Yamaha F25A - Page 172

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