor
tang (9) so that it just contacts governor lever
(11), Fig. 23.
12. Move equipment control to FAST position.
Engine should accelerate smoothly. Re-adjust
idle mixture valve 1/8 turn richer if necessary.

1
16
Fig. 23
11


Choke Control Adjustment
NOTE: Be sure choke control wire is installed in #2
hole (2) in choke lever, Fig. 24.
Fig. 24




1. Place choke control lever on equipment in
CHOKE position.
2. Loosen control casing clamp screw (4).
3. Move control casing and wire (3) until choke is
completely closed (1).
4. Tighten casing clamp screw.
Combustion Chamber Deposits
Combustion chamber deposits should be removed
every 500 hours or whenever cylinder heads are
removed.
WARNING
•Wear eye protection whenever using
compressed air to clean parts.
AVOID EYE INJURY!
Remove deposits from combustion chamber and
around valves using a wire brush or scraper. With
piston at Top Dead Center (TDC), remove
combustion chamber deposits from top of piston.
Use care to prevent combustion chamber deposits
from entering push rod or oil return cavity in cylinder.
Take care not to damage cylinder, top of piston,
cylinder head and cylinder head gasket surfaces.
NOTE: Remove only the combustion chamber de-
posits. It is not necessary to remove the dis-
coloration marks on the piston, valves and
cylinder head. These marks are normal and
will not affect engine operation.
Remove the loose deposits from around the top ring
land area using compressed air or a soft bristle
brush.
Cooling System Cleaning
Grass particles, chaff or dirt can clog the air cooling
system, especially after prolonged service in cutting
dry grass or very dirty air. Operating with a clogged
cooling system can cause overheating and engine
damage. Cleaning the cooling system should be a
regular maintenance operation, performed yearly or
every 100 hours, whichever comes first.
All Except Models 540000, 610000
Fig. 25 shows the blower housing removed and
areas to be cleaned (1) on the Vanguardengine.
Fig. 25


1LOCKED FOR PRINTING – SELECT SECT. NEEDED >
17
Models 540000, 610000
1. Use acoin or screwdriver to twist the Easy Clean
Accesspanel fasteners (1), Fig. 26
COUNTERCLOCKWISE until a CLICK is heard
(approx. 3/4 turn).
2. Remove the panel (2).
Fig. 26



3. Blow compressed air from the PTO side to clean
the cooling fins (3), Fig. 27 around each cylinder
and to back flush the cooling system.
Fig. 27

4. Insert the access panel tab into the blower hous-
ing slot. Be certain the access panel is correctly
engaged to the blower housing. Push the panel
completely into the housing. Twist each fastener
CLOCKWISE until it “CLICKS”, approx. 3/4 turn.
CAUTION: DO NOT run the engine unless the
Easy Clean Accesspanel is correctly installed.
Crankcase Oil
Change Oil and Filter
Drain oil while the engine is still warm. See Fig. 28
for approximate drain plug locations on vertical
crankshaft engines; Fig. 29 for horizontal crankshaft
engines.
Fig. 28
Ì
Ì
ÌÌ
ÌÌ
Ì
Ì
Ì
Ì
Ì



Fig. 29


1. Remove oil drain plug (1). Drain oil into
approved container.
2. Remove dipstick.
3. Replace oil filter (2) every 100 hours. Before
installing new filter, lightly oil filter gasket with
new engine oil.
4. Screw filter on CLOCKWISE (arrow) by hand
until gasket contacts filter adapter. Hand tighten
an additional 1/2 - 3/4 turn.
5. Replace drain plug.
6. Refill crankcase slowly with new oil of proper
service classification and viscosity grade. Refill
to FULL mark on dipstick.
CAUTION: DO NOT OVERFILL THE ENGINE
WITH OIL!

1
18
The crankcase capacity of VanguardV-Twin
engines is approximately:
•All (except Model 540000) – 48 oz. (1.4
liters) with filter
•Models 540000, 610000 – 79 oz. (2.3
liters) with filter
•Models 540000, 610000 – 71 oz. (2.1
liters) without filter
NOTE: When checking oil level, screw the dipstick
all the way in for accurate readings.
7. Start engine. Run at IDLE for 30 seconds and
stop engine. Recheck oil level and add if
required. Restart engine and check for oil leaks.
Governor Adjustments
CAUTION
•Incorrect adjustment could result in engine
overspeeding, causing engine damage,
property damage or personal injury.
AVOID INJURY! Complete the
governor static adjustment BEFORE
starting or running engine.
Static Governor Adjustment
(Before Running Engine)
1. Loosen governor lever nut. Push on governor
lever (1) until throttle is wide open, Fig. 30.
Fig. 30


Do not bend governor link or distort
governor lever.
CAUTION:
2. Use a screwdriver (2) to rotate governor shaft
COUNTERCLOCKWISE as far it will go. Torque
governor nut to 70 in. lbs. (8 Nm).
3. Install throttle and choke control cables and
check for proper operation.
Dynamic Governor Adjustment
NOTE: Carburetor mixture adjustments must be
made before adjusting governed idle,
throttle restrictor and top no-load RPM.
•Tools Required, Fig. 31:
Tachometer #19200 (1) or #19389 (3)
Tang bender #19352 (2)
Fig. 31



Manual Friction and Remote Speed Controls
Governor spring is installed in #1 hole (3) in governor
lever, Fig. 32.
Start and run engine for approximately 5 minutes to
allow engine to warm up.
1. Move control lever to SLOW position.
2. Use tool #19352 (1) to bend governed idle tang
(2) to obtain RPM shown:
a. 1750 RPM – Governed Idle Spring #805453
(RED).
b. 1100 RPM – Governed Idle Spring #805454
(WHITE).

1LOCKED FOR PRINTING – SELECT SECT. NEEDED >
19
Fig. 32


3. With equipment control lever in SLOW position
and engine running at governed idle RPM, use
Tang Bender #19352 (1), to bend throttle
restrictor tang (4) so that it just contacts
governor lever (5), Fig. 33.
Fig. 33



4. Refer to Service Engine Sales Microfiche,
MS-6225 or the Service Engine Sales Manual,
MS-4052, for Top No-Load RPM by engine
Model and Type Number.
5. Move control throttle lever to FAST position and
check engine RPM.
6. Use Tool #19352 (1) to bend tang (6) UP (7) to
increase and DOWN (8) to decrease engine
speed, to obtain desired Top No-Load RPM,
Fig. 34.
NOTE: Air cleaner removed for clarity.
Fig. 34




Fixed Speed Adjustable – Except Generators
Governor spring is installed in #1 hole in governor
lever (3), Fig. 35.
Start and run engine for approximately 5 minutes to
allow engine to warm up.
1. Turn fixed speed adjustable control nut counter-
clockwise until control swivel contacts slow
speed stop.
2. Use Tool #19352 (1) to bend governed idle tang
(2) to obtain RPM shown:
a. 1750 RPM – Governed Idle Spring #805453
(RED).
b. 1100 RPM – Governed Idle Spring #805454
(WHITE).
Fig. 35


3. Use Tool #19352 (1) to bend throttle restrictor
tang (4) so that it just contacts governor lever (5),
Fig. 36.
Fig. 36



NOTE: Be sure the governor spring is installed in #1
hole in governor lever (9), Fig. 37.
4. Refer to Service Engine Sales Microfiche,
MS-6225 or the Service Engine Sales Manual,
MS-4052, for Top No-Load RPM by engine
Model and Type Number.