Yamaha F20A, Service Manual

Page: 172 / 444

5-29
POWR
E
CAMSHAFT AND VALVES
Ç
The valve seat is too narrow and is near the
valve margin.
Valve seat cutter set Desired result
Use
First:
90˚ cutter
Second:
45˚ cutter To achieve a cen-
tered valve seat
with the proper
width.
Ç
Î
The valve seat is too narrow and is near the
bottom edge of the valve face.
Valve seat cutter set Desired result
Use
First:
30˚ cutter
Second:
45˚ cutter
To center the valve
seat and increase
its width.
Î