Yamaha TT-R125E(R), Owner'S Service Manual

Page: 296 / 578

4 - 26
ENG
VALVES AND VALVE SPRINGS
INSPECTION
Valve
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 (0.0040 in)
2. Replace:
●
Valve guide
Replacement steps:
NOTE:
To ease guide removal, installation and to
maintain correct fit heat the cylinder head in
an over to 100 ˚C (212 ˚F).
●
Remove the valve guide using a valve
guide remover
1 .
●
Install the new valve guide using a valve
guide remover and valve guide installer.
●
After installing the valve guide, bore the
valve guide using a valve guide reamer
2
to obtain proper stem-to-guide clearance.
Valve guide remover:
YM-4097/90890-04097
Valve guide installer:
YM-4098/90890-04098
Valve guide reamer:
YM-04099/90890-04099
NOTE:
After replacing the valve guide reface the
valve seat.