KYMCO Mongoose/KXR 250 Service Manual page 96

7
. CYLINDER HEAD/VALVES
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: IN : 0.06mm replace if over
EX: 0.08mm replace if over
If the stem-to-guide clearance exceeds
the service limits, replace the cylinder
head as 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:
Inner: 29.4mm replace if below
Outer: 39mm replace if below
Mongoose/KXR 250
7-10