3. TROUBLESHOOTING
40
Valve spring retainer
：
Push down the valve spring and move the retainer to the side so that valve stems slips
through the side hole.
Do not remove the valve spring retainers while the cylinder
head is attached to the cylinder, or the valves will drop into
the crankcase.
2
）
Inspect/ Service/ Repair
：
①
Valve stem outside diameter
Inspect the valve stem outside diameter with the micrometer,
if finding out of the standard or service limit, or if visually
inspecting the burn and damaged on the valve face, please
replace with new one.
Standard Service
Limit
6.59mm
（
IN
）
6.55mm
（
EX
）
6.44mm
（
IN
）
6.40
（
EX
）
②
Valve spring free length
Measure the free length of the valve springs. If out of the
standard or service limit, please replace the spring.
Standard Service
Limit
39.0mm 37.5mm
③
Valve Guide
Inspection
：
a) Inspect the valve guide for smooth, scratch and damaged in the inner surface, and
matching between the valve guide and cylinder cover for fastness.
