Yamaha F150A, Service Manual

Page: 270 / 493

7-45
Cylinder head
0
1
2
3
4
5
6
7
8
9
10
A
Example:
• If the valve seat contact area is too wide
and situated in the center of the valve face,
cut the top edge of the valve seat using a
30° cutter. Cut the bottom edge using a 60°
cutter to center the area and set its width.
a. Previous contact width
• 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.
a. Previous contact width
• If the valve seat contact area is too narrow
and situated near the bottom edge of the
valve face, cut the bottom edge of the valve
seat using a 60° cutter. Set its width using a
45° cutter.
a. Previous contact width
7. After refacing the valve seat to the speci-
fied 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.
8. Recheck the valve seat contact area of
the valve. See “Checking the valve seat”
(7-43).
Checking the cylinder head and
cylinder block anode
1. Check the anodes. Clean if there is
grease, oil, or scales.
Do not apply grease, oil, or paint to the
anodes.
Assembling the cylinder head
1. Install a new valve seal “1” onto the valve
guide “2”.
a
30
60
30
a
60
a
Valve lapper “1”: 90890-04101
1
1
2