Yamaha YFM660FS, Supplementary Service Manual

Page: 239 / 478

4 - 26
ENG
VALVES AND VALVE SPRINGS
CHECKING THE VALVE AND VALVE
SPRING
1.Measure:
●
Stem-to-guide clearance
Out of specification
→
Replace the valve
guide.
Stem-to-guide clearance =
valve guide inside diameter
a
–
valve stem diameter
b
Clearance (stem to guide):
Intake:
0.010 ~ 0.037 mm
(0.0004 ~ 0.0015 in)
<Limit>: 0.08 mm (0.0031 in)
Exhaust:
0.025 ~ 0.052 mm
(0.0010 ~ 0.0020 in)
<Limit>: 0.10 mm (0.0039 in)
2.Replace:
●
Valve guide
*****************************************************
Replacement steps:
NOTE:
To ease guide removal, installation and to
maintain correct fit, heat the cylinder head to
100 °C (212 °F) in an oven.
●
Remove the valve guide using a valve guide
remover
1
.
●
Install the new valve guide using a valve
guide remover
1
and valve guide installer
2
.
●
After installing the valve guide, bore the
valve guide using a valve guide reamer
3
to
obtain proper stem-to-guide clearance.
NOTE:
After replacing the valve guide reface the valve
seat.
*****************************************************
Valve guide remover (ø 6):
P/N. YM-4064-A, 90890-04064
Valve guide installer (ø 6):
P/N. YM-04065-A, 90890-04065
Valve guide reamer (ø 6):
P/N. YM-04066, 90890-04066