Honda NSS250S Manual page 308

CYLINDER HEAD/VALVES
Check the cylinder head for warpage with a straight
edge and feeler gauge.
SERVICE LIMIT: 0.05 mm (0.002 in)
VALVE SPRING
Check the valve springs for fatigue or damage.
Measure the valve spring free length.
SERVICE LIMIT: IN/EX: 35.6 mm (1.40 in)
VALVE/VALVE GUIDE
Check that the valve moves smoothly in the guide.
Check the valves for bending, burning or abnormal
wear.
Measure each valve stem O.D. and record it.
SERVICE LIMITS:
IN: 4.465 mm (0.1758 in)
EX: 4.455 mm (0.1754 in)
Ream the valve guide to remove any carbon build
Use cutting oil on
up before measuring the guide.
the reamer during
Insert the reamer from the combustion chamber
this operation. Take
side of the head and always rotate the reamer clock-
care not to tilt or
wise.
lean the reamer in
the guide while
TOOL:
reaming.
Valve guide reamer, 4.5 mm
9-14
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07HMH-ML00101