Valve Seat Lapping - Yamaha V star 1100 Owner's Manual

ENGINE TOP END
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104
105
106
and then use the 45° cutter to center the contact
area.
8. If the contact area is too narrow and down away
from the valve head (Figure 105), first use the 60°
cutter and then use the 45° cutter to center the con-
tact area.
9. After the desired valve seat position and width is
obtained, use the 45° cutter and T-handle and very
lightly clean away any burrs that may have been
caused by the previous cuts; remove only enough
material as necessary.
10. Make sure the finish has a smooth and velvety
surface, it should not be shiny or highly polished.
The final seating will take place when the engine is
first run.
11. Repeat Steps 1-10 for all remaining valve seats.
12. After the valve seat has been reconditioned, lap
the seat and valve as described in this chapter.

Valve Seat Lapping

Valve lapping is a simple operation that can re-
store the valve seat without machining if the amount
of wear or distortion is not too great. Lapping is also
recommended after the valve seat has been refaced
or when a new valve and valve guide have been
installed.
1. Smear a light coat of fine grade valve lapping
compound such as Carborendum or Clover Brand
on the seating surface of the valve.
2. Apply molybdenum disulfide oil to the valve
stem and insert the valve into the cylinder head.
3. Wet the suction cup of the valve lapping tool
(Figure 106) and stick it onto the valve head.
4. Lap the valve to the valve seat (Figure 107) as
follows:
a. Lap the valve by rotating the lapping stick be-
tween your hands in both directions.
b. Every 5 to 10 seconds, stop and rotate the
valve 180° in the valve seat.
c. Continue lapping until the contact surfaces of
the valve and the valve seat in the cylinder
head are a uniform gray. Stop as soon as they
turn this color to avoid removing too much
material.
5. Thoroughly clean the cylinder head and all valve
components in solvent, followed by a wash with de-
tergent and hot water.
6. After the lapping has been completed and the
valve assemblies have been reinstalled into the cyl-
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