Yamaha F225F, Service Manual

Page: 343 / 576

7-60
Cylinder head
0
1
2
3
4
5
6
7
8
9
10
A
b
Previous contact width
c
Specified contact width
6. Check the valve seat contact area of the
valve. See “Checking the valve seat” (7-
58).
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, and then cut the bottom edge
using a 60° cutter to center the area and set
its width.
b
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, and
then set its width using a 45° cutter.
b
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 to center the area,
and then set its width using a 45° cutter.
b
Previous contact width
7. 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
a
. NOTICE: 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”
(7-58).
Checking the cylinder head anode
1. Check the anodes. Replace if eroded.
Clean if there is grease, oil, or scales.
NOTICE: Do not apply grease, oil, or
paint to the anodes.
Assembling the cylinder head
1. Install a new valve seal
a
. NOTICE: Do
not reuse a valve seal, always replace
it with a new one.
45˚
b
c
30˚
60˚
b
30˚
b
Valve lapper
a
: 90890-04101
60˚
b
a