Yamaha BEARTRACKER YFM250XC, Service Manual

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ENG
INSPECTION AND REPAIR
3.Measure:
●
Valve stem runout
Out of specification
→
Replace.
Stem runout:
Less than: 0.03 mm (0.0012 in)
4.Measure:
●
Valve stem clearance
Out of specification
→
Replace either
valve and/or guide.
Use a Micrometer and Bore Gauge
1 .
VALVE GUIDE
NOTE:
●
Always replace the valve guide if the
valve is replaced.
●
Always replace the oil seal if the valve is
removed.
1.Inspect:
●
Valve guide
Wear/Oil leakage into cylinder
→
Replace.
2.Remove:
●
Valve guide
Use the Valve Guide Remover
1 .
NOTE:
Heat the head in an oven to 100C (212F) to
ease guide removal and installation and to
maintain correct interference fit.
Valve stem clearance =
Valve guide inside diameter
Å
–
Valve stem diameter
ı
Valve stem clearance Limit
Intake
0.010 ~ 0.037 mm
(0.0004 ~ 0.0015 in)
0.08 mm
(0.0031 in)
Exhaust
0.025 ~ 0.052 mm
(0.0010 ~ 0.0020 in)
0.10 mm
(0.0039 in)
Valve guide remover (6.0 mm):
P/N. YM-04064-A, 90890-04064
4