Yamaha YZ125X 2023, Owner'S Manual

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TROUBLESHOOTING
7-5
Excessive noise from engine
—
Failed air induction system
Check the air induction system.
Repair or replace faulty parts.
Clogged vacuum hose Clean the vacuum hose.
Cracks and damage in vacuum
hose
Replace the vacuum hose.
Damaged carburetor joint Replace the carburetor joint.
Loose carburetor joint
Tighten the carburetor joint bolts
to the specified torque.
Clogged air filter element
Clean or replace the air filter ele-
ment.
Symptom Possible cause Actions
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.
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