Yamaha TTR90(M), Owner'S Service Manual

Page: 180 / 287

4 - 17
ENG
VALVES AND VALVE SPRINGS
REMOVAL POINTS
Valve removal
1. Remove:
●
Valve cotters 1
NOTE:
Attach a valve spring compressor 2 between
the valve spring retainer and the cylinder head
to remove the valve cotters.
Valve spring compressor:
YM-01253/90890-01253
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 (0.003 in)
Exhaust:
0.025 ~ 0.052 mm
(0.0010 ~ 0.0020 in)
<Limit>: 0.10 mm (0.004 in)
2. Measure:
●
Runout (valve stem)
Out of specification
→
Replace.
Runout limit:
0.02 mm (0.0008 in)