Yamaha XP500 Service Manual page 356

VALVES AND VALVE SPRINGS
b. Install the valve into the cylinder head.
c. Press the valve through the valve guide and
d. Measure the valve seat width.
NOTE:
Where the valve seat and valve face contacted
one another, the blueing will have been
removed.
L
4. Lap:
NOTE:
After replacing the cylinder head or replacing
the valve and valve guide, the valve seat and
valve face should be lapped.
M
a. Apply a coarse lapping compound a to the
Do not let the lapping compound enter the
gap between the valve stem and the valve
guide.
b. Apply molybdenum disulfide oil onto the
c. Install the valve into the cylinder head.
d. Turn the valve until the valve face and valve
NOTE:
For the best lapping results, lightly tap the
valve seat while rotating the valve back and
forth between your hands.
5 - 25
onto the valve seat to make a clear impres-
sion.
LLL L LLL L L LLL L L LLL
• valve face
• valve seat
MMM M MMM M M MMM M M MMM
valve face.
CAUTION:
valve stem.
seat are evenly polished, then clean off all
of the lapping compound.
ENG
L L LLL L L LLL L
M M MMM M M MMM M
LLL
MMM