Briggs & Stratton 750 DOV Series Specifications

Briggs & Stratton
Repair Manuals for other
Briggs & Stratton Engines:
273521 Twin Cylinder OHV Air-Cooled Engines
276781 Single Cylinder OHV Air-Cooled Engines
271172 Twin Cylinder L-Head Air-Cooled Engines
270962 Single Cylinder L-Head Air-Cooled Engines
276535 Two-Cycle Snow Engines
CE8069 Out of Production Engines (1919-1981)
700/750 Series DOV Air-Cooled Engines
Quality Starts With A
Master Service Technician
www.ThePowerPortal.com (Dealers)
BRIGGSandSTRATTON.COM (Consumers)
Post office box 702
Milwaukee, WI 53201 USA
©2009 Briggs & Stratton Corporation
12/09
Part No. 277527-12/09
BRIGGS&STRATTON
CORPORATION
700/750 Series DOV
Air-Cooled Engines
FORWARD
This manual was written to assist engine technicians and service personnel with the repair and
maintenance procedures for Briggs & Stratton engines. It assumes that persons using this manual have
been properly trained in and are familiar with the servicing procedures for these products, including the
proper use of required tools and safety equipment and the application of appropriate safety practices.
Persons untrained or unfamiliar with these procedures or products should not attempt to perform such
work.
Proper maintenance and repair is important to safe, reliable operation of all engines and engine-driven
systems. The troubleshooting, testing, maintenance, and repair procedures described in this manual are
appropriate for the Briggs & Stratton engines described herein. Alternative methods or procedures may
pose risk to personal safety and the safety and/or reliability of the engine and are not endorsed or
recommended by Briggs & Stratton.
All information, illustrations, and specifications contained in this manual were based on the data available
at the time of publication. Briggs & Stratton Corporation reserves the right to change, alter, or otherwise
improve the product or the product manuals at any time without prior notice.
Briggs & Stratton offers two complementary publications to enhance understanding of engine technology,
maintenance, and repair. (Neither publication, however, is a substitution for a recognized training program
for engine technicians.)
• For consumers, Small Engine Care & Repair (p/n 274041) provides a comprehensive overview of how
small air-cooled engines work, basic troubleshooting, and step-by-step maintenance procedures.
• For engine technicians and consumers alike, an in-depth study of engine theory and operation can be
found in the textbook Small Engines (p/n CE8020).
Both publications can be purchased at BRIGGSandSTRATTON.COM or through a local Authorized Briggs
& Stratton Service Dealer.
Copyright © 2009 Briggs & Stratton Corporation
All rights reserved.
No part of this manual may be reproduced or transmitted in any form or by any means, electronic or
mechanical, including photocopying or recording by any information storage and retrieval system, without
prior written permission from Briggs & Stratton Corporation.
6
This engine repair manual includes the following
engine models:
• MODEL 090600
• MODEL 100600
• MODEL 100800
SECTION 1 - Safety, Maintenance and Adjustments
SECTION 2 - Troubleshooting
SECTION 3 - Exhaust Systems
SECTION 4 - Fuel Systems and Carburetion
SECTION 5 - Governor Systems
SECTION 6 - Cylinder Heads and Valves
1
2
3
4
5
6
SECTION 7 - Starters
7
SECTION 8 - Lubrication Systems
SECTION 9 - Cylinders, Covers and Sumps
8
9
SECTION 10 - Crankshafts, Camshafts, Balancing Systems, and Gear Reductions
10
SECTION 11 - Pistons, Rings and Connecting Rods
11
SECTION 12 - Engine Specifications
12
THISPROPER SERVICE AND REPAIR IS IMPORTANT
TO THE SAFE, ECONOMICAL AND RELIABLE
SECTION 1 - SAFETY, MAINTENANCE, AND ADJUSTMENTS
SAFETY INFORMATION - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 4
ENGINE MAINTENANCE - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 7
FUEL AND OIL RECOMMENDATIONS - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 7
1
MAINTENANCE CHART - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 7
OIL CHANGE- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 8
AIR FILTER - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 8
SPARK PLUG - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 8
COOLING SYSTEM - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 9
CHARGING BATTERY - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 9
COMBUSTION CHAMBER - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -10
ENGINE ADJUSTMENTS - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -10
THROTTLE CABLE ADJUSTMENT - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -10
GOVERNOR ADJUSTMENTS- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -10
ADJUST VALVE CLEARANCE - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -12
ADJUST READYSTART CHOKE LINK- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -12
ADJUST ARMATURE AIR GAP- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -13
ADJUST ALTERNATOR AIR GAP - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -14
FLYWHEEL BRAKE - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -15
3
1
SAFETY INFORMATION
This repair manual contains safety information
that is designed to:
• Make you aware of hazards associated
with engines.
• Inform you of the risk of injury associated
with those hazards.
1
• Tell you how to avoid or reduce the risk of
injury.
1
Signal Words in Safety Messages
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 which, if not
avoided, will result in death or serious
injury.
WARNING
Before attempting to service this equipment,
read and understand this manual and the
operating instructions of the engine and the
equipment it powers.
Failure to follow instructions could result in
property damage, serious injury (including
paralysis) or even death.
Hazard Symbols and Meanings
FIRE
EXPLOSION
ELECTRIC
SHOCK
EXPLOSIVE
PRESSURE
HOT
SURFACE
GOGGLES
ENTANGLEMENT
KICKBACK
AMPUTATION
TOXIC
FUMES
READ
MANUAL
CHEMICAL
BURNS
WARNING indicates a hazard which, if
not avoided, could result in death or
serious injury.
CAUTION indicates a hazard which, if
not avoided, could result in minor or
moderate injury.
NOTICE indicates a situation that could
result in damage to the product.
Prior to work, read and understand the section(s)
of this manual that pertain to the job. Follow all
safety warnings.
• Always use fresh gasoline. Stale fuel can
cause gum deposits in the carburetor
and cause leakage, flow restrictions, or
other problems.
• Check fuel lines and fittings frequently for
cracks or leaks and replace if necessary.
4
WARNING
Fuel and its vapors are extremely flammable and explosive.
Fire or explosion can cause severe
burns or death.
WARNING
Battery posts, terminals, and related accessories contain lead and lead compounds - chemicals known to the State of California to cause
cancer and reproductive harm. Wash hands
after handling.
WARNING
Certain components in this product and its
related accessories contain chemicals known
to the State of California to cause cancer, birth
defects, or other reproductive harm. Wash
hands after handling.
WARNING
Briggs & Stratton does not approve or authorize the use of these engines on 3-wheel All
Terrain Vehicles (ATVs), motor bikes, fun/recreational go-karts, aircraft products, or vehicles intended for use in competitive events.
Use of these engines in such applications
could result in property damage, serious injury
(including paralysis), or even death.
When adding fuel:
•
Turn engine OFF and let engine cool for at least 2 minutes
before removing the fuel cap.
•
Fill fuel tank outdoors or in a well-ventilated area.
•
Do not overfill fuel tank. To allow for expansion of the gasoline, do not fill above the bottom of the fuel tank neck.
•
Keep gasoline away from sparks, open flames, pilot lights,
heat and other ignition sources.
•
Check fuel lines, tank, cap, and fittings frequently for cracks
or leaks. Replace if necessary.
•
If fuel spills, wait until it evaporates before starting engine.
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 before starting engine.
•
If engine floods, set choke (if equipped) to OPEN/RUN position. Place throttle (if equipped) in FAST and crank until
engine starts.
When operating equipment:
•
Do not tip engine or equipment at an angle which would
cause fuel to spill.
•
Do not choke carburetor to stop engine.
•
Never start or run the engine with the air cleaner assembly
(if equipped) or the air filter (if equipped) removed.
When changing oil:
•
If you drain the oil from the top oil fill tube, the fuel tank must
be empty or fuel can leak out and result in a fire or explosion.
When transporting equipment:
•
Transport with fuel tank empty or with fuel shut-off valve set
to OFF.
When storing gasoline or equipment with fuel in the tank:
•
Store away from furnaces, stoves, water heaters, or other
appliances that have a pilot light or other ignition source
because they can ignite gasoline vapors.
WARNING
1
1
WARNING
The engine exhaust from this product contains
chemicals known the State of California to
cause cancer, birth defects, and other reproductive harm.
•
•
•
Running engines produce heat. Engine
parts, especially mufflers, 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 fins, and radiator
to cool before touching.
Remove accumulated debris from muffler area
and cylinder fins.
It is a violation of California Public Resource
Code, Section 4442, to use or operate the
engine on any forest-covered, brush-covered,
or grass-covered land unless the exhaust system is equipped with a spark arrester, as
defined in Section 4442, maintained in effective
working order. Other States and Federal jurisdictions may have similar laws. Contact the
original equipment manufacturer, retailer, or
dealer to obtain a spark arrester designed for
the exhaust system installed on this engine.
5
WARNING
WARNING
Unintentional sparking can result in fire
or electrical shock.
Unintentional start-up can result in
entanglement, traumatic amputation, or
severe lacerations.
1
Charging batteries produce hydrogen
gas. Do not store or charge a battery
near an open flame or device that utilizes a pilot light or can create a spark.
WARNING
Before performing adjustments or repairs:
•
•
1
Disconnect spark plug wire and keep it away
from spark plug.
Disconnect the negative (-) battery terminal.
Kerosene and its vapors are extremely
flammable and should be handled with the
same precautions as gasoline.
When testing for spark:
•
•
Use approved spark plug tester.
Do not check for spark with spark plug
removed.
WARNING
Damaged, worn, or loose fuel components can leak fuel. Explosion or fire
could result.
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 an enclosed area,
even if doors and windows are open.
•
•
•
•
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.
WARNING
WARNING
•
•
Starting engine creates sparking.
Sparking can ignite nearby flammable
gases.
Explosion and fire could result.
If there is a natural or LP gas leak in the area,
do not start engine.
Do not use pressurized starting fluids because
vapors are flammable.
•
•
WARNING
•
•
•
•
•
Rotating parts can contact or entangle
hands, feet, hair, clothing, or accessories.
Traumatic amputation or severe lacerations 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 entangled in the equipment.
WARNING
Prolonged or repeated contact with used
motor oil could cause injury.
•
•
6
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 the starter cord
slowly until resistance is felt and then pull rapidly to avoid kickback.
Remove all external equipment/engine loads
before starting engine.
Direct-coupled equipment components, such
as but not limited to blades, impellers, pulleys,
and sprockets, must be securely attached.
Used motor oil has been shown to cause skin
cancer in certain laboratory animals.
Thoroughly wash exposed areas with soap and
water.
ENGINE MAINTENANCE
Fuel and Oil Recommendations
viscosity for the outdoor temperature range
expected.
Fuel must meet these requirements:
• Clean, fresh, unleaded gasoline.
• A minimum of 87 octane / 87 AKI
(90 RON).
1
• Gasoline with up to 10% ethanol
(gasahol) or up to 15% MTBE (methyl
tertiary butyl ether) is acceptable.
NOTICE: Do not use unapproved gasoline, such
as E85. Do not mix oil in gasoline or modify the
engine to run on alternate fuels. This will damage
the engine components and void the engine
warranty.
To protect the fuel system from gum formation,
mix a fuel stabilizer into the fuel. All fuel is not the
same. If starting or performance problems occur,
change fuel providers or change brands. This
engine is certified to operate on gasoline. The
emissions control system for this engine is EM
(Engine Modifications).
High Altitude
At altitudes over 5,000 feet (1524 meters), a
minimum 85 octane / 85 AKI (89 RON) gasoline
is acceptable. To remain emissions compliant,
high altitude adjustment is required. Operation
without this adjustment will cause decreased
performance, increased fuel consumption, and
increased emissions.
Operation of the engine at altitudes below 2,500
feet (762 meters) with the high altitude kit is not
recommended.
Fresh Start® Fuel Cap
Some engines are equipped with a Fresh Start®
fuel cap. The Fresh Start fuel cap is designed to
hold a cartridge (sold separately) that contains
fuel stabilizer.
Oil must meet these requirements:
• Briggs & Stratton Warranty Certified oils
are recommended for best performance.
• Other high-quality detergent oils are
acceptable if classified for service SF,
SG, SH, SJ or higher.
• Do not use special additives.
Outdoor temperatures determine the proper oil
viscosity for the engine.
Use the chart (Figure 1-1) to select the best
1
Figure 1 - 1
MAINTENANCE CHART
First 5 Hours
• Change oil
Every 8 Hours or Daily
• Check engine oil level
• Clean area around muffler and
controls
• Clean finger guard
Every 25 Hours or Annually
• Clean air filter*
• Clean pre-cleaner*
Every 50 Hours or Annually
• Change engine oil
• Check muffler and spark arrester
Annually
• Replace air filter
• Replace pre-cleaner
• Replace spark plug
• Replace fuel filter
• Clean air cooling system*
* In dusty conditions or when airborne debris is
present, clean more often.
7
Oil Change
Change oil after the first 5 hours of operation.
After that, change oil after every 50 hours of
operation. Change oil more often if engine is
operated in dirty or dusty conditions, under
heavy loads, or in high ambient temperatures.
2. Gently tap air filter cartridge on a hard
surface to loosen debris. Replace
cartridge if very dirty.
3. Wash foam pre-cleaner in warm, soapy
water, then rinse and allow to air dry.
4. Reassemble the air cleaner system.
1. Remove oil drain plug from side or bottom
of engine and drain oil while the engine is
still warm.
1
2. Install drain plug.
3. Fill crankcase with correct amount of new
oil.
1
4. Start engine and run at idle for a minute or
so.
5. Shut engine off and wait for oil to settle
back into the cylinder.
6. Check dipstick. If necessary, add more oil
slowly to bring level to FULL mark on
dipstick.
Figure 1 - 2
Air Filter
A correctly serviced air filter protects internal
engine parts from airborne dirt and dust. Poor
filter maintenance will allow dirt and dust to be
drawn into the engine, causing wear to the intake
system and contamination of the oil. Dirt in the oil
forms an abrasive mixture which wears down
moving parts.
WARNING
Fuel and its vapors are extremely flammable and explosive.
Fire or explosion can cause severe
burns or death.
•
Never start or run the engine with the air
cleaner assembly or the air filter removed.
NOTE: Do not use pressurized air or solvents to
clean the filter. Pressurized air can damage the
filter and solvents will dissolve the filter.
1. Remove air cleaner cover (A and B,
Figure 1-2). Remove pre-cleaner (C) from
cartridge (D).
8
Spark Plug
The spark plug should be replaced every year.
NOTICE
Spark plugs have different thread lengths
and heat ranges. When changing a spark
plug, use only the specified replacement,
otherwise engine damage could occur.
NOTE: In some areas, local law requires using
resistor spark plugs to suppress radio frequency
interference.
1. Disconnect spark plug wire.
2. Remove and inspect spark plug for wear
and damage. Replace spark plug if
electrodes are burned away, or the
porcelain is cracked.
3. Do not sand-blast or bead-blast the spark
plug. Clean by scraping or wire brushing,
and then washing in a commercial solvent.
4. Using a wire gage, check and set the gap
(A, Figure 1-3) per Section 12 Specifications.
1
1
Figure 1 - 4
Charging Battery
1. Clean the battery of all dirt and corrosion.
2. Clean, then lightly grease the terminals.
Figure 1 - 3
5. Re-install spark plug and torque to values
listed in Section 12 - Engine
Specifications.
6. Connect spark plug wire.
3. Bring the battery to full charge using a
taper charge (automatically reduces
charge rate).
NOTE: Do not exceed a charge rate of 1/10
ampere for every ampere of battery rating.
Consult the battery manufacturer for maximum
charge recommendations.
Cooling System
WARNING
Running engines produce heat.
Severe burns can occur on contact.
•
•
Allow muffler, engine cylinder fins, and radiator
to cool before touching.
Remove accumulated combustibles from muffler area and cylinder area.
Dirt or debris can restrict air flow and cause the
engine to overheat, resulting in poor
performance and reduced engine life. Continued
operation with a clogged cooling system can
cause severe overheating and possible engine
damage. Clean these areas (A, Figure 1-4)
yearly or more often when dust or airborne
debris is present.
NOTE: If the battery gets hot to the touch or is
spitting acid (gassing) excessively, unplug the
charger periodically.
4. With the battery fully charged, check the
specific gravity readings of each cell with a
temperature-compensated Battery
Hydrometer (Figure 1-5). All readings
should be above 1.250 (compensating for
temperature). If the readings vary by
0.050 or if all cells read less than 1.225,
replace the battery.
NOTICE: Do not use water to clean the engine.
Water could contaminate the fuel system. Use a
brush or dry cloth to clean the engine.
Figure 1 - 5
9
Combustion Chamber
1
1
Remove combustion chamber deposits every
500 hours or whenever the cylinder head is
removed.
With the piston at Top Dead Center (TDC),
scrape deposits from top of piston and upper
bore with a plastic scraper.
Remove the loosened deposits from around the
top ring land area using compressed air or a
shop vacuum and a soft bristle brush.
cylinder. Do not damage bore, top of piston,
cylinder head, or gasket mounting surfaces.
It is not necessary to remove the discoloration
marks on the piston, valves, and/or cylinder
head. These marks are normal and will not affect
engine operation.
NOTICE: Use care to prevent debris from
entering the valve lever or oil return cavities in
ENGINE ADJUSTMENTS
Throttle Cable Adjustment
The remote control wire should measure 2.125”
(54mm) when extended outside the casing
(A, Figure 1-6). After installation, the travel (B) of
the remote control wire must be at least 1.375”
(35 mm). If the travel of the remote control wire
does not reach the minimum distance, use the
following procedure to adjust the cable:
1. Loosen casing clamp screw (C).
2. Move throttle lever to FAST position.
3. Move casing in direction of arrow (D) until
slack is removed.
4. Tighten casing clamp screw. Torque to
values listed in Section 12 - Engine
Specifications.
Figure 1 - 6
Governor Adjustments
A complete governor system adjustment
includes a static adjustment, engine warm-up,
and top no-load adjustment. Be sure to complete
all steps.
Static Adjustment
1. Loosen nut (A, Figure 1-7) until governor
lever (B) moves freely from governor
crank (C).
2. Move throttle linkage (D) until throttle plate
(E) is wide open.
10
NOTE: Choke valve (F) closes when opening the
throttle plate.
3. While holding linkage, tighten governor
lever nut. Torque to values listed in
Section 12 - Engine Specifications.
4. Before starting engine, manually actuate
throttle linkage to check for binding.
1
1
Figure 1 - 8
Figure 1 - 7
Top No-Load Adjustment
1. Start engine and run at idle speed until it
reaches operating temperature.
2. Place throttle lever (G, Figure 1-8) in FAST
position.
3. Using Tachometer #19200 or #19389 (H),
and Tang Bender #19229 or #19352 (J),
bend spring tang (K) to obtain correct top
no-load RPM.
NOTE: Correct top no-load RPM for each modeltype-trim can be found in the engine replacement
data on Briggs & Stratton websites.
11
Adjust Valve Clearance
Adjust ReadyStart Choke Link
Perform this adjustment while the engine is cold.
NOTE: Check valve clearance while the engine
is cold.
1. Insert a narrow gauge such as a
screwdriver, rod, or pencil (A, Figure 1-9)
into the spark plug hole (B) until it touches
the piston (C). Cut away view is shown.
1
2. Observe the movement of the gauge and
turn the flywheel (D) clockwise past top
dead center on the compression stroke
until the piston has moved down the bore
0.25 in. (6.4 mm).
1
1. Using pliers, bend adjusting loop (A,
Figure 1-10) on choke link (B) until choke
lever gap (C) measures 0.000 - 0.060 in.
(0.000 - 1.52 mm). When properly
adjusted, the choke plate (D) will be fully
closed. Reshape wire to keep it parallel
(E) after adjusting loop.
3. Valve clearance is checked by placing a
feeler gauge (E) between the lever arm
adjusting screw (F) and the valve cap (G).
4. Loosen the adjusting screw nut (H) with a
wrench.
5. Using an allen wrench, turn the adjusting
screw (F) to obtain the correct clearance.
6. Tighten the adjusting screw nut (H) to the
torque values listed in Section 12 - Engine
Specifications.
7. Recheck clearance after tightening nut.
Figure 1 - 10
Figure 1 - 9
12
Adjust Armature Air Gap
1. Disconnect spark plug boot (A, Figure 111) and secure away from spark plug.
2. Loosen screw (B) and stud (C).
3. Slide armature (D) away from flywheel.
4. Tighten stud to secure armature.
5. Line up flywheel magnets (E) with
armature.
1
6. Insert a strip of gauge material (F)
(0.006 - 0.014 in. or 0.15 - 0.36 mm)
between flywheel magnet and both legs of
armature.
1
7. Loosen stud and allow magnet to pull
armature against gauge (G).
8. Tighten fasteners and torque to values
listed in Section 12 - Engine
Specifications.
9. Rotate flywheel to remove gauge.
Figure 1 - 11
13
Adjust Alternator Air Gap
1. Remove spark plug.
2. Loosen alternator screws (A, Figure 1-12).
and slide alternator (B) away from
flywheel.
3. Tighten one screw to secure alternator.
4. Line up flywheel magnet (D) with
alternator.
1
5. Insert a strip of gauge material (C)
(0.006-0.014 in. or 0.15-0.36 mm)
between flywheel magnet and both legs of
alternator.
1
6. Loosen screw and allow magnet to pull
alternator against gauge.
7. Tighten fasteners and torque to values
listed in Section 12 - Engine
Specifications.
8. Rotate flywheel to remove gauge.
Figure 1 - 12
14
Flywheel Brake
The flywheel brake is part of the safety control
system required for some applications. While
running at the FAST speed position, the flywheel
brake MUST stop the engine within three
seconds when the operator releases the
equipment safety control.
Test Brake Torque
1. Disconnect spark plug wire.
2. Remove static guard/rewind assembly.
3. Unscrew and remove fuel tank.
4. Remove dipstick and oil fill tube.
6. Using a torque wrench (A, Figure 1-13)
and socket to fit the flywheel nut, turn
flywheel clockwise with brake engaged.
While turning at a steady rate, torque
value should be 26 lb.-in. (3 Nm) or higher.
7. If reading is low, check thickness of brake
pad (B). Replace brake assembly if
thickness is less than 0.090” (2.28mm).
8. If brake pad thickness is acceptable,
adjust control cable to position pad closer
to flywheel when safety control is in RUN
position.Repeat Step 6.
9. Replace brake assembly if correct
adjustment cannot be made.
5. Unscrew and remove blower housing.
Figure 1 - 13
15
1
1
Remove Flywheel Brake
1. Disconnect and remove spring from brake
anchor.
2. Disconnect safety control cable from brake
assembly.
3. Loosen brake screw (A, Figure 1-14) but
do not remove.
1
4. Rotate bracket to relieve tension on screw
(B) and remove, then remove screw (A).
5. Press stop switch tang to disconnect stop
wire, then remove brake assembly.
1
6. Disconnect wires on interlock switch, if
equipped.
Figure 1 - 14
Install Flywheel Brake
1. Install stop switch wire and bend end of
wire 90°. Install wires on interlock switch, if
equipped.
2. Install brake assembly on cylinder and
torque mounting screws to values listed in
Section 12 - Engine Specifications.
3. Connect safety control cable and install
brake spring.
4. Actuate brake system to ensure proper
movement, then test brake torque as
previously described.
5. Install blower housing, oil fill tube, dipstick,
fuel tank, and static guard/rewind
assembly. Torque all screws to values
listed in Section 12 - Engine
Specifications.
16
SECTION 2 - TROUBLESHOOTING
SYSTEMS CHECK - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 18
CHECK IGNITION - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 18
CHECK CARBURETION - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 19
CHECK COMPRESSION - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 19
ELECTRICAL SYSTEMS - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 20
EQUIPMENT USED FOR TESTING - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 20
ALTERNATOR TESTING - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 21
STARTER MOTOR TESTING- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 22
BATTERY TESTING - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 23
17
2
1
SYSTEMS CHECK
Most complaints concerning engine operation
can be classified as one or a combination of the
following:
• Will not start
• Hard starting
1. Ignition
• Lack of power
2. Carburetion
• Runs rough
• Vibration
2
• Overheating
1
Once equipment sources are ruled out, the
cause for most of these symptoms can be
determined by performing a systems check in the
following order:
3. Compression
This check-up can usually be done in a matter of
minutes and is the quickest and surest method of
determining the cause of such problems.
• High oil consumption
What appears to be a problem with the engine
may actually be the fault of the equipment.
Following is a list of some common engine
symptoms and their relationship to equipment
problems.
No Start - Hard Start
• Loose belt or blade
• Cranking under load
1) Check Ignition
Engine Stopped
With spark plug installed, attach Ignition Tester
#19368 to spark plug lead and ground the other
end of the tester (Figure 2-1). Pull the starter
rope or activate the electric starter (if equipped).
If spark jumps the tester gap, you may assume
the ignition system is functioning satisfactorily.
• Misadjusted controls
• Interlock system malfunction
Engine Will Not Stop
• Equipment stop switch not functioning
• Engine ground wire damaged or
disconnected
Vibration
• Bent cutter blades
• Loose spindles and couplings
• Bent/broken deck or weldments
• Bent crankshaft
• Loose equipment mounting bolts
Figure 2 - 1
• Damaged or worn belts and pulleys
Engine Running
If engine runs but misses during operation, a
quick check to determine whether the ignition is
at fault can be made by installing Ignition Tester
#19368 between the spark plug lead and spark
plug (Figure 2-2). If spark is good but engine
misses, install a new spark plug.
• Out of balance impeller
Power Loss
• Bind or drag in moving parts of
equipment
• Grass build-up under deck
• No lubrication in equipment gear box
• Excessive belt tension
18
A simple check to determine if the fuel is getting
to the combustion chamber through the
carburetor is to remove the spark plug and pour
a small quantity of gasoline through the spark
plug hole. Replace the plug. If the engine fires a
few times and then stops, look for the same
conditions as for a dry plug.
3) Check Compression
Figure 2 - 2
If spark does not occur, look for:
Use Leakdown Tester #19545 to check the
sealing capabilities of the compression
components.
Follow the instructions provided with the tester to
perform the leakdown test.
• Improperly operating interlock system
• Shorted equipment or engine stop switch
wire
• Incorrect armature air gap
• Armature failure
2) Check Carburetion
Before making a carburetion check, be sure the
fuel tank has an ample supply of fresh, clean
gasoline.
Be sure the shutoff valve, if equipped, is open
and fuel flows freely through the fuel line. If fuel
fails to flow or is slow, check for plugged fuel cap
vent, fuel line restriction or plugged fuel filter.
Be sure throttle and choke controls are properly
adjusted.
If engine cranks but will not start, remove and
inspect the spark plug.
NOTE: Any air leaks at the connections or
fittings of the tester will affect the accuracy of the
test.
Listen for air leaking from the cylinder head
gasket, carburetor, exhaust system, and the
crankcase breather tube.
• Air flowing between the cylinder and
cylinder head indicates that the cylinder
head gasket is leaking.
• Air flowing from the carburetor indicates
air is leaking past the intake valve and
seat.
• Air flowing from the exhaust system
indicates air is leaking past the exhaust
valve and seat.
• Air flowing from the crankcase breather
tube or high oil fill dipstick tube indicates
air is leaking past the piston rings.
If plug is wet, look for:
• Over choking
• Excessively rich fuel mixture
Possible Causes for Poor Compression:
• Water in fuel
• Loose cylinder head bolts
• Float needle valve stuck open
• Blown head gasket
• Plugged air cleaner
• Burned valves, valve seats and/or loose
valve seats
• Fouled spark plug
If plug is dry, look for:
• Leaking carburetor or intake manifold
gaskets
• Gummy or dirty carburetor, fuel filter, fuel
lines or fuel tank
• Insufficient tappet clearance
• Warped cylinder head
• Warped valve stems
• Worn bore and/or rings
• Broken connecting rod
• Float needle valve stuck closed
• Inoperative fuel pump (if equipped)
• Inoperative fuel shut off solenoid (if
equipped)
19
2
1
ELECTRICAL SYSTEMS
Equipment Used for Testing
2
1
Digital Multimeter
A digital multimeter is recommended for all
electrical testing of Briggs & Stratton engines.
The meter can be used to read volts, ohms,
amperes, and to test diodes.
The Fluke® Digital Multimeter #19464 and the
UNI-T® Digital Multimeter #19581 are available
from your Briggs & Stratton source of supply.
NOTICE: The digital multimeters are equipped
with fuses to prevent damage to the meter if the
input limits are exceeded. Check the fuses if the
meter displays a reading of 0.00 when testing
DC Volts output.
Refer to the Fluke® Operator’s Manual for this
procedure. Replacement fuses #19449 for Series
II meters or #19571 for Series III meters are
available from your Briggs & Stratton source of
supply.
The UNI-T® Operator’s Manual lists the fuse
replacement procedure and type of replacement
fuses required.
Figure 2 - 4
Starter Motor Test Fixture
A starter motor test fixture may be made from
1/4” (6mm) steel stock (Figure 2-5).
1. Drill two 3/8” (10mm) holes for starter
mounting bracket (B).
2. Using same spacing, drill an additional
3/8” (10mm) hole (A) for alternate starter
mounting position.
3. Using a #7 bit, drill two holes for mounting
Tachometer #19200. Tap the holes for 1/
4-20 NC screws (C).
DC Shunt
The Fluke® meter will withstand DC input of 1020 amps for up to 30 seconds.
The UNI-T® meter will withstand DC input of 10
amps for up to 10 seconds.
When checking DC output on 10 and 16 amp
regulated systems, the DC Shunt #19468
(Figure 2-3) is required to avoid blowing a fuse in
either of the meters.
Figure 2 - 5
Figure 2 - 3
Tachometer
Tachometers #19200 (A) or #19389 (B, Figure 24) are available from your Briggs & Stratton
source of supply.
20
Other Equipment
A growler or armature tester (checks armature
for continuity, shorts, and opens) is available
from an Automobile Diagnostic Service supplier.
Also, a known good 12 Volt battery is required
when testing starting systems or alternators.
Alternator Testing
The following alternator test procedures were
developed using the Fluke® Digital Multimeter.
When performing alternator tests with the
UNI-T® Digital Multimeter, refer to the operating
manual supplied with that meter for the proper
procedure.
All test values will be the same regardless the
meter used.
5. Attach RED test clip to output lead (A,
Figure 2-7).
6. Attach BLACK test clip to charging lead
(B).
NOTE: Before testing alternator output, use an
accurate tachometer to temporarily adjust the
engine speed to the RPM specified in the test
instructions.
2
1
When testing alternators, perform the tests in the
following sequence:
1. Test alternator output.
2. Test diode(s) or regulator-rectifier (if
equipped).
The 0.5 Amp, DC alternator (Figure 2-6) is
designed to operate as an integral part of the
engine and is separate from the starting and
ignition system. It is intended to provide DC
charging current for a 12 Volt battery.
• Unregulated
• 0.5 Amps DC for charging battery
• One black lead (A) from stator
• White connector (B) output lead
Figure 2 - 7
7. Install tachometer, then start and run
engine at 2800 RPM. Meter should display
no less than 0.5 Amp DC.
8. If low or no output, check alternator air
gap. Adjust to value listed in Section 12 Engine Specifications.
9. If alternator air gap is within specification
and there is still low or no output, replace
alternator.
Figure 2 - 6
1. Disconnect charging lead to battery at
white connector.
2. Insert RED test lead into 10 Amp
receptacle in meter.
3. Insert BLACK test lead into COM
receptacle in meter.
4. Rotate selector to DC Amps position.
21
Starter Motor Testing
Before assuming an electric starter requires
service, check the engine for freedom of rotation
by removing the spark plug and turning the
crankshaft over by hand. Any belt, clutch, or
other parasitic load will affect the starter cranking
performance, so ensure their effects are
minimized.
The following list is given to aid in diagnosing
problems for the 12 Volt starting system.
1. Engine Cranks Slowly
2
• Parasitic load affecting performance
1
• Discharged, defective, or incorrect
battery
• Faulty electrical connection (battery
circuit)
• Dirty or worn starter motor commutator,
bearing, weak magnets, etc.
• Wrong engine oil viscosity for ambient
temperatures
• Defective starter clutch
• Flywheel brake misadjusted
• Battery leads too long or wire diameter
too small
2. Engine Will Not Crank
• Improperly operating interlock system
• Discharged battery
• Loose or corroded electrical connections
Check Starter Motor Drive and Clutch
When the starter switch is activated, the pinion
gear should rise, engage the flywheel ring gear,
and crank the engine. The pinion gear must
rotate counterclockwise, as viewed from the
gear. If the starter motor drive does not react
properly, check the helix and pinion gear for free
operation. If the pinion gear sticks, clean the
helix and gear with a mild solvent and
compressed air. If the pinion continues to stick,
replace the entire starter drive assembly.
NOTE: Do not oil the pinion gear or clutch helix.
The starter motor clutch is designed to prevent
damage from shock loads such as engine
backfire. If the clutch slips while cranking,
replace the entire starter drive assembly.
Test Starter Motor
1. Clamp starter motor test fixture in vise
(Figure2-8).
2. Remove starter motor from engine and
mount to fixture.
NOTICE: Do not clamp the motor housing in a
vise or strike with a hammer. Starter motors
contain ceramic magnets that can be damaged if
the motor housing is hit, deformed, or dented.
• Open circuit in starter motor switch
• Open circuit in starter motor
• Brushes sticking
• Inoperative starter solenoid
• Blown fuse in equipment wiring harness
3. Set meter to DC Amps position.
4. Connect the optional starter switch
(A, Figure 2-8), starter motor, battery (F),
black lead (C), red lead (D), shunt (E), and
tachometer (B).
3. Starter Motor Spins But Does Not Crank
Engine
• Sticking pinion gear
• Damaged pinion or ring gear
• Starter motor clutch slipping
• Incorrect rotation due to reversed motor
polarity
Figure 2 - 8
22
5. Activate starter motor and note readings of
meter and tachometer.Take reading after
meter stabilizes (approximately 2-3
seconds).
With a fully-charged battery, the starter motor
should deliver 6500 RPM (minimum) and 35
Amps (maximum). If the starter motor does not
meet these specifications, it must be replaced.
Battery Testing
A 12 Volt, lead acid, wet cell battery is required
to operate the starter motor. This type is
available as a wet charge or dry charge battery.
The wet charged maintenance-free battery is
filled with electrolyte and sealed at the time
production. The level of electrolyte cannot be
checked.
The dry charge battery requires electrolyte to be
added at the time the battery is placed in service.
Before activating a dry charge battery, read and
follow the manufacturer’s recommended
procedure.
WARNING
Storage batteries give off explosive hydrogen gas during recharging.
Slightest spark will ignite hydrogen and
cause explosion.
Battery electrolyte fluid contains acid and
is extremely caustic.
Contact with battery contents will cause
severe chemical burns.
A battery presents a risk of electrical shock
and high short circuit current.
•
•
•
•
•
•
DO NOT dispose of a battery in a fire.
DO NOT allow any open flame, spark, heat, or
lit cigarette during and for several minutes after
charging a battery.
DO NOT open or mutilate the battery.
Wear protective goggles, rubber apron, and
rubber gloves.
Remove watches, rings, or other metal objects.
Use tools with insulated handles.
Check Battery and Cable Sizes
The following battery size recommendations are
based on the minimum temperature expected
and the correct weight of oil being used.
• 30 Amp. Hr. +20ºF (-6ºC) or higher
• 40 Amp. Hr. -5ºF (-20ºC) or higher
• 50 Amp. Hr. -15ºF (-26ºC) or higher
The following cable sizes are based on the total
distance from the battery positive (+) post to the
starter switch and/or solenoid, plus the ground
return to the battery negative (-) post.
• #6 AWG - 4 ft. (1.2m) or less
• #5 AWG - 5 ft. (1.5m) or less
• #4 AWG - 6 ft. (1.8m) or less
23
2
1
WARNING
Battery posts, terminals, and related
accessories contain lead and lead
compounds - chemicals known to the State
of California to cause cancer and
reproductive harm. Wash hands after
handling.
2
1
Check Battery Installation
1. Ensure the battery is in a holder with a flat
base. Tighten holder down evenly until
snug. DO NOT over tighten.
2. Clean, then lightly grease the terminals.
3. Connect positive (+) cable to positive
battery post FIRST, to prevent sparks from
accidental grounding. Tighten connector
securely.
4. Connect negative (-) cable to negative
battery post. Tighten connector securely.
Testing Battery
1. With the battery fully charged, check the
specific gravity readings of each cell with a
temperature-compensated Battery
Hydrometer (Figure 2-9). All readings
should be above 1.250 (compensating for
temperature). If the readings vary by
0.050 or if all cells read less than 1.225,
replace the battery.
Figure 2 - 9
2. Set the digital multimeter to DC volts
position.
3. Install the battery in the equipment.
24
4. Disconnect wire from spark plug and
ground ignition using Ignition Tester
#19368.
5. Attach RED meter test clip to positive (+)
battery terminal. Attach BLACK meter test
lead to negative (-) battery terminal.
6. Turn switch to START. Meter should
display 9 volts or more while cranking
engine. If less than 9 volts, replace
battery.
NOTICE: To prevent damage to the starter
motor, do not crank starter for more than 15
seconds without allowing starter to cool at least 2
minutes.
SECTION 3 - EXHAUST SYSTEM
EXHAUST SYSTEM - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -26
REMOVE GUARD AND MUFFLER - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -27
INSPECT EXHAUST SYSTEM - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -27
INSTALL GUARD AND MUFFLER- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -27
1
3
25
EXHAUST SYSTEM
1
3
Figure 3 - 1
26
Some engines may be equipped with an exhaust
system (muffler, bracket, and hardware) supplied
by the equipment manufacturer. Contact the
equipment manufacturer for muffler service
information.
The exhaust system covered in this section is
supplied by Briggs & Stratton.
Remove Guard and Muffler
1. Remove screws (A, Figure 3-1) holding
muffler guard (B). Remove guard and set
aside.
2. Bend back tabs on screw lock (C) and
remove screws (D), muffler (E), and
gasket (F). Discard gasket.
Install Muffler and Guard
1. Insert screws with new screw lock into
muffler and place new exhaust gasket on
end of screws.
2. Lightly coat screw threads with Valve
Guide Lubricant #93963.
3. Position new gasket and thermostat on
cylinder head, then install muffler
assembly.
4. Tighten screws to values listed in Section
12 - Engine Specifications, then bend the
screw lock tabs up against the head of the
mounting screws.
5. Install muffler guard with screws. Torque
to values listed in Section 12 - Engine
Specifications.
3. Remove thermostat (G) and gasket (H).
Discard gasket.
Inspect Exhaust System
All exhaust system components must be
inspected whenever the exhaust system is
disassembled. Check the muffler mounting
bracket and/or muffler adapters for cracked
welds or breakage. Check the muffler for split
seams, loose internal parts, or cracked welds.
Replace any damaged parts with new original
equipment parts. Never reinstall broken or
damaged components.
27
1
3
1
3
28
SECTION 4 - FUEL SYSTEM AND CARBURETION
FUEL TANK - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -30
CARBURETOR - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -32
4
4
29
FUEL TANK
4
4
Figure 4 - 1
30
Removal
WARNING
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 for at
least 2 minutes before removing the fuel cap.
•
Fill fuel tank outdoors or in a well-ventilated
area.
•
Do not overfill fuel tank. To allow for expansion
of the gasoline, do not fill above the bottom of
the fuel tank neck.
•
Keep gasoline away from sparks, open flames,
pilot lights, heat and other ignition sources.
•
Check fuel lines, tank, cap, and fittings frequently for cracks or leaks. Replace if necessary.
•
If fuel spills, wait until it evaporates before
starting engine.
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 before
starting engine.
•
If engine floods, set choke (if equipped) to
OPEN/RUN position. Place throttle (if
equipped) in FAST and crank until engine
starts.
When operating equipment:
•
Do not tip engine or equipment at an angle
which would cause fuel to spill.
•
Do not choke carburetor to stop engine.
•
Never start or run the engine with the air
cleaner assembly (if equipped) or the air filter
(if equipped) removed.
When changing oil:
•
If you drain the oil from the top oil fill tube, the
fuel tank must be empty or fuel can leak out
and result in a fire or explosion.
When transporting equipment:
•
Transport with fuel tank empty or with fuel shutoff valve set to OFF.
When storing gasoline or equipment with fuel in
the tank:
•
Store away from furnaces, stoves, water heaters, or other appliances that have a pilot light
or other ignition source because they can
ignite gasoline vapors.
1. Drain the fuel into an appropriate
container.
2. Remove air cleaner cover (A, Figure 4-1)
and gas cap.
3. Remove screws and the static guard/
rewind assembly (B).
4. Remove the trim cover and blower
housing assembly (C).
5. Release clamp and pull hose off the tank
fitting (D). Remove screws, washers, and
spacers at top and bottom of tank then lift
tank off engine.
4
Inspection
1. Clean gummy or dirty fuel tanks with
Briggs & Stratton Carburetor Cleaner
#100041 or #100042, or equivalent.
4
2. Inspect fuel tank for:
• Corrosion
• Leaks
• Broken mounting brackets
3. Check fuel cap and filler neck for:
• Proper seals
• Vents
Clean or replace parts as required.
Installation
1. Install fuel hose to tank fitting and secure
with hose clamp. Position tank on engine
and install screws, washers, and spacers
at top and bottom of tank. Torque screws
to values in Section 12 - Engine
Specifications.
2. Install trim cover and blower housing
assembly.
3. Install static guard/rewind assembly.
Torque screws to values listed in Section
12 - Engine Specifications.
4. Install gas cap and air cleaner cover.
5. Partially fill tank with fuel and check for
leaks. Repair as necessary.
31
CARBURETOR
4
4
Figure 4 - 2
32
The DOV, 700/750-Series engine is equipped
with a ReadyStart® Carburetor, which utilizes a
thermostatically controlled choke system,
requiring no primer or manual choke. The
linkages and carburetor body have no
serviceable components.
Remove Carburetor
WARNING
Before servicing the carburetor or other fuel
system components, drain all fuel from the
tank and turn OFF the fuel valve (if equipped).
Do not attempt to stop the fuel flow by plugging
the fuel hose.
1. Remove casing clamp (A, Figure 4-2) and
disconnect throttle cable (if equipped)
from throttle lever.
2. Remove air cleaner cover, filters (B), base
screws, base (C), and gasket (D). Discard
the gasket.
3. Release clamp and disconnect fuel hose
from carburetor.
4. Remove two carburetor mounting screws
(E).
5. Carefully remove carburetor from control
bracket (F). Rotate the carburetor to
disconnect the choke link (G), and
governor link (J).
6. Remove gasket (K), spacer (L), and o-ring
(M) between control bracket and
carburetor. Discard gasket and o-ring.
Disassemble Carburetor
1. Remove the fixed main jet (bowl nut, N)
and fiber washer (P), then remove the fuel
bowl (R) and the bowl gasket (S) from the
carburetor body. Discard the fiber washer
and the gasket.
2. Remove the float hinge pin (T), float (U),
and inlet needle (V). Discard the hinge pin,
and inlet needle.
3. If damaged, remove the choke return
spring (H) and discard. Note orientation of
spring before removal.
NOTE: Do not disassemble the carburetor body
or choke and throttle levers.
Inspect and Clean Carburetor
1. Inspect openings in the carburetor body
for evidence of wear or damage. If found,
replace the entire carburetor assembly.
2. Inspect the choke shaft, choke valve,
throttle shaft, and throttle valve for
evidence of wear or damage. If found,
replace the entire carburetor assembly.
3. Using Carb/Choke Cleaner #100041 or
#100042, clean inside and outside
surfaces of carburetor, then follow with
compressed air to dry.
NOTE: Do not soak the carburetor in carb/choke
cleaner or it will be damaged.
4
4. If any passages remain plugged after
cleaning, replace the entire carburetor
assembly.
4
Assemble Carburetor
Consult the Illustrated Parts List to obtain the
appropriate carburetor overhaul kit before
reassembling the carburetor.
NOTE: Install new gaskets and o-rings whenever
carburetor is removed for service.
1. Install new choke return spring, if removed
previously.
2. Install new hinge pin, float, and new inlet
needle.
3. Install new bowl gasket with the fuel bowl.
Install new fiber washer and the fixed main
jet. Torque to values listed in Section 12 Engine Specifications.
4. Attach governor link and choke link to
carburetor.
5. Place spacer with new gasket and o-ring
on control bracket.
6. Position carburetor on spacer and install
screws. Torque to value listed in Section
12 - Engine Specifications.
NOTE: Use new screws or apply Loctite® to
original screws to prevent loosening from
vibration.
7. Connect fuel hose to carburetor and
secure with clamp.
8. Using new gasket, install air cleaner
components to carburetor. Torque screws
to values listed in Section 12 - Engine
Specifications.
9. Connect throttle cable (if equipped) to
throttle lever and secure with casing
clamp. Torque screw to value listed in
Section 12 - Engine Specifications.
33
4
4
34
SECTION 5 - GOVERNOR SYSTEM
GOVERNOR SYSTEM - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -36
LINKAGE AND SPRING ORIENTATION - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -37
TOP NO-LOAD RPM - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -37
GOVERNOR SERVICE- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -37
4
5
35
GOVERNOR SYSTEM
4
5
Figure 5 - 1
36
Linkage and Spring Orientation
Governor Service
Be sure to note orientation of linkages and
springs before removing (Figure 5-2).
The mechanical governor is part of the oil slinger
assembly (A, Figure 5-1) attached to the sump.
The governor crank (B) is mounted in the
cylinder assembly.
Disassemble
1. Drain oil from engine into an appropriate
container.
2. Remove burrs and clean the crankshaft
PTO, the carefully remove sump from
engine and discard the gasket.
4
3. Loosen the governor lever nut and slide
the lever off the governor crank and
disconnect from the governor link. Set
aside.
Figure 5 - 2
Top No-Load RPM
Briggs & Stratton supplies engines with an
adjustable top no-load RPM, which the
equipment manufacturers set to their own
specifications. Do not exceed these limitations.
NOTE: Correct top-no-load RPM for each modeltype-trim can be found in the engine replacement
data on Briggs & Stratton websites.
Top no-load RPM should be checked with a
tachometer when the engine is operating on a
completely assembled unit. The equipment
should be operated under no-load when making
this check.
If a governor spring must be replaced, consult
the appropriate Illustrated Parts List for the
correct part number. After the spring is installed,
check the top no-load RPM with an accurate
tachometer, as noted above, and adjust as
required. (See Section 1 - Safety, Maintenance,
and Adjustments).
4. Remove push nut or clip and washer (C)
from governor crank. Remove burrs and
clean the governor crank, then remove
crank from inside of cylinder.
NOTE: Inspect governor gear for worn weight
pins and chipped or missing gear teeth before
removing. Any time the governor gear is
removed, it must be discarded and replaced with
a brand new governor gear.
5. Using two flat screwdrivers, carefully pry
under governor gear (D) to remove from
spindle.
6. Remove cam gear from governor gear to
remove the spindle.
Inspect Governor Parts
1. Check oil slinger assembly for chipped or
damaged teeth, or damage on paddles. If
damage to the oil slinger is found, replace
the entire sump.
2. Check governor crank for wear or
damage. Replace if necessary.
3. Inspect cam gear for worn or damaged
teeth and evidence of wear on cam lobe.
Replace if necessary.
37
5
Assemble Governor
1. Install governor crank from inside cylinder.
Slide washer on crank and install new
push nut or clip.
2. Install governor gear on spindle in sump.
Using thumbs, press firmly until gear clicks
into place.
3. Align dot on timing gear with notch in cam
gear and place cam gear on boss in
cylinder (Inset, Figure 5-1).
4. Slide governor lever on crank and fingertighten bolt and nut until crank turns with
slight resistance.
4
5. Rotate crank so that paddle will be aligned
with cup on governor gear when sump is
installed.
6. Install new sump gasket of same thickness
as originally removed from cylinder.
7. Place seal protector in oil seal and slide
sump over crankshaft until it seats.
8. Install sump screws in order shown (E).
Torque screws to values listed in Section
12 - Engine Specifications.
5
9. Rotate crankshaft by hand to check for
binding then adjust governor system per
Section 1.
38
SECTION 6 - CYLINDER HEAD AND VALVES
CYLINDER HEAD AND VALVES - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -40
REMOVE CYLINDER HEAD - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -41
DISASSEMBLE - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -41
INSPECTION - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -41
ASSEMBLE - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -41
INSTALL CYLINDER HEAD - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -41
6
6
39
CYLINDER HEAD AND VALVES
6
6
Figure 6 - 1
40
Before the cylinder head can be removed, other
external parts must be removed, such as the air
cleaner, fuel tank, oil fill tube, blower housing,
muffler, carburetor, control bracket assembly,
and intake manifold.
Remove Cylinder Head
1. Remove spark plug.
2. Remove four screws (A, Figure 6-1) from
valve cover then remove cover (B) and
gasket (C). Discard gasket.
3. Remove cylinder head screws (D), then
remove head (E) and gasket (F) from
cylinder. Discard gasket.
Disassemble
1. Remove the retaining pin and the intake
and exhaust levers (G).
2. Place a clean shop rag (L) under the
cylinder head to hold valves in place while
compressing spring.
Assemble
1. Lightly coat valve stems with Valve Guide
Lubricant #93963, then insert valves into
cylinder head. Do not get lubricant on
valve face, valve seat, or exposed end of
valve stem.
2. Oil inside diameter of new stem seal and
install on intake valve stem. Slide seal
down against the cylinder head.
3. Support valve side of cylinder head on
clean shop rags. Place valve springs and
valve spring retainers over valve stems.
Using thumbs, press against each retainer
until it securely locks into groove in valve
stem.
Install Cylinder Head
1. Using new head gasket, install cylinder
head on cylinder and start screws by
hand.
2. Step-torque screws in sequence shown
(K) to values listed in Section 12 - Engine
Specifications.
3. Using thumb pressure, compress valve
spring retainer until larger hole (H) of
retainer fits over valve stem.
3. Install intake and exhaust levers with
retaining pin.
4. Remove retainer, spring, valve, and valve
seal (J).
4. Rotate crankshaft at least twice to ensure
proper movement of the levers and valves.
5. Repeat for other valve.
5. Adjust valve clearance per Section 1, then
install a new valve cover gasket and the
valve cover. Torque screws to values
listed in Section 12 - Engine
Specifications.
6. Using a plastic scraping tool, carefully
clean all traces of head gasket from the
head and cylinder mating surfaces.
6
6
Inspection
1. Visually inspect cylinder head for cracks,
excessive heat discoloration, warping, and
burned or damaged valve seats. Replace
head, if any of these problems are found.
2. Inspect valves for wear or damage.
Replace if necessary.
3. Oil the intake valve stem then insert valve
into head.
4. Using Valve Lapping Tool #19258 and
Lapping Compound #94150, lap valve and
seat together to assure a good sealing
surface. Remove valve, then repeat
procedure for the exhaust valve.
5. Thoroughly clean both valves and valve
seats of all lapping compound residue.
41
6
6
42
SECTION 7 - STARTERS
ELECTRIC STARTER- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -44
RING GEAR- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -45
DISASSEMBLE STARTER DRIVE- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -45
CHECK STARTER DRIVE OPERATION - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -45
ASSEMBLE STARTER DRIVE - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -45
REWIND STARTER - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -46
7
INSPECT REWIND STARTER PARTS- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -47
REPLACE ROPE - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 47
7
43
ELECTRIC STARTER
7
7
Figure 7 - 1
44
12 Volt Starter
Ring Gear
The ring gear on this engine is made of steel and
is heat shrunk to the flywheel. It is not repairable.
If the ring gear is damaged, replace the flywheel
assembly.
Check Starter Drive Operation
When the starter switch is activated, the starter
gear should engage the flywheel ring gear and
crank the engine. The starter gear should not
bind on the helix. If necessary, use a mild solvent
to clean the starter gear and helix. Dry with
compressed air.
NOTE: Do not oil the starter gear or helix.
Inspect Starter Parts
1. Inspect drive gear and pinion gear for
worn or broken teeth. Replace if
necessary.
2. Inspect starter gear and helix for wear or
scoring from dirt. Replace if necessary.
Assemble Starter Drive
1. Install gasket, pinion gear and drive gear
to the starter motor. Apply liberal amount
of grease to gear teeth.
2. Install felt washer.
7
3. Install cover and screws and torque to
values listed in Section 12 - Engine
Specifications.
4. Insert helix into starter gear and install
through cover and into drive gear.
5. Install new e-ring.
If the starter gear still binds on the helix, replace
the entire starter drive assembly using the
following procedures.
6. Position starter on cylinder and install
screws. Torque to values listed in Section
12 - Engine Specifications. Connect wire
harness.
Disassemble Starter Drive
1. Disconnect wire harness and remove
screws and starter motor from cylinder.
2. Carefully pry off and discard e-ring (A,
Figure 7-1).
7
3. Remove helix (C) from starter gear (D) by
rotating helix back and forth while pulling.
4. Remove three screws (B) that secure the
cover (E) to the starter drive assembly.
5. Remove and discard felt washer (F).
Disassemble the drive gear (G), pinion
gear (H), and gasket (J). Do not discard
the gasket or washer.
NOTE: The felt washer and gasket are not
serviceable parts.
45
REWIND STARTER
7
7
Figure 7 - 2
46
The rewind starter mechanism installed on this
engine is non-serviceable. The rope and handle
are the only serviceable parts.
Inspect Rewind Starter Parts
1. Remove fasteners (A, Figure 7-2) and lift
static guard/rewind assembly (B) off
blower housing.
2. Inspect the starter assembly for wear or
burrs at the rope eyelet, the center pivot
post, and the anchor tab. If damage is
found, replace the static guard/rewind
assembly.
7
Figure 7 - 5
3. Inspect the rope for broken or frayed
areas. Replace rope, if necessary.
Replace Rope
NOTE: Consult the Illustrated Parts List or
Section 12 - Engine Specifications for the correct
diameter and length of rope.
Figure 7 - 6
1. Hold rewind assembly firmly (A, Figure73) and pull out rope (B) until pulley stops.
NOTE: Spring tension in pulley will increase as
rope is pulled out.
2. Line up holes (C, Figure 7-4) of rewind
pulley and rope eyelet and secure pulley
assembly with small screwdriver (D).
Figure 7 - 3
3. Cut through middle of rope then remove
pieces from pulley and handle.
4. Insert one end of new rope into handle and
tie a knot (E, Figure 7-5) to secure it.
5. Insert other end of rope through eyelet and
hole in pulley (F). Tie a knot to secure the
rope, then fit knot into recess in pulley.
6. Hold rope firmly (G, Figure 7-6) while
removing screwdriver (H) then slowly
allow rope to rewind itself on pulley.
7. Place static guard/rewind assembly on
blower housing and install fasteners.
Torque to value listed in Section 12 Engine Specifications.
Figure 7 - 4
47
7
7
7
48
SECTION 8 - LUBRICATION
LUBRICATION SYSTEM- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -50
OIL FILL TUBE AND DIPSTICK- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -51
BREATHER - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -51
OIL SLINGER LUBRICATION - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -51
4
8
49
LUBRICATION SYSTEM
4
8
Figure 8 - 1
50
Oil Fill Tube and Dipstick
Oil Slinger Lubrication
This engine uses a plastic extended oil fill tube
(A, Figure 8-1) and a quarter-turn dipstick with oring (B). An o-ring (C) seals the tube in the sump
and a retaining bracket (D) and screw secure it to
the engine.
The oil fill tube and dipstick must be replaced as
a set.
The governor gear/oil slinger (J) is used on
vertical shaft engines. It is mounted to the sump
and driven by the cam gear.
Breather
Briggs & Stratton engines utilize a breather valve
system to control and maintain crankcase
vacuum. The breather valve installed on this
engine is a reed which closes on the piston up
stroke and opens on the piston down stroke.
Inspect Assembly
1. Visually inspect governor gear/oil slinger
assembly for wear, broken teeth, broken
slinger paddles, or burrs.
2. Ensure governor gear and slinger rotate
freely. Check for worn weight pins, worn
cup, or sticking weights.
3. The governor gear can be replaced, but if
there is damage to the oil slinger, the
entire sump must be replaced as an
assembly.
4
Remove Breather
1. Remove breather tube (E) from breather
cover (F).
2. Remove two screws (G), breather cover,
and gasket. Discard gasket.
Check Breather
1. Remove and check breather reed (H). If
the reed is worn or bent it cannot function
properly and must be replaced.
2. Inspect the oil-drain back hole in the
breather cavity. Insert a fine wire to ensure
the opening is not plugged.
8
Install Breather
1. Install reed with the metal tab facing away
from the crankshaft. Torque screw to
value listed in Section 12 - Engine
Specifications.
2. Using new gasket, install breather cover
and torque screws to values listed in
Section 12 - Engine Specifications.
3. Securely install breather tube in breather
cover.
51
4
8
52
SECTION 9 - CYLINDER AND SUMP
CYLINDER AND SUMP - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -54
INSPECT CYLINDER - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -55
INSPECT SUMP - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -56
MAIN BEARINGS - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -56
OIL SEALS - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -56
4
9
53
CYLINDER AND SUMP
4
9
Figure 9 - 1
54
Inspect Cylinder
1. Remove oil seal and discard. Using a
plastic scraper, remove all traces of head
gasket and sump gasket material.
• Visually check cylinder for cracks,
stripped threads, and bore damage.
Bore damage, if not severe, may be
corrected by reconditioning or resizing.
• If cracks are found, replace the cylinder.
• Stripped threads can sometimes be
repaired using a helicoil, but if multiple
holes have thread damage, replace the
cylinder.
2. Using a straight edge, check across
cylinder head mounting surface for
distortion (A, Figure 9-1). If mounting
surface is distorted more than 0.004”
(0.1mm), the cylinder must be replaced.
• Using Telescoping Gauge #19485 and
Dial Caliper #19199, measure the
diameter of the bore.If necessary,
recondition or resize the bore as
described below.
• Take two measurements (90° apart) at
the top, center, and bottom of the piston
ring travel (B).
• Compare measurements to the standard
cylinder bore size provided in Section 12
- Engine Specifications.
Reconditioning Bore
If cylinder bore is within specification and shows
no signs of scoring or other damage, it can be
reconditioned using a rigid hone with finishing
stones to restore the proper crosshatch angle.
The correct crosshatch of approximately 45° (C)
ensures proper lubrication and piston ring breakin.
Resizing Bore
If the cylinder bore is worn more than 0.003”
(0.08 mm) oversize, or is 0.0015” (.04 mm) out of
round, it must be resized.
Always resize to exactly 0.020” (.51 mm) larger
than standard bore size. Done accurately, the
service oversize rings and pistons will fit perfectly
with proper clearances.
Use the stones and lubrication recommended by
the hone manufacturer to produce the proper
sizing and finish.
4
NOTE: IT IS MOST IMPORTANT THAT THE
ENTIRE CYLINDER BE THOROUGHLY
CLEANED AFTER HONING.
Cleaning Cylinder
1. Wash the cylinder thoroughly with
kerosene or other commercial solvent.
2. Wash cylinder again using a stiff brush
with soap and hot water.
3. Rinse cylinder thoroughly with hot running
water.
4. Repeat washing and rinsing until all traces
of honing grit are gone.
NOTE: Honing grit is highly abrasive and will
cause rapid wear to all of the internal
components of the engine.
When cylinder has been thoroughly cleaned, use
a clean white rag to wipe the cylinder bore. If
honing grit is still present, it will appear as a grey
residue on the rag. Re-wash and rinse entire
cylinder, then check again. When there is no
trace of honing grit on the rag, the cylinder is
properly cleaned. Oil the cylinder bore to protect
the surface.
NOTE: IT IS MOST IMPORTANT THAT THE
ENTIRE CYLINDER BE THOROUGHLY
CLEANED AFTER HONING.
55
9
Inspect Sump
1. Remove oil seal and discard.
2. Visually inspect sump for cracks, stripped
threads, and wear in bearing surfaces. If
damage is found, replace the sump.
Oil Seals
Cylinder
Press in new oil seal to a depth of 0.156 - 0.206
in. (3 - 5mm) (Figure 9-2).
Cleaning Sump
1. Wash the sump thoroughly with kerosene
or other commercial solvent.
2. Wash sump again using a stiff brush with
soap and hot water.
3. Rinse sump thoroughly with hot running
water.
4
4. Repeat washing and rinsing until all traces
of oil sludge are gone.
Main Bearings
Figure 9 - 2
Plain Bearings
Plain (or machined) bearings are not repairable.
If a plain bearing is scored or worn beyond reject
its size, the cylinder or cover/sump must be
replaced.
Sump
Press in new oil seal to a depth of 0.157 - 0.276
in. (4 - 7 mm) (Figure 9-3).
DP™Bearings
DP™ bearings are not repairable. If a DP™
bearing is scored or worn beyond its reject size,
the cylinder or cover/sump must be replaced.
9
NOTE: Standard and reject sizes for the main
bearings are listed in Section 12 - Engine
Specifications.
56
Figure 9 - 3
SECTION 10 - CRANKSHAFT
CRANKSHAFT- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -58
REMOVE CRANKSHAFT - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -59
INSPECT CRANKSHAFT - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -59
INSTALL CRANKSHAFT- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -59
INSTALL SUMP - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -59
CHECK AND ADJUST CRANKSHAFT END PLAY - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -59
4
10
57
CRANKSHAFT
4
10
Figure 10 - 1
58
Remove Crankshaft
1. Drain oil from engine and all fuel from fuel
tank into appropriate container.
2. Remove external components including
flywheel assembly.
3. Remove burrs and clean crankshaft PTO,
then remove sump.
4. Carefully tip engine with PTO-end facing
up.
5. Rotate crankshaft to place piston at top
dead center.
Install Sump to Cylinder
1. Insert correct seal protector from Kit
#19356, to protect oil seal when installing
sump.
2. Place new gasket on cylinder.
3. Install sump on cylinder, making sure
spindle in sump fits into cam gear, and all
gears mesh. Do not force sump.
4. Install screws and tighten in sequence
shown (E). Torque screws to values listed
in Section 12 - Engine Specifications.
6. Remove connecting rod cap, then rotate
and slide out crankshaft.
Inspect Crankshaft
1. Inspect crankshaft for scoring on mag
journal (A, Figure 10-1), crankpin journal
(B), and PTO journal (C). Replace
crankshaft if scoring is found.
2. If crankshaft is bent, replace it. DO NOT
attempt to straighten crankshafts.
3. Using a dial caliper or micrometer,
measure the journal diameters. Compare
results to values listed in Section 12 Engine Specifications. If wear meets or
exceeds the reject dimensions, replace
the crankshaft.
4
Check and Adjust Crankshaft End
Play
When the sump is installed with a standard
gasket, end play should match the value listed in
Section 12 - Engine Specifications.
If end play is less than specified, remove sump
and install an additional gasket. Do not use more
than two gaskets.
If end play is more than specified, remove sump
and install a shim per the Illustrated Parts List.
Install shim on PTO-end of crankshaft (E),
between timing gear and sump.
4. Inspect timing gear for any evidence of
wear, distortion, or damage. Replace gear
if any damage is found.
Install Crankshaft
1. Lubricate the magneto bearing/oil seal
with engine oil.
2. Support both ends of the crankshaft, and
carefully install into the cylinder.
10
3. Rotate crankshaft until crankpin journal fits
into connecting rod.
4. Lubricate the crankpin journal with engine
oil, then assemble connecting rod to
crankshaft and torque cap screws to
values listed in Section 12 - Engine
Specifications.
NOTE: The screw closer to the piston must be
tightened first.
5. Install the timing gear to the crankshaft.
6. Align timing marks on timing gear and cam
gear (D), then install cam gear on boss in
cylinder.
59
4
10
60
SECTION 11 - PISTON, RINGS, AND CONNECTING ROD
PISTON, RINGS, AND CONNECTING ROD- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -62
REMOVE PISTON AND CONNECTING ROD- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -63
DISASSEMBLE - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -63
INSPECT- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -63
ASSEMBLE - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -64
4
11
61
PISTON, RINGS, AND CONNECTING ROD
4
11
Figure 11 - 1
62
Remove Piston and Connecting Rod
1. Carefully remove any carbon or ridge at
top of cylinder bore (A, Figure 11-1) to
prevent ring breakage.
2. Remove rod bolts (B) and connecting rod
cap (C).
5. Repeat procedure for wiper ring groove
and oil control ring groove.
6. Compare with reject dimensions listed in
Section 12 - Engine Specifications. If
clearance meets or exceeds the reject
dimensions, replace the piston.
3. Push piston (D) and connecting rod (E) out
through top of bore.
Disassemble
1. Using pliers, rotate piston pin clip (F) until
one end is exposed in notch in pin bore
(G), then remove clip.
4
2. Slide out piston pin (H) and remove
connecting rod from piston.
3. Using Piston Ring Expander #19340,
remove the compression ring (J) and the
wiper ring (K).
NOTE: Identify the top side of each ring before
removal.
4. The oil control rings (L) consist of two thin
steel rails and a spring expander. These
must be removed by hand as follows:
• Grasp one end of the upper steel rail and
wind the rail from the oil ring groove into
the center ring groove. Repeat into top
ring groove and then off the piston.
• Remove the spring expander then
remove the lower steel rail.
Inspect
Check Piston and Pin
1. Inspect piston for scoring, galling, or other
damage. Replace piston if necessary.
2. Using a dial caliper or plug gauge,
measure the pin bore diameter in the
piston. Compare with reject dimensions
listed in Section 12 - Engine
Specifications. If pin bore meets or
exceeds reject dimension, replace the
piston.
3. Measure outside diameter of pin and
compare to the reject dimensions listed in
Section 12 - Engine Specifications. If pin
meets or exceeds the reject dimension,
replace the pin.
4. Clean any carbon from the top ring groove
in piston. Place NEW ring in groove and,
using a feeler gauge, measure the
clearance between ring and ring land
(Figure 11-2).
Figure 11 - 2
Check Connecting Rod
If either the crankpin bearing or the piston pin
bearing is scored or discolored, the rod must be
replaced.
1. Reinstall rod cap and bolts on rod. Tighten
bolts until snug.
2. Using a dial caliper or plug gauge,
measure the two bearing diameters.
Compare with reject dimensions listed in
Section 12 - Engine Specifications. If
either bearing meets or exceeds its reject
dimension, the rod must be replaced.
3. Remove rod bolts and rod cap. Set aside.
Check Ring End Gap
It is recommended that the entire ring set be
replaced when servicing the piston and/or
cylinder bore. However, the original rings can be
re-used if they are not damaged and are
checked as follows:
63
11
1. Clean all carbon from the rings and the
cylinder bore.
NOTE: The notch or arrow on the piston and
“MAG” on the rod must face the same direction.
2. Insert one of the original rings
approximately one inch down the cylinder
bore.
3. Measure the ring end gap with a feeler
gauge (Figure 11-3).
4. Repeat the procedure for each ring in the
set.
5. Compare with reject dimensions listed in
Section 12 - Engine Specifications. If gap
of any of the rings meets or exceeds the
reject dimensions, all rings should be
replaced as a set.
4
11
Figure 11 - 3
Assemble
1. Install a pin retainer clip into one groove in
the pin bore.
2. Oil the piston pin bore, connecting rod pin
bearing, and the pin. Insert rod into piston,
then slip pin through piston and rod until it
seats against the retainer.
64
3. Install a pin retainer clip into groove on
open side of piston pin bore. Ensure both
retainers are firmly seated in the grooves.
4. Install the oil ring by hand as follows:
• Grasp one end of lower steel rail and
wind it over the top ring groove, then over
the center ring groove, and finally into the
oil ring groove.
• Install the spring expander on top of the
lower rail, then install the upper steel rail.
5. Using Piston Ring Expander #19340,
install the wiper ring, then the
compression ring.
NOTE: If installing the original rings, ensure the
top sides are facing the top of the piston. If
installing a new ring set, follow the instructions
provided with the set.
Install Piston and Connecting Rod
1. Thoroughly clean and oil cylinder bore and
crankpin journal of crankshaft.
4
2. Rotate crankshaft until crankpin journal is
at bottom of stroke.
3. Using Ring Compressor Tool #19070 or
#19230, install piston with notch or arrow
toward flywheel side of engine, taking care
not to damage crankpin journal or
connecting rod bearing.
4. Fit connecting rod bearing on crankpin
journal, then install rod cap with match
marks aligned. Cap should snap into
position when assembled correctly.
5. Install rod screws. Tighten screw closer to
the piston first, and the screw farther from
the piston second. Torque screws to
values listed in Section 12 - Engine
Specifications.
NOTE: Failure to use a torque wrench can result
in loose rods causing breakage, or overtightened rods causing scoring.
6. Rotate crankshaft two revolutions to
ensure crankpin and rod do not bind, then
move connecting rod sideways to ensure
there is clearance on crankpin. If binding
occurs, remove and reinstall the rod cap.
11
65
4
11
66
SECTION 12 - ENGINE SPECIFICATIONS
MODEL 090600 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -68
MODEL 100600 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -70
MODEL 100800 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -72
12
67
ENGINE SPECIFICATIONS
MODEL 090600
ENGINE SPECIFICATIONS
Alternator Air Gap
Armature Air Gap
Crankshaft End Play
Spark Plug Gap
Valve Clearance – Intake
Valve Clearance – Exhaust
FASTENER TORQUE SPECIFICATIONS
Air Cleaner Base
Air Cleaner Cover
Alternator
Armature
Blower Housing
Breather Cover
Breather Reed
Bowl Nut
Carburetor to Cylinder Head
Casing Clamp
Connecting Rod
Control Bracket
Control Panel Trim
Crankcase Sump
Cylinder Head
Flywheel Brake Assembly
Flywheel Guard
Flywheel Nut
Fuel Tank
Governor Lever Nut
Muffler
Muffler Guard
Muffler Deflector
Oil Drain Plug
Rewind Assembly/Static Guard
Spark Plug
Starter Motor Bracket
Starter Drive Cover
Valve Cover
Valve Clearance Nut
12
68
.006 - .014 in. (.15 - .33 mm)
.006 - .014 in. (.15 - .33 mm)
.002 - .038 in. (.05 - .97 mm)
.020 in. (.51 mm)
.004 - .006 in. (.10 - .15 mm)
.014 - .016 in. (.36 - .41 mm)
TORQUE
45 lb-in. (5 Nm)
12 lb-in. (1 Nm)
55 lb-in. (6 Nm)
85 lb-in. (10 Nm)
85 lb-in. (10 Nm)
55 lb-in. (6 Nm)
45 lb-in. (5 Nm)
90 lb-in. (10 Nm)
85 lb-in. (10 Nm)
20 lb-in. (2 Nm)
95 lb-in. (11 Nm)
95 lb-in. (11 Nm)
40 lb-in. (5 Nm)
110 lb-in. (12 Nm)
210 lb-in. (24 Nm)
45 lb-in. (5 Nm)
45 lb-in. (5 Nm)
60 lb-ft. (81 Nm)
85 lb-in. (10 Nm)
30 lb-in. (3 Nm)
85 lb-in. (10 Nm)
45 lb-in. (5 Nm)
15 lb-in. (2 Nm)
145 lb-in. (16 Nm)
30 lb-in (3 Nm)
180 lb-in. (20 Nm)
85 lb-in. (10 Nm)
20 lb-in. (2 Nm)
55 lb-in. (6 Nm)
20 lb-in. (2 Nm)
REJECT DIMENSIONS
CYLINDER
Main Bearing
Bore Diameter
Bore Out-Of-Round
CYLINDER HEAD
Valve Guide
Intake Valve Stem Diameter
Exhaust Valve Stem Diameter
CYLINDER COVER / SUMP
PTO Bearing
CRANKSHAFT
Crank Pin Journal
Mag-Side Journal
PTO-Side Journal
CONNECTING ROD
Crank Pin Bearing
Piston Pin Bearing
PISTON
Piston Pin
Piston Pin Bearing
Ring End Gap (Top)
Ring End Gap (Middle)
Ring End Gap (Oil Control)
Ring Land Clearance (Top)
Ring Land Clearance (Middle)
Ring Land Clearance (Oil Control)
STARTER ROPE
Rope Size
Rope Length
STANDARD SIZE
REJECT SIZE
.876 in. (22.25 mm)
2.520 in. (64.00 mm)
N/A
.878 in. (22.30 mm)
2.525 in. (64.14 mm)
.0015 in. (.04 mm)
.200 in. (5.08 mm)
.197 in. (5.00 mm)
.196 in. (4.98 mm)
.203 in. (5.16 mm)
.197 in. (5.08mm)
.196 in. (5.05mm)
1.065 in. (27.05 mm)
1.066 in. (27.08 mm)
1.098 in. (27.89 mm)
.874 in. (22.20 mm)
1.061 in. (26.96 mm)
1.097 in. (27.86 mm)
.873 in. (22.17 mm)
1.060 in. (26.92 mm)
1.100 in. (27.94 mm)
.491 in. (12.47 mm)
1.102 in. (27.99 mm)
.493 in. (12.52 mm)
.490 in. (12.45 mm)
.491 in. (12.47 mm)
.004 - .010 in. (.10 - .25 mm)
.017 - .023 in. (.43 - .58 mm)
.017 - .023 in. (.43 - .58 mm)
.002 - .006 in. (.05 - .15 mm)
.002 - .006 in. (.05 - .15 mm)
.002 - .006 in. (.05 - .15 mm)
.489 in. (12.42 mm)
.493 in. (12.49 mm)
.020 in. (.15 mm)
.030 in. (.76 mm)
.035 in. (.89 mm)
.008 in. (.20 mm)
.008 in. (.20 mm)
.008 in. (.20 mm)
#4 (3.18 mm)
88-5/8 in. (2.2 m)
N/A
N/A
12
69
MODEL 100600
ENGINE SPECIFICATIONS
Alternator Air Gap
Armature Air Gap
Crankshaft End Play
Spark Plug Gap
Valve Clearance – Intake
Valve Clearance – Exhaust
FASTENER TORQUE SPECIFICATIONS
Air Cleaner Base
Air Cleaner Cover
Alternator
Armature
Blower Housing
Breather Cover
Breather Reed
Bowl Nut
Carburetor to Cylinder Head
Casing Clamp
Connecting Rod
Control Bracket
Control Panel Trim
Crankcase Sump
Cylinder Head
Flywheel Brake Assembly
Flywheel Guard
Flywheel Nut
Fuel Tank
Governor Lever Nut
Muffler
Muffler Guard
Muffler Deflector
Oil Drain Plug
Rewind Assembly/Static Guard
Spark Plug
Starter Motor Bracket
Starter Drive Cover
Valve Cover
Valve Clearance Nut
12
70
.006 - .014 in. (.15 - .33 mm)
.006 - .014 in. (.15 - .33 mm)
.002 - .038 in. (.05 - .97 mm)
.020 in. (.51 mm)
.004 - .006 in. (.10 - .15 mm)
.014 - .016 in. (.36 - .41 mm)
TORQUE
45 lb-in. (5 Nm)
12 lb-in. (1 Nm)
55 lb-in. (6 Nm)
85 lb-in. (10 Nm)
85 lb-in. (10 Nm)
55 lb-in. (6 Nm)
45 lb-in. (5 Nm)
90 lb-in. (10 Nm)
85 lb-in. (10 Nm)
20 lb-in. (2 Nm)
95 lb-in. (11 Nm)
95 lb-in. (11 Nm)
40 lb-in. (5 Nm)
110 lb-in. (12 Nm)
210 lb-in. (24 Nm)
45 lb-in. (5 Nm)
45 lb-in. (5 Nm)
60 lb-ft. (81 Nm)
85 lb-in. (10 Nm)
30 lb-in. (3 Nm)
85 lb-in. (10 Nm)
45 lb-in. (5 Nm)
15 lb-in. (2 Nm)
145 lb-in. (16 Nm)
30 lb-in (3 Nm)
180 lb-in. (20 Nm)
85 lb-in. (10 Nm)
20 lb-in. (2 Nm)
55 lb-in. (6 Nm)
20 lb-in. (2 Nm)
REJECT DIMENSIONS
CYLINDER
Main Bearing
Bore Diameter
Bore Out-Of-Round
CYLINDER HEAD
Valve Guide
Intake Valve Stem Diameter
Exhaust Valve Stem Diameter
CYLINDER COVER / SUMP
PTO Bearing
CRANKSHAFT
Crank Pin Journal
Mag-Side Journal
PTO-Side Journal
CONNECTING ROD
Crank Pin Bearing
Piston Pin Bearing
PISTON
Piston Pin
Piston Pin Bearing
Ring End Gap (Top)
Ring End Gap (Middle)
Ring End Gap (Oil Control)
Ring Land Clearance (Top)
Ring Land Clearance (Middle)
Ring Land Clearance (Oil Control)
STARTER ROPE
Rope Size
Rope Length
STANDARD SIZE
REJECT SIZE
.876 in. (22.25 mm)
2.520 in. (64.00 mm)
N/A
.878 in. (22.30 mm)
2.525 in. (64.14 mm)
.0015 in. (.04 mm)
.200 in. (5.08 mm)
.197 in. (5.00 mm)
.196 in. (4.98 mm)
.203 in. (5.16 mm)
.197 in. (5.08mm)
.196 in. (5.05mm)
1.065 in. (27.05 mm)
1.066 in. (27.08 mm)
1.098 in. (27.89 mm)
.874 in. (22.20 mm)
1.061 in. (26.96 mm)
1.097 in. (27.86 mm)
.873 in. (22.17 mm)
1.060 in. (26.92 mm)
1.100 in. (27.94 mm)
.491 in. (12.47 mm)
1.102 in. (27.99 mm)
.493 in. (12.52 mm)
.490 in. (12.45 mm)
.491 in. (12.47 mm)
.004 - .010 in. (.10 - .25 mm)
.017 - .023 in. (.43 - .58 mm)
.017 - .023 in. (.43 - .58 mm)
.002 - .006 in. (.05 - .15 mm)
.002 - .006 in. (.05 - .15 mm)
.002 - .006 in. (.05 - .15 mm)
.489 in. (12.42 mm)
.493 in. (12.49 mm)
.020 in. (.15 mm)
.030 in. (.76 mm)
.035 in. (.89 mm)
.008 in. (.20 mm)
.008 in. (.20 mm)
.008 in. (.20 mm)
#4 (3.18 mm)
88-5/8 in. (2.2 m)
N/A
N/A
12
71
MODEL 100800
ENGINE SPECIFICATIONS
Alternator Air Gap
Armature Air Gap
Crankshaft End Play
Spark Plug Gap
Valve Clearance – Intake
Valve Clearance – Exhaust
FASTENER TORQUE SPECIFICATIONS
Air Cleaner Base
Air Cleaner Cover
Alternator
Armature
Blower Housing
Breather Cover
Breather Reed
Bowl Nut
Carburetor to Cylinder Head
Casing Clamp
Connecting Rod
Control Bracket
Control Panel Trim
Crankcase Sump
Cylinder Head
Flywheel Brake Assembly
Flywheel Guard
Flywheel Nut
Fuel Tank
Governor Lever Nut
Muffler
Muffler Guard
Muffler Deflector
Oil Drain Plug
Rewind Assembly/Static Guard
Spark Plug
Starter Motor Bracket
Starter Drive Cover
Valve Cover
Valve Clearance Nut
12
72
.006 - .014 in. (.15 - .33 mm)
.006 - .014 in. (.15 - .33 mm)
.002 - .038 in. (.05 - .97 mm)
.020 in. (.51 mm)
.004 - .006 in. (.10 - .15 mm)
.014 - .016 in. (.36 - .41 mm)
TORQUE
45 lb-in. (5 Nm)
12 lb-in. (1 Nm)
55 lb-in. (6 Nm)
85 lb-in. (10 Nm)
85 lb-in. (10 Nm)
55 lb-in. (6 Nm)
45 lb-in. (5 Nm)
90 lb-in. (10 Nm)
85 lb-in. (10 Nm)
20 lb-in. (2 Nm)
95 lb-in. (11 Nm)
95 lb-in. (11 Nm)
40 lb-in. (5 Nm)
110 lb-in. (12 Nm)
210 lb-in. (24 Nm)
45 lb-in. (5 Nm)
45 lb-in. (5 Nm)
60 lb-ft. (81 Nm)
85 lb-in. (10 Nm)
30 lb-in. (3 Nm)
85 lb-in. (10 Nm)
45 lb-in. (5 Nm)
15 lb-in. (2 Nm)
145 lb-in. (16 Nm)
30 lb-in (3 Nm)
180 lb-in. (20 Nm)
85 lb-in. (10 Nm)
20 lb-in. (2 Nm)
55 lb-in. (6 Nm)
20 lb-in. (2 Nm)
REJECT DIMENSIONS
CYLINDER
Main Bearing
Bore Diameter
Bore Out-Of-Round
CYLINDER HEAD
Valve Guide
Intake Valve Stem Diameter
Exhaust Valve Stem Diameter
CYLINDER COVER / SUMP
PTO Bearing
CRANKSHAFT
Crank Pin Journal
Mag-Side Journal
PTO-Side Journal
CONNECTING ROD
Crank Pin Bearing
Piston Pin Bearing
PISTON
Piston Pin
Piston Pin Bearing
Ring End Gap (Top)
Ring End Gap (Middle)
Ring End Gap (Oil Control)
Ring Land Clearance (Top)
Ring Land Clearance (Middle)
Ring Land Clearance (Oil Control)
STARTER ROPE
Rope Size
Rope Length
STANDARD SIZE
REJECT SIZE
.876 in. (22.25 mm)
2.520 in. (64.00 mm)
N/A
.878 in. (22.30 mm)
2.525 in. (64.14 mm)
.0015 in. (.04 mm)
.200 in. (5.08 mm)
.197 in. (5.00 mm)
.196 in. (4.98 mm)
.203 in. (5.16 mm)
.197 in. (5.08mm)
.196 in. (5.05mm)
1.065 in. (27.05 mm)
1.066 in. (27.08 mm)
1.098 in. (27.89 mm)
.874 in. (22.20 mm)
1.061 in. (26.96 mm)
1.097 in. (27.86 mm)
.873 in. (22.17 mm)
1.060 in. (26.92 mm)
1.100 in. (27.94 mm)
.491 in. (12.47 mm)
1.102 in. (27.99 mm)
.493 in. (12.52 mm)
.490 in. (12.45 mm)
.491 in. (12.47 mm)
.004 - .010 in. (.10 - .25 mm)
.017 - .023 in. (.43 - .58 mm)
.017 - .023 in. (.43 - .58 mm)
.002 - .006 in. (.05 - .15 mm)
.002 - .006 in. (.05 - .15 mm)
.002 - .006 in. (.05 - .15 mm)
.489 in. (12.42 mm)
.493 in. (12.49 mm)
.020 in. (.15 mm)
.030 in. (.76 mm)
.035 in. (.89 mm)
.008 in. (.20 mm)
.008 in. (.20 mm)
.008 in. (.20 mm)
#4 (3.18 mm)
88-5/8 in. (2.2 m)
N/A
N/A
12
73
12
74