KYMCO AHG5, Service Manual

Page: 120 / 363

7. CYLINDER/ PISTON
DT X360
7-12
Measure the outside diameter of the piston at 9 mm up from the bottom of the skirt at a 90°
angle to the piston pin. Measure the piston with vernier calipers or a micrometer. Check the
piston for wear, damage, and extreme discoloration.
Subtract the diameter of the piston from the maximum front to rear diameter measurement
of the cylinder to calculate the piston-to-cylinder clearance. Replace the piston and cylinder
as needed to achieve a correct piston-to-cylinder clearance.
Item Standard (mm)
Piston-to-cylinder clearance 0.010 - 0.030
Measure the piston pin diameter with a micrometer. Measure the piston pin bore diameter
with vernier calipers or a small bore gauge. Measure at three different points for each.
Replace the parts if any of the specifications are not met.
Item Standard (mm)
Piston pin hole I.D. 18.002~18.008
Piston pin O.D. 17.994~18.000
Piston-to-piston pin clearance 0.002~0.014