Camshaft; Cam Sprocket And Cam Drive Sprocket - Yamaha XT550J Service Manual

3. Measure the outside diameter of the
rocker arm shaft. If it is less than the
specified value, replace the rocker arm.
Minimum outside diameter:
11.95 mm (0.470 in)
4. Calculate the clearance by subtracting
the rocker-arm-shaft outside diameter
from the rocker-arm inside diameter. If
this clearance is greater than 0.1 mm
(O.OO39 in) replace either or both parts as
necessary.
5. The rocker arm shaft has been harden-
ed; it should not wear excessively. If a
groove can be felt in the bearing surface
or if the shaft shows a blue discolora-
tion, the shaft should be replaced and
the lubrication system checked.
E. Camshafts, Cam Chains, and
Cam Sprockets
Camshaft
The cam lobe metal surface may have a blue
discoloration due to excessive friction. The
metal surface could also start to flake off or
become pitted.
1. If any of the above wear conditions are
readily visible, the camshaft should be
replaced.
2. Even though the cam lobe surface ap-
pears to be in satisfactory condition, the
lobes should be measured with a
micrometer. Cam lobe wear can occur
without scarring the surface. If this wear
exceeds the wear limit, valve timing and
lift are affected. Replace the camshaft if
wear exceeds the limit.
3-18
Wear Limit A
B
36.40mm
28.97mm
Intake
(1.4331 in)
(1.1405 in)
36.57mm
28.99mm
Exhaust
(1.4398 in) (1.1413 in)
Cam sprocket and cam drive sprocket
1. Check the cam sprocket and cam drive
sprocket for wear.