Yamaha 2004 YXR660 Service Manual page 249

TROUBLESHOOTING
CAUTION:
Too little gear lash is extremely destructive
to the gear teeth. If a test ride following
reassembly indicates this condition, stop
riding immediately to minimize gear dam-
age.
c. A slight "thunk" evident at low speed opera-
tion. This noise must be distinguished from
normal vehicle operation.
Diagnosis: Possible broken gear teeth.
WARNING
Stop riding immediately if broken gear
teeth are suspected. This condition could
result in the shaft drive assembly locking
up, causing loss of control of the vehicle
and possible injury to the rider.
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2. Check:
• drained oil
Drained oil shows large amounts of metal
particles → Check the bearing for seizure.
NOTE:
A small amount of metal particles in the oil is
normal.
3. Check:
• oil leakage
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a. Clean the entire vehicle thoroughly, then dry
it.
b. Apply a leak-localizing compound or dry
powder spray to the shaft drive.
c. Road test the vehicle for the distance nec-
essary to locate the leak.
Leakage → Check the component housing,
gasket, and/or seal for damage.
Damage → Replace the component.
NOTE:
• An apparent oil leak on a new or nearly new
vehicle may be the result of a rust-preventa-
tive coating or excessive seal lubrication.
• Always clean the vehicle and recheck the
suspected location of an apparent leakage.
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DRIV
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