Yamaha FZS600'98 Service Manual page 133

VALVES AND VALVE SPRINGS
4. Lap:
4-21
a. Apply Mechanic's blueing dye (Dykem)
b onto the valve face.
b. Install the valve into the cylinder head.
c. Press the valve through the valve guide
and onto the valve seat to make a clear
pattern.
d. Measure the valve seat width. Where the
valve seat and valve face contacted one
another, the blueing will have been re-
moved.
S valve face
S valve seat
NOTE:
After replacing the cylinder head or replac-
ing the valve and valve guide, the valve seat
and valve face should be lapped.
a. Apply a coarse lapping compound a to
the valve face.
CAUTION:
Do not let the lapping compound enter
the gap between the valve stem and the
valve guide.
b. Apply molybdenum disulfide oil onto the
valve stem.
c. 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 lapping compound.
NOTE:
For the best lapping results, lightly tap the
valve seat while rotating the valve back and
forth between your hand.
e. Apply a fine lapping compound to the
valve face and repeat the above steps.
f. After every lapping procedure, be sure to
clean off all of the lapping compound from
the valve face and valve seat.
g. Apply Mechanic's blueing dye (Dykem)
b onto the valve face.
h. Install the valve into the cylinder head.
i. Press the valve through the valve guide
and onto the valve seat to make a clear
impression.
j. Measure the valve seat width a again. If
the valve seat width is out of specification,
reface and lap the valve seat.
ENG