Yamaha F30A Service Manual page 129

30˚
b Previous contact width
4. Use a 60° cutter to adjust the contact
width of the bottom edge of the valve
seat.
b Previous contact width
5. Use a 45° cutter to adjust the contact
width of the valve seat to specification.
b Previous contact width
c Specified contact width
6. Check the valve seat contact area of the
valve.
NOTE:
To check the valve seat contact area, see
"Checking the valve seat" (5-32).
67C3K11
b
S6AG5J60J
b
60˚
S6AG5J70J
b
c
45˚
S6AG5J80J
7. 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, and then use a 60° cut-
ter to cut the bottom edge to center the
area and set its width.
30˚
b
b Previous contact width
8. 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 and center the
area, and then use a 45° cutter to set its
width.
30˚
b
b Previous contact width
Cylinder head
1
2
3
60˚
S6AG5J30J
4
5
6
7
S6AG5J40J
8
9
5-34