Yamaha F75F - Checking the Rocker Arm and Rocker Arm Shaft

Camshaft and valve
7-37
• If the valve seat contact area is too
narrow and situated near the top
edge of the valve face, cut the top
edge of the valve seat using a 30
cutter to center the area. Set its
width using a 45 cutter.
• If the valve seat
contact area is too
narrow and situated near the bottom
edge of the valve face, cut the bot-
tom edge of the valve seat using a
60 cutter. Set its width using a 45
cutter.
f. After refacing the valve seat to the
specified contact width,
apply a thin,
even layer of lapping compound onto
the valve seat, and then lap the valve
using the special service tool “1”.
Do not get the lapping compound on the
valve stem and valve guide.
g. Recheck the valve seat contact area
of the valve. See “Checking the valve
seat” (7-34).
Checking the rocker arm and rocker
arm shaft
1. Check:
• Rocker arms, rocker arm shaft, and con-
tact surface “a” of each rocker arm
Worn  Replace.
2. Measure:
• Rocker arm inside diameter “b”
and rocker
arm shaft outside diameter “c”
Out of specification  Replace.
a. Previous contact width
a. Previous contact width
30°
a
60°
a
Valve lapper “1”
90890-04101
1
a
b
c