Yamaha XVZ13TF 1999 Service Manual page 378

SHAFT DRIVE
Inspection notes
1. Investigate any unusual noises.
The following noises may indicate a me-
chanical defect:
a. A rolling "rumble" during coasting, accelera-
tion, or deceleration. The noise increases
with rear wheel speed, but does not increase
with higher engine or transmission speeds.
Diagnosis: Possible wheel bearing damage
b. A whining noise that varies with acceleration
and deceleration.
Diagnosis: Possible incorrect reassembly,
too little gear lash
CAUTION:
Insufficient gear lash is extremely destruc-
tive to the gear teeth. If a test ride following
reassembly indicates this condition, stop
riding immediately to minimize gear dam-
age.
c. A slight "clunk" evident at low speed opera-
tion. This noise must be distinguished from
normal motorcycle operation.
Diagnosis: Possible broken gear teeth
WARNING
Stop riding immediately if broken gear teeth
are suspected. This condition could result
in a locking of the shaft drive assembly,
causing loss of control of the motorcycle
and possible injury to the rider.
2. Check:
S drained oil
Drained oil contains a large amount of metal
particles ! Check the bearing for seizure.
NOTE:
A small amount of metal particles in the oil is
normal.
7-75
CHAS