HYOSUNG Aquila 250 Service Manual page 65

3-27 ENGINE
◉ CAM CHAIN AND CAM CHAIN GUIDE
Check the cam chain for wear, damage and kinked or bind-
ing links. If any defects are found, replace it with a new
one.
Check the cam chain guide for wear and damage. If it is
found to be damaged, replace it with a new one.
◉ PISTON DIAMETER INSPECTION
Measure the outside diameter of piston in the direction per-
pendicular to the piston pin axis at the height from the skirt
as shown in the illustration using a micrometer.
If the measurement is found less than the service limit,
replace the piston.
Piston diameter
Piston oversize
Micrometer(50~75 mm) : 09900-20203
◉ PISTON-TO-CYLINDER CLEARANCE
To determine the piston-to-cylinder clearance, calculate
the difference between the cylinder bore and outside
diameter of the piston.
Standard
Piston-to-cylin-
der clearance
0.05~0.06 mm
◉ PISTON PIN HOLE BORE
Using a dial calipers, measure the piston pin hole bore
both in the vertical and horizontal directions.
If the measurement exceeds the service limit, replace
the piston.
Piston pin hole bore
Dial calipers : 09900-20605
Service limit
56.880 mm
0.5, 1.0 mm
Service limit
0.120 mm
Service limit
15.030 mm