Honda SH300 2006 Manual page 229

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)
Ream the guides to remove any carbon build-up
before measuring the guide.
Insert the reamer from the combustion chamber
side of the head and always rotate the reamer clock-
wise.
TOOL:
Valve guide reamer, 4.5 mm
Measure each valve guide I.D. and record it.
SERVICE LIMIT: IN/EX: 4.54 mm (0.179 in)
Subtract each valve stem O.D. from the correspond-
ing guide I.D. to obtain the stem-to-guide clearance.
SERVICE LIMITS: IN: 0.08 mm (0.003 in)
If the stem-to-guide clearance exceeds the service
Inspect and reface
limit, determine if a new guide with standard
the valve seats
dimensions would bring the clearance within toler-
whenever the valve
ance. If so, replace any guides as necessary and
guides are replaced
ream to fit.
(page 9-15).
If the stem-to-guide clearance exceeds the service
limit with a new guide, also replace the valve.
EX: 4.455 mm (0.1754 in)
07HMH-ML00101
EX: 0.09 mm (0.004 in)
CYLINDER HEAD/VALVES
VALVE GUIDE
REAMER
VALVE GUIDE
9-13