Honda GX270H Manual page 138

62Z7B000.book 7 ページ ２０１２年９月２７日 木曜日 午前１０時２１分
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VALVE STEM O.D.
Inspect each valve for bending or abnormal stem wear.
If necessary, replace the valve (page 13-4).
Measure and record each valve stem O.D.
STANDARD:
IN: 6.575 – 6.590 mm (0.2588 – 0.2594 in)
EX: 6.535 – 6.550 mm (0.2573 – 0.2579 in)
SERVICE LIMIT:
IN: 6.44 mm (0.254 in)
EX: 6.40 mm (0.252 in)
If the measurement is less than the service limit,
replace the valve (page 13-4).
GUIDE-TO-STEM CLEARANCE
Subtract each valve stem O.D. from the corresponding
guide I.D. to obtain the guide-to-stem clearance.
GX270H:
STANDARD:
IN: 0.010 – 0.037 mm (0.0004 – 0.0015 in)
EX: 0.050 – 0.077 mm (0.0020 – 0.0032 in)
SERVICE LIMIT:
IN: 0.11 mm (0.004 in)
EX: 0.13 mm (0.005 in)
GX390H1:
STANDARD:
IN: 0.010 – 0.040 mm (0.0004 – 0.0016 in)
EX: 0.050 – 0.080 mm (0.0020 – 0.0032 in)
SERVICE LIMIT:
IN: 0.11 mm (0.004 in)
EX: 0.13 mm (0.005 in)
If the calculated clearance is more than the service limit,
replace the following:
– Valves (page 13-4)
– Valve guide (page 13-8)
VALVE SPRING FREE LENGTH
Measure the valve spring free length.
STANDARD:
SERVICE LIMIT:
If the measured length is less than the service limit,
replace the valve spring (page 13-4).
39.0 mm (1.54 in)
37.5 mm (1.48 in)
CYLINDER HEAD/VALVES
13-7