Checking The Camshafts - Yamaha F90D Service Manual

POWR
5. Use a 45° cutter to adjust the contact
width of the valve seat to specification.
b
c
b Previous contact width
c Specified contact width
6. If the valve seat contact area is too wide
and situated in the center of the valve
face, use a 30° cutter to cut the top edge
of the valve seat, a 60° cutter to cut the
bottom edge to center the area and set
its width.
b Previous contact width
7. If the valve seat contact area is too nar-
row and situated near the top edge of the
valve face, use a 30° cutter to cut the top
edge of the valve seat. If necessary, use
a 45° cutter to center the area and set its
width.
b Previous contact width
5-31
Power unit
45˚
S69J5900
8. If the valve seat contact area is too nar-
row and situated near the bottom edge of
the valve face, use a 60° cutter to cut the
bottom edge of the valve seat. If neces-
sary, use a 45° cutter to center the area
and set its width.
b Previous contact width
9. Apply a thin, even layer of lapping com-
pound onto the valve seat, and then lap
the valve using a valve lapper (commer-
cially available).
CAUTION:
Do not get the lapping compound on the
valve stem and valve guide.
10. After every lapping procedure, be sure to
clean off any remaining lapping com-
pound from the cylinder head and the
valve.
11. Check the valve seat contact area of the
valve again.

Checking the camshafts

1. Measure the cam lobe. Replace if out of
specification.
6D81G11