Yamaha VMX12H Supplementary Service Manual page 148

/ - -
INSPECTION AND REPAIR
seat is too narrow and is located down
near the bottom edge of the valve face
(see diagram "d").
Valve Seat Cutter Set
45° cutter
Valve/Valve Seat Assembly Lapping
1.
Apply:
Coarse lapping compound (small amount)
To valve face.
To valve stem.
2.
Position:
I n cylinder head.
3.
Rotate:
Turn until valve and valve seat are evenly
polished, then clean off all compound.
4. Apply:
lapping compound (small amount)
To valve face.
5. Repeat steps
NOTE:
Be sure t o clean off all compound from valve
face after every lapping operation.
6. Inspect:
face
Not yet uniformly smooth
dure from step 1.
7.
Apply:
Mechanics bluing dye
To valve face and seat.
8.
Rotate:
9.
Inspect:
face
Valve must make full seat contact indicated
by grey surface all around. The valve face
where bluing was removed.
Faulty contact
(See procedure below)
Desired Result
to increase its width
disulfide oil
3.
2 and
Repeat proce-
Dykem
Replace.
3-24