Lubrication system
Oil does not return to oil tank
1.oil tank empty.
2. Oil feed pump not functioning.
3. Scavenger pump gear key sheared.
4. Restricted oil filter.
5. Restricted oil lines or fittings.
Engine uses too much oil or smokes excessively
1. Valve guides or valve guide seals worn.
2. Piston rings badly worn or broken.
3. Breather valve incorrectly timed.
Engine leaks oil from cases, push rods, hoses, etc.
1. Loose part.
2. Imperfect seal at gaskets, push rod cover, washers, etc.
3. Restricted oil return line to tank.
4. Restricted breather hose to air cleaner.
Excess oil oil out of crankcase breather (air cleaner)
1. Oil not returning to oil tank.
2. Restricted oil return line to tank.
3. Restricted oil filter.
4. Oil lines or passages restricted.
5. Gearcase cover gasket not sealing.
6. Leakage between passages and pockets ingearcase cover and gearcase.
Excess oil out of crankcase breather when starting engine
1. Oil pump check ball stuck open.
2. Poor seal between feed and return gears in pump.
Electrical system
Alternator does not charge
1. Damaged rectifier-regulator module.
2. Module not grounded.
3. Loose or broken wires in charging circuit.
4. Damaged stator coil.
5. Damaged rotor.
Alternator charge rate is below normal normal
1. Loose or corroded connections.
2. Weak or damaged battery.
Damaged rectifier/regulator module.
4. Damaged stator coils.
Caburetor
Floods
1. Intel valve sticking.
2. Intel valve and/or valve seat worn or damaged.
3. Dirt or other foreign matter between valve and its seat.
4. Excessive "pumping" of hand throttle grip.
5. Leaky or damaged float.
6. Float misadjusted. See carburetor troubleshooting, section 4.
Transmission
Shifts hard
1. Bent shifter rod improperly adjusted.
2. Clutch dragging slightly.
3. Transmission lubricant too heavy (winter operation).
4. Shifter forks (inside transmission) sprung.
5. Corners worn off shifter clutch dogs (inside transmission) badly worn and rounded.
Clutch
Slips
1. Clutch controls improperly adjusted.
2. Insufficient clutch spring tension.
3. Worn friction discs.
Drags of does not release
1. Clutch controls improperly adjusted.
2. Clutch spring tension too tight.
3. Clutch discs warped.
Chatters
1. Friction discs or steel discs worn or warped.