Yamaha XVS650 - Page 132

VALVES AND VALVE SPRINGS
9.Lap:
• Valve face
• Valve seat
ENG
302-024
NOTE: _
After refacing the valve seat or replacing
the valve and valve guide, the valve seat
and valve face should be lapped.
**********************************
Lapping steps:
.Applya coarse lapping compound to the
valve face.
Do not let the compound enter the gap
between the valve stem and the guide.
• Apply molybdenum disulfide oil to the
valve stem.
• Install the valve
into the cylinder head.
• 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 between
your hands.
•
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.
•
Apply Mechanic's blueing dye (Dykem) to
the valve face.
• Install the valve into the cylinder head.
• Press the valve
through the valve guide
and
onto the valve seat to make a clear
pattern.
• 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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