Honda GX690 Workshop Manual page 121

PISTON PIN BORE I.D.
Measure and record the piston pin bore I.D. of the
piston.
STANDARD: 18.002 – 18.008 mm
(0.7087 – 0.7090 in)
SERVICE LIMIT: 18.042 mm (0.7103 in)
If the measurement is more than the service limit,
replace the piston (page 14-6).
PISTON PIN O.D.
Measure and record the piston pin O.D. at three points
(both ends and middle). Take the minimum reading to
determine piston pin O.D.
STANDARD: 17.994 – 18.000 mm
(0.7084 – 0.7087 in)
SERVICE LIMIT: 17.95 mm (0.707 in)
If the measurement is less than the service limit,
replace the piston pin (page 14-3).
PISTON PIN-TO-PISTON PIN BORE
CLEARANCE
Subtract the piston pin O.D. from the piston pin bore
I.D. to obtain the piston pin-to-piston pin bore
clearance.
STANDARD: 0.002 – 0.014 mm
(0.0001 – 0.0006 in)
SERVICE LIMIT: 0.08 mm (0.003 in)
If the calculated clearance is more than the service limit,
replace the piston pin (page 14-3) and recheck the
clearance.
If the clearance is still more than the service limit with
the new piston pin, replace the piston (page 14-6).
PISTON RING SIDE CLEARANCE
Measure the clearance between each piston ring and
ring groove of the piston using feeler gauge.
STANDARD:
Top: 0.050 – 0.080 mm (0.0020 – 0.0031 in)
Second: 0.050 – 0.080 mm (0.0020 – 0.0031 in)
SERVICE LIMIT:
Top: 0.15 mm (0.06 in)
Second: 0.15 mm (0.06 in)
If any of the measurements is more than the service
limit, inspect the piston ring width. If necessary replace
the piston rings (top, second, oil) as a set (page 14-6)
and reinspect the clearance.
If any of the measurements is still more than the service
limit with the new piston rings, replace the piston (page
14-6).
If the piston ring width is normal, replace the piston
(page 14-6) and reinspect the clearance.
If necessary replace the piston rings (top, second, oil)
as a set (page 14-6) and reinspect the clearance.
CYLINDER
14-11