7. CYLINDER HEAD/VALVES MXU 300/250
VALVE /VALVE GUIDE INSPECTION
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 (replace if over):
IN : 0.06 mm (0.0024 in)
EX: 0.08 mm (0.0032 in)
If the stem-to-guide clearance exceeds
the service limits, replace the cylinder
head is necessary.
CYLINDER HEAD INPECTION
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: 0.05mm repair or replace
if over.
VALVE SPRING INSPECTION
Measure the free length of the inner and
outer valve springs.
Service Limit (replace if below):
Inner: 29.4 mm (1.176 in)
Outer: 39 mm (1.56 in)
7-11
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