Yamaha F15MHX Manuel D'entretien page 238

POWR
C
B
A
1
CAMSHAFT AND VALVES
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.
Valve seat cutter set:
YM-91043-C/90890-06803
Valve seat lapper:
N.A./90890-06805
9 Refer to the following chart to deter-
mine the appropriate valve seat cut-
ter.
Valve seat area
A
B
C
Valve seat cutting guidelines
1 The valve seat is centred on the valve face,
but is too wide.
Valve seat cutter set
First:
Use 90° cutter
lightly Second:
30° cutter
5-28
E
Valve cutter
90°
45°
30°
Desired result
To reduce the
valve seat width.