Camshafts, Cam Chains, And Cam Sprockets - Yamaha XZ550RJ 1982 Service Manual

Valve installation
1. Lubricate the valve stem and the oil seal
with a high-quality molybdenum disul-fide
motor oil or molybdenum disulfide grease.
2. Insert the valve in the cylinder head, and in-
stall the spring seat.
3. Install the oil seal. Carefully fit the oil seal
over the valve stem and push it into position
on top of the valve guide.
4. Install both valve springs.
NOTE:
All valve springs must be installed with the greater
pitch upward as shown.
5. Install the collar. Be sure it is properly
seated on the valve springs.
6. Install the valve spring compressor, and
compress the springs.
7. Install the valve retainers. Be sure the re-
tainers properly engage the valve stem.
8. Carefully remove the valve spring com-
pressor.
WARNING:
Proceed slowly. If a retainer has not been prop-
erly installed, it could be ejected from the cylin-
der head.
9. Gently tap the end of the valve stem with a
plastic mallet. This will ensure that the re-
tainers are properly seated in the collar.

Camshafts, cam chains, and cam sprockets

Camshaft
The cam lobe metal surface may have a blue dis-
coloration due to excessive friction. The metal sur-
face could also start to flake off or become pitted.
a) If any of the above wear conditions are readily
visible, the camshaft should be replaced.
b) Even though the cam lobe surface appears to
be in satisfactory condition, the lobe 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.
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