8. CYLINDER HEAD/VALVES
8-25
MXU 500
INSPECTION
Valve /Valve guide
Inspect each valve for bending, burning,
scratches or abnormal stem wear.
If any defects are found, replace the valve
with a new one.
Check valve movement in the guide.
Measure each valve stem O.D.
Measure each valve guide I.D.
Subtract each valve stem O.D. from the
corresponding guide I.D. to obtain the stem-
to-guide clearance.
Service limits:
IN: 0.08 mm (0.0032 in)
EX: 0.1 mm (0.004 in)
Cylinder head
Check the spark plug hole and valve areas for
cracks.
Check the cylinder head for warpage with a
straight edge and feeler gauge.
Service Limit: 0.05 mm (0.002 in)
Valve spring
Measure the free length of the inner and outer
valve springs.
Service Limit:
Inner: 33.4 mm (1.336 in)
Outer: 38 mm (1.52 in)
If the stem-to-guide clearance exceeds
the service limits, replace the cylinder
head is necessary.
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