Yamaha YFM660FS, Supplementary Service Manual

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10 - 3
TRBL
SHTG
FAULTY DRIVE TRAIN
FAULTY DRIVE TRAIN
The following conditions may indicate damaged shaft drive components:
NOTE:
Areas A, B, and C above may be extremely difficult to diagnose. The symptoms are quite subtle and
difficult to distinguish from normal machine operating noise. If there is reason to believe these com-
ponents are damaged, remove the components and inspect them.
Symptoms Possible Causes
1.A pronounced hesitation or “jerky” movement
during acceleration, deceleration, or sustained
speed. (This must not be confused with
engine surging or transmission characteris-
tics.)
2.A “rolling rumble” noticeable at low speed; a
high-pitched whine; a “clunk” from a shaft
drive component or area.
3.A locked-up condition of the shaft drive mech-
anism, no power transmitted from the engine
to the front and/or rear wheels.
A.Bearing damage.
B.Improper gear lash.
C.Gear tooth damage.
D.Broken drive shaft.
E.Broken gear teeth.
F.Seizure due to lack of lubrication.
G.Small foreign objects lodged between the
moving parts.