Piston Ring End Gap Inspection - HYOSUNG Aquila 250 Service Manual

◉ PISTON PIN DIAMETER INSPECTION
Using a micrometer, measure the piston pin outside
diameter at three position, both the ends and the center.
If any of the measurements is founds less than the ser-
vice limit, replace the pin.
Piston pin diameter
Micrometer(0~25 mm) : 09900-20201
◉ PISTON RING FREE END GAP
INSPECTION
Before installing piston rings, measure the free end gap
of each ring using vernier calipers. If the gap is less than
the service limit, replace the ring.
Piston ring free end gap
1st
2nd
Vernier calipers : 09900-20101

◉ PISTON RING END GAP INSPECTION

Insert the piston ring squarely into the cylinder using the
piston head.
Measure the end gap with a thickness gauge.
If the gap exceeds the service limit, replace the piston
ring.
Piston ring end gap(Free condition)
1st
2nd
Thickness gauge : 09900-20806
◉ PISTON RING-TO-GROOVE CLEAR-
ANCE INSPECTION
Remove carbon deposit both from the piston ring and its
groove.
Fit the piston ring into the groove. With the ring com-
pressed and lifted up, measure the clearance on the
bottom side of the ring using a thickness gauge.
Piston ring-groove clearance
1st
2nd
Service limit
14.980 mm
Standard Service limit
7.2 mm 5.7 mm
5.8 mm 4.6 mm
Standard Service limit
0.20~0.32 mm 0.5 mm
0.20~0.32 mm 0.5 mm
Service limit
0.180 mm
0.150 mm
ENGINE 3-28