Briggs & Stratton 276535 Operating instructions

2-Cycle Snow Engine
0
2-CYCLE SNOW ENGINE
REPAIR MANUAL
MANUAL NUMBER: 276535

2-Cycle Snow Engine
i
SAFETY INFORMATION
The Briggs & Stratton engine is made of the finest
material in a state-of-the-art manufacturing facility.
Please understand that Briggs & Stratton sells engines
to original equipment manufacturers. It also sells to
others in the distribution chain who may sell to the
ultimate consumer, an equipment manufacturer, another
distributor or a dealer. As a result, Briggs & Stratton does
not necessarily know the application on which the engine
will be placed. For that reason, carefully read and
understand the operating instructions of the equipment
before you repair or operate.
You should also understand that there are equipment
applications for which Briggs & Stratton does not
approve the useof its engines. Briggs & Stratton engines
are not to be used on vehicles with less than 4 wheels.
This includes motor bikes, aircraft products and all
terrain vehicles. Moreover, Briggs & Stratton does not
approve of its engines being used in competitive events.
FOR THAT REASON, BRIGGS & STRATTON
ENGINES ARE NOT AUTHORIZED FOR ANY OF
THESE APPLICATIONS. Failure to follow this warning
could result in death, serious injury (including paralysis)
or property damage.
IN THE INTEREST OF SAFETY
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 indicates a hazard which, if not
avoided, could result in death or serious injury.
CAUTION indicates a hazard which, if not
avoided, might result in minor or moderate injury.
CAUTION: When this signal word is used without the
alert symbol, it indicates a situation that could result in
damage to the engine.
• Prior to work, read and understand the section(s) of
this manual that pertain to the job. Follow all safety
warnings.
• Wear suitable eye protection.
• Prevent accidental starting by removing spark plug
wire from spark plug when servicing engine or
equipment. Disconnect negative battery terminal if
equipped with electric starting system.
• Periodically clean engine. Keep governor parts free
of dirt, grass and other debris which can affect
engine speed.
• Always use fresh gasoline. Stale fuel can gum
carburetor and cause leakage.
• Check fuel lines and fittings frequently for cracks or
leaks and replace if necessary.

2-Cycle Snow Engine
ii

2-Cycle Snow Engine
iii

2-Cycle Snow Engine
Table of Contents
iv
2-CYCLE SNOW ENGINE
REPAIR MANUAL .....................................0
SAFETY INFORMATION ...........................i
In The Interest Of Safety ...............................i
SECTION 1
GENERAL INFORMATION .......................1
TWO-CYCLE ENGINE THEORY .................1
IGNITION COIL OPERATION ......................2
REWIND STARTER .....................................3
ELECTRIC START (OPTIONAL) .................3
RECOMMENDED MAINTENANCE
SCHEDULE ..................................................3
25 Hours ..........................................................3
50 Hours ..........................................................3
REPLACE SPARK PLUG .............................4
CLEANING THE EXHAUST SYSTEM .........4
SECTION 2
TROUBLESHOOTING ..............................5
GENERAL TROUBLESHOOTING
INFORMATION ............................................5
Systematic Check ............................................5
Check Ignition ..................................................5
Engine Misfires ................................................5
Check Carburetion ...........................................6
Check Compression ........................................6
EQUIPMENT AFFECTING ENGINE
OPERATION ................................................6
Hard Starting, Kickback, or Will Not Start ........7
Vibration ...........................................................7
Power Loss ......................................................7
STARTER MOTOR FAILS TO TURN .........7
Power not reaching product. ............................7
Starter switch malfunction. ...............................7
Engine has seized. ..........................................7
Starter motor has failed. ..................................7
SECTION 3
ENGINE DISASSEMBLY ..........................9
REMOVE SHROUD .....................................9
REMOVE CARBURETOR ............................9
REMOVE FLYWHEEL ................................10
REMOVE OPTIONAL 120V STARTER ......10
REMOVE MUFFLER ..................................10
REMOVE IGNITION MODULE ...................11
ENGINE DISASSEMBLY ...........................11
SECTION 4
ENGINE OVERHAUL ..............................13
ENGINE INSPECTION & REPAIR .............13
Flywheel and Key ...........................................13
Bearings .........................................................13
Crankcase ......................................................13
Check Cylinder Bore ......................................13
Piston And Rings ............................................14
Piston Pin (Wrist Pin) And Connecting Rod .....4
CARBURETOR DISASSEMBLY ................15
CARBURETOR CLEANING &
INSPECTION ..............................................17
CARBURETOR ASSEMBLY ......................17
REWIND STARTER Replacement .............20
Rope Replacement .........................................20
(OPTIONAL) ELECTRIC STARTER
REPLACEMENT .........................................20
SECTION 5
ENGINE ASSEMBLY ..............................21
ASSEMBLE PISTON AND
CONNECTING ROD ..................................21
INSTALL PISTON RINGS ..........................21
Engine Model 84130 & 84230 ........................21
Engine Model 84330 .....................................21

2-Cycle Snow Engine
Table of Contents
v
INSTALL PISTON AND
CONNECTING ROD ..................................22
INSTALL CONNECTING ROD BEARINGS 23
INSTALL CRANKSHAFT AND
CONNECTING ROD ..................................23
INSTALL OIL SEALS ..................................24
INSTALL CRANKCASE COVER ................25
INSTALL CYLINDER HEAD .......................25
INSTALL IGNITION COIL AND
FLYWHEEL ................................................25
INSTALL AIR VANE AND GOVERNOR .....26
INSTALL INTAKE MANIFOLD AND
CARBURETOR ..........................................27
CHECK GOVERNOR OPERATION ...........27
INSTALL MUFFLER ...................................28
INSTALL BLOWER HOUSING ...................28
SECTION 6
FINAL ADJUSTMENTS &
SPECIFICATIONS ..................................29
GOVERNOR ADJUSTMENTS ...................29
SPECIFICATIONS ......................................30
COMMON SPECIFICATIONS ....................30
STANDARD AND REJECT DIMENSIONS 31

2-Cycle Snow Engine
Section 1 - General Information
Page 1
SECTION 1
GENERAL INFORMATION
TWO-CYCLE ENGINE THEORY
In a piston-ported engine, the fuel mixture enters the
crankcase through a port that comes directly from the
carburetor (commonly referred to as a “third port”), See
item figure 1.
Fig. 1
At about 28° before top-dead-center (BTDC), the spark
plug ignites and forces the piston away from the spark
plug. As the piston moves away from the spark plug, it
exposes the exhaust port (Item Figure 2) and the
expanding exhaust gases escape. As the piston
continues to move away from the spark plug, it
compresses the fuel mixture (Item Figure 2) that is on
the bottom side of the piston in the crankcase.
Fig. 2
Near the bottom of its travel, the piston uncovers the
pressure transfer port and allows this compressed fuel/
air mixture to expand into the combustion chamber
(Item Figure 3).
Fig. 3
Now the piston begins its travel in the opposite direction
and first closes off the transfer port and then the exhaust
Intake Ports Closed
Ignition Third Port Open
Partial Vacuum
Intake Ports Closed
Exhaust Port Opening
Third Port Closed
Pressure Building Up
Intake Ports Open
Exhaust Port Open Fresh Fuel Change
Third Port Closed

2-Cycle Snow Engine
Section 1 - General Information
Page 2
port. As it continues, it compresses the fuel mixture in
the combustion chamber (Item Figure 4).
Fig. 4
IGNITION COIL OPERATION
The ignition coil system (Item Figure 5) is
breakerless and contains electronic components that
replace mechanical points and related accessories (such
as a breaker cam, spark advance assembly, etc.).
Fig. 5
As the flywheel magnet passes the ignition coil module,
an AC voltage is induced into the charge coil. This AC
voltage is converted by a rectifier into a DC signal, which
is then stored in a capacitor (Figure 6).
Fig. 6
When the silicone-controlled rectifier (SCR) is triggered,
up to 200 volts DC, stored in the capacitor, travels to the
spark coil. Here it is stepped up to as much as 25,000
volts and is discharged across the electrodes of the
spark plug (Figure 7).
Ignition timing (when the SCR is triggered) is determined
by the flywheel magnet and the keyways in the flywheel
and crankshaft. Damage to any of these parts will affect
the ignition timing.
Fig. 7
Intake Ports Closed
Compression
Third Port Closed
Partial Vacuum
Ignition Coil Module

2-Cycle Snow Engine
Section 1 - General Information
Page 3
At slower speeds, the flywheel magnet induces a smaller
charge in the trigger coil. This action triggers the (SCR),
enabling easier starting in a “retarded firing position”
-about 5° before top dead center (BTDC). See figure 8.
Fig. 8
At faster speeds (about 800 RPM), the flywheel magnets
induce a large enough charge in the trigger coil to trigger
the SCR in the “advanced firing position,” -about 28°
BTDC (Figure 9).
Fig. 9
REWIND STARTER
The rewind starter operates through a retainer/friction
disc and two engagement dogs that extend from the
center of the rewind starter and engage the inside of the
starter hub on the flywheel. The engagement dogs
contact the starter hub when the rewind rope is pulled.
When the engine starts, the starter cup exceeds the
speed of the recoil starter causing the ramps on the
inside of the cup to contact the back side of the starter
dogs, pushing them inward. When the starter rope is
relaxed, spring tension retracts the dogs.
ELECTRIC START (OPTIONAL)
The electric start models use a 120VDC starting system.
When the starter is supplied with voltage, the helical
shaft spins to force the pinion gear out on the shaft and
engage the ring gear (Figure 10).
Fig.10
RECOMMENDED MAINTENANCE
SCHEDULE
25 Hours
• Clean/replace or re-gap spark plug
50 Hours
• Clean exhaust ports
• Check for fuel leakage
Pole Shoe
Flywheel Rotation
Crankshaft at 5° BTDC
Magnet
Starting Leg
Charging Leg
Pole Shoe
Flywheel Rotation
Crankshaft at 25° BTDC
Charging Leg
Running Leg 25°
Advanced

2-Cycle Snow Engine
Section 1 - General Information
Page 4
REPLACE SPARK PLUG
Replace spark plug every year. Replace spark plug if
electrode is burned away or if the porcelain is cracked. A
spark plug that is dirty, pitted, carbon covered or has
worn electrodes may cause hard starting and/or poor
operation. Clean plug with a wire brush. Do not sand
blast. Use NGK BPMR 4A or equivalent. Set spark plug
gap (Figure 11) at .028-.032 in. (.71-.81mm). Torque spark
plug to 150-200 lb-in. (17-23 Nm).
Fig. 11
CLEANING THE EXHAUST SYSTEM
1. Remove the muffler (Figure 12) by removing the
bolts shown. Clean as needed.
Fig. 12
2. Inspect exhaust port (Figure 13). If cleaning is
necessary, rotate piston to cover exhaust port,
and scrape carbon from exhaust port area. Use
wood only to clean this area.
Fig. 13
3. Install the muffler and torque the bolts to 80 lb-in.
(9Nm).
.28-.032 in.
(.71 - .81mm)
BST01-82
BST01-83

2-Cycle Snow Engine
Section 2 - Troubleshooting
Page 5
SECTION 2
TROUBLESHOOTING
GENERAL TROUBLESHOOTING
INFORMATION
Most complaints concerning engine operation can be
classified as one or a combination of the following:
• Will not start
• Hard starting
• Lack of power
• Runs rough
• Vibration
NOTE: What appears to be an engine
malfunction may be a fault of the powered
equipment rather than the engine. If equipment is
suspect, see Equipment Affecting Engine
Operation.
Systematic Check
If the engine is hard starting or will not start and the
cause of malfunction is not readily apparent, perform a
systematic check in the following order:
• Ignition
• Carburetion
• Compression
This check-up, performed in a systematic manner, can
usually be done in a matter of minutes. It is the quickest
and surest method of determining the cause of failure.
Check Ignition
With stop switch in ON/RUN position and spark plug
installed, attach a #19368 ignition tester to the spark plug
lead and ground the other end of the tester as shown in
figure 14. Operate the starter. If a strong, steady spark is
observed at the tester gap, you may assume the ignition
system is functioning satisfactorily.
Fig. 14
NOTE: Engines equipped with capacitive
discharge ignition system will still display spark
at tester with a partially or fully sheared flywheel
key. A partially sheared flywheel key will affect
ignition timing and engine performance.
If spark does not occur look for:
• Shorted stop switch
• Shorted ground wire
• Incorrect armature air gap
• Armature failure
Engine Misfires
If engine runs but misses during operation, a quick check
to determine if ignition is or is not at fault can be made by
installing Tool #19368 tester between the spark plug lead
and spark plug (Figure 15). A spark miss will be obvious

2-Cycle Snow Engine
Section 2 - Troubleshooting
Page 6
when the engine is running. If the spark looks good in the
tester but the engine misses, try a new spark plug.
Fig. 15
NOTE: A leak at the cylinder crankcase
mounting surfaces or oil seals can create a lean
fuel mixture resulting in low power or a miss.
Check for leakage at these areas.
Check Carburetion
Before checking carburetion, be sure the fuel tank has
an ample supply of fresh, clean gasoline. Make sure
throttle and choke controls are properly adjusted.
If engine cranks but will not start, remove and inspect the
spark plug.
If plug is wet, look for:
• Over choking
• Water in fuel
• Float needle valve stuck open
• Fouled spark plug
If plug is dry, look for:
• Leaking carburetor mounting gaskets.
• Gummy or dirty carburetor, fuel filter, fuel lines or
fuel tank
• Float needle valve stuck shut
• Plugged fuel cap vent
A simple check to determine if the fuel is getting to the
combustion chamber through the carburetor is toremove
the spark plug and pour a small quantity of fuel
(1 teaspoon or 5 mil.) 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.
Check Compression
Connect spark plug wire to long terminal of tester, Tool
#19368 and ground tester to engine with alligator clip.
To check compression,remove the spark plug and install
compression tester (Figure 16).
Fig. 16
Crank the engine using the rewind starter. Continue
cranking until meter reading stabilizes. The meter
reading should be approximately 115 PSI. (7.9 bar). If
compression is below 80 PSI (5.5 bar), look for:
• Loose cylinder head bolts
• Blown head gasket
• Worn bore and/or rings
• Broken connecting rod
EQUIPMENT AFFECTING ENGINE
OPERATION
Frequently, what appears to be a problem with engine
operation, such as hard starting, vibration, etc., can be
caused by the equipment being powered rather than the
engine itself. Since many varied types of equipment are
powered by Briggs & Stratton engines, it is not possible
to list all of the various conditions that may exist. Listed
are the most common effects of equipment problems,
and what to look for as the most common cause.
WE NEED TO FIND A TESTER!

2-Cycle Snow Engine
Section 2 - Troubleshooting
Page 7
Hard Starting, Kickback, or Will Not Start
• Loose drive adapter(s) - Pulleys and adapters must
be tight to shaft. Also, check for partially sheared
flywheel key.
• Starting under load - ensure the unit is not engaged
when engine is started; if the unit is engaged, that it
does not pose an excessive load to the engine.
• Check choke for proper adjustment.
• Check interlock system (if equipped) for shorted
wires, loose or corroded connections, or defective
modules or switches.
Vibration
• Auger bent or out of balance.
• Worn drive pulley(s)
• Mounting bolts loose
• Check for partially sheared flywheel key.
Power Loss
• Bind or drag in unit - if possible, disengage engine
and operate unit manually to check for any binding
action.
STARTER MOTOR FAILS TO TURN
Power not reaching product.
• Plug another appliance into extension cord to
ensure cord is OK.
Starter switch malfunction.
• Check switch using a volt/ohmmeter set for
resistance. Ensure that there is continuity when the
switch is depressed.
Engine has seized.
• Verify that the engine turns over freely.
Starter motor has failed.
• If all the above conditions are checked and the
starter still fails to turn, it must be repaired or
replaced.

2-Cycle Snow Engine
Section 2 - Troubleshooting
Page 8

2-Cycle Snow Engine
Section 3 - Engine Disassembly
Page 9
SECTION 3
ENGINE DISASSEMBLY
REMOVE SHROUD
1. Disconnect spark plug wire.
2. Remove the two screws that attach the shroud
to the base (Figure 17).
3. Remove the nuts and washers from the studs
(Figure 17).
Fig. 17
REMOVE CARBURETOR
NOTE: We strongly recommend cleaning the
exterior of the carburetor before removal from
the engine.
1. Remove fuel line and drain; remove the fuel tank.
(On some snow throwers, it will be necessary to
remove the lower shroud to access the carburetor
and fuel line.)
2. Disconnect the primer tube from the carburetor
fitting and remove the choke cable.
3. Slide the air vane from its mounting bracket as
shown (Figure 18).
Fig. 18
4. Remove the two screws that secure the
carburetor to the intake pipe and discard the
gasket (Figure 19).
Fig. 19
5. Pull the carburetor assembly down and away from
the engine and set aside.
720-002

2-Cycle Snow Engine
Section 3 - Engine Disassembly
Page 10
REMOVE FLYWHEEL
1. Remove flywheel nut and starter cup (Figure 20).
Fig. 20
2. Reinstall nut flush with the end of the crankshaft.
3. Remove the flywheel by pulling up on the edge of
flywheel while striking the flywheel nut with a soft
mallet (Figure 21).
Fig. 21
4. Remove key.
REMOVE OPTIONAL 120V STARTER
1. Remove the starter switch, the bolt holding the
wire clip, and the two bolts which mount the
starter to the engine (Figure 22).
Fig. 22
REMOVE MUFFLER
1. Remove the two bolts that secure the muffler
to the cylinder (Figure 23).
Fig. 23
2. Remove muffler and discard gasket.
3. Remove muffler re-enforcement plate (if installed).
0893-21
l0893-34
1657-017

2-Cycle Snow Engine
Section 3 - Engine Disassembly
Page 11
REMOVE IGNITION MODULE
1. Remove the two bolts that hold the ignition
module to the head (Figure 24).
Fig. 24
ENGINE DISASSEMBLY
1. Remove the six crankcase cap screws
(Figure 25).
2. Carefully separate the crankcase cover and
cylinder using a screwdriver. Be careful not to
damage the sealing surfaces.
Fig. 25
3. Remove the entire crankshaft assembly and
discard the oil seals.
4. Carefully remove the cap screws (Figure 26).
5. Remove the connecting rod cap and the split
bearing liner.
Fig. 26
The needle roller bearings are under the split bearing
liner.
NOTE: Early engines do not have match marks
on the connecting rod cap. If there are no marks,
use a marker to index the cap to the connecting
rod.
6. Remove the piston and rod assembly. Separate
the assembly.
7. Use a snap ring pliers on the retaining rings and
remove the wrist pin (Figure 27).
Fig. 27
8. Use ring expander (#19340) and remove rings from
piston.
0720-013
0893-24b

2-Cycle Snow Engine
Section 3 - Engine Disassembly
Page 12
9. Remove the two studs and two nuts
(Figure 28) retaining the cylinder head to the
block. Remove the head and discard the head
gasket.
Fig. 28
720-008

2-Cycle Snow Engine
Section 4 - Engine Overhaul
Page 13
SECTION 4
ENGINE OVERHAUL
ENGINE INSPECTION & REPAIR
Flywheel and Key
1. Check the condition of the flywheel key and
keyway to ensure that is not partially sheared,
galled or distorted (Figure 29).
Fig. 29
2. Inspect the flywheel for cracks or damage.
Replace as necessary (Figure 30).
Fig. 30
NOTE: Replace crankshaft and/or flywheel if
keyway is distorted or cracked in any way.
Bearings
1. Check ball bearings for wear and freedom of
movement; replace if questionable.
Crankcase
1. Inspect the crankcase for cracks or any other
indication of damage.
2. Clean crankcase surfaces with a commercial
gasket remover (Figure 31).
Fig. 31
Check Cylinder Bore
1. Check cylinder bore for wear using telescoping
gauge (#19404) and dial caliper (#19199).
2. Measure cylinder bore at 6 right angle points as
shown in figure 32. Replace cylinder if bore
measures more than 2.5035 in. (63.58mm).
Fig. 32
Measure at 6 points
Top
Center
Bottom
Center Of Piston Travel

2-Cycle Snow Engine
Section 4 - Engine Overhaul
Page 14
Piston And Rings
1. Insert new rings into cylinder bore approximately
1” (25mm).
2. Use a feeler gauge to check ring end gap as
shown in figure 33. Replace ring set if gap is more
than .030 (0.76mm)
Fig. 33
3. Install new rings on piston using ring expander
(#19340).
4. Check side clearance of ring grooves as shown in
figure 34. Replace piston if clearance is more
than.005 in. (0.12mm).
Fig. 34
5. Check piston for wear or damage. Replace if
questionable.
6. Check piston pin bore (Figure 35) using dial
caliper (#19199). Replace piston if bore is more
than .501 in. (12.72mm).
7. Check piston diameter using a dial caliper
(#19199). Replace piston if diameter is less than
2.4935 in. (63.33mm).
Fig. 35
Piston Pin (Wrist Pin) And Connecting Rod
1. Check piston pin in two directions as shown in
figure 36. Replace pin if diameter is less than
.4993 in. (12.68mm).
Fig. 36
2. Visually check crank pin bearing (Figure 37) for
wear or damage. Replace connecting rod if piston
pin bearings are loose or damaged.
Fig. 37
Use New Piston Rings
Piston Pin Bearing
Crank Pin Bearing