Yamaha F15A - Valve Seat Cutting Guidelines; Valve Seat Refacing

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CAMSHAFT AND VALVES
POWR
Valve seat refacing
NOTE:
After refacing the valve seat or replacing
the valve and valve guide, lap the valve
seat and valve face.
cC
8 To prevent chatter marks, turn the
valve seat cutter clockwise with an
even, downward pressure (4 ~ 5 kg).
8 Rotate the cylinder head to maintain
an even.
9 Refer to the following chart to deter-
mine the appropriate valve seat cut-
ter.
5-28
Valve seat cutter set:
YM-91043-C/90890-06803
Valve seat lapper:
N.A./90890-06805
A
B
C
Valve seat area Valve cutter
A 90°
B 45°
C 30°
Valve seat cutting guidelines
1 The valve seat is centred on the valve face,
but is too wide.
Valve seat cutter set Desired result
First:
Use 90° cutter To reduce the
lightly Second: valve seat width.
30° cutter
1