Yamaha YZ 2020 Series, Owner'S Service Manual

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TROUBLESHOOTING
9-4
EAM30510
TROUBLESHOOTING OF CLUTCH
Manual clutch
Noise heard from around piston
Worn or damaged piston ring
Replace the piston and piston
rings as a set.
Worn or damaged piston
Replace the piston and piston
rings as a set.
Worn piston (piston pin hole)
Replace the piston and piston pin
as a set.
Worn or damaged piston pin Replace the piston pin.
Worn or damaged cylinder bore
Replace the cylinder, piston, and
piston rings as a set.
Carbon buildup in piston head and
combustion chamber
Clean the piston head and com-
bustion chamber.
Noise heard from around crank-
shaft
Worn or damaged crankshaft jour-
nal or crank pin
Replace the crankshaft.
Cracked, worn, or damaged bal-
ancer shaft
Replace the balancer drive gear
and balancer shaft as a set.
Worn or damaged balancer drive
gear
Replace the balancer drive gear
and balancer shaft as a set.
Worn or damaged big end bearing Replace the big end bearing.
Worn or damaged crankshaft jour-
nal bearing
Replace the crankshaft journal
bearing.
Worn or damaged balancer shaft
journal bearing
Replace the balancer shaft journal
bearing.
Symptom Possible cause Actions
Clutch slippage
Improperly assembled clutch Reassemble the clutch.
Improperly adjusted clutch cable Adjust the clutch lever free play.
Loose clutch spring
Tighten the clutch spring bolts to
the specified torque.
Fatigued clutch spring
Replace the clutch springs as a
set.
Warped pressure plate Replace the pressure plate.
Worn friction plate
Replace the friction plates as a
set.
Warped or worn clutch plate Replace the clutch plates as a set.
Incorrect oil level
Adjust the engine oil level to the
specified level.
Incorrect oil viscosity (low)
Change to recommended engine
oil.
Deteriorated oil
Change to recommended engine
oil.
Symptom Possible cause Actions