Yamaha XVS6501997 Service Manual page 129

VALVES AND VALVE SPRINGS
9. Lap:
S Valve face
S Valve seat
NOTE:
After refacing the valve seat or replacing the
valve and valve guide, the valve seat and valve
face should be lapped.
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Lapping steps:
D Apply a coarse lapping compound to the
valve face.
CAUTION:
Do not let the compound enter the gap be-
tween the valve stem and the guide.
D Apply molybdenum disulfide oil to the valve
stem.
D Install the valve into the cylinder head.
D Turn the valve until the valve face and valve
seat are evenly polished, then clean off all of
the compound.
NOTE:
For best lapping results, lightly tap the valve
seat while rotating the valve back and forth be-
tween your hands.
D Apply a fine lapping compound to the valve
face and repeat the above steps.
NOTE:
After every lapping operation be sure to clean
off all of the compound from the valve face and
valve seat.
D Apply Mechanic's blueing dye (Dykem) to the
valve face.
D Install the valve into the cylinder head.
D Press the valve through the valve guide and
onto the valve seat to make a clear pattern.
D Measure the valve seat width again. If the
valve seat width is out of specification, reface
and relap the valve seat.
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4-25
ENG