Kymco XCITING 500 - Service Manual > Service information

Cylinder/Piston / Service information







Unit: mm (in)


Compression too low or uneven compression

Compression too high

Excessive smoke from exhaust muffler

Abnormal noisy piston


Remove the cylinder head.

Take the block pin out.

Remove the water hose from the cylinder.

Remove the two cylinder bolts.

Remove the cylinder and gasket.


Remove the dowel pins


Remove the piston pin clip.

Place a clean shop towel in the crankcase to keep the piston pin clip from falling into the crankcase.

Press the piston pin out of the piston and remove the piston.


Spread each piston ring and remove it by lifting up at a point opposite the gap

Do not damage the piston ring by spreading the ends too far.

Clean carbon deposits from the piston ring grooves.



Piston ring

Inspect the piston rings for movement by rotating the rings. The rings should be able to move in their grooves without catching.

Push the ring until the outer surface of the piston ring is nearly flush with the piston and measure the ring-to-groove clearance.

Service Limits:
  Top: 0.08 mm (0.003 in)
  2nd: 0.065 mm (0.0026 in)


Insert each piston ring into the bottom of the cylinder squarely.

Use the piston head to push each piston ring into the cylinder.

Measure the piston ring end gap.

Service Limit:
  Top: 0.5 mm (0.02 in)
  2nd: 0.65 mm (0.026 in)
  Oil ring: 1 mm (0.04 in)


Piston/Piston pin

Measure the piston O.D. at the point 10 mm from the bottom and 90Вє to the piston pin hole.

Service Limit: 91.9 mm (3.676 in)

Calculate the cylinder-to-piston clearance (cylinder I.D.)


Measure the piston pin hole. Take the maximum reading to determine the I.D..

Service Limit: 22.04 mm (0.8826 in)


Measure the piston pin O.D. at piston and connecting rod sliding areas.

Service Limit: 21.96 mm (0.8784 in)

Measure the piston-to-piston pin clearance.

Service Limit: 0.002 mm (0.0001 in)



Check the cylinder for warpage with a straight edge and feeler gauge in the directions shown.

Service Limit: 0.05 mm (0.002 in)


Check the cylinder wall for wear or damage.

Measure and record the cylinder I.D. at three levels in an X and Y axis. Take the maximum reading to determine the cylinder wear.

Service Limit: 92.1 mm (3.684 in)

Calculate the piston-to-cylinder clearance.

Take a maximum reading to determine the clearance.

Service Limit: 0.1 mm (0.004 in)

Calculate the taper and out-of-round at three levels in an X and Y axis. Take the maximum reading to determine them.

Service Limit:
  Taper: 0.1 mm (0.004 in)
  Out-of-round: 0. 1 mm (0.004 in)


Measure the connecting rod small end I.D..

Service Limit: 22.06 mm (0.8824 in)

Calculate the connecting rod-to-piston pin clearance.

Service Limit: 0.06 mm (0.002 in)


See also:

 Kymco XCITING 500 - Service Manual > Cylinder/Piston

 Kymco XCITING 500 - Service Manual > Cylinder/piston installation

PISTON RING INSTALLATION Carefully install the piston rings into the piston ring grooves with the markings facing up. Be careful not to damage the piston and rings. Do not confuse the top and second rings. To install the oil ring, install the oil ring, then install the side rails.