Measure Side Clearance & End Gap

1. Measure the piston ring side clearance. If the measured value exceeds the service limit, insert a new ring in a ring groove to measure the side clearance. If the clearance still exceeds the service limit, replace the piston and rings together. If it is less than the service limit, replace only the piston rings.
Piston ring side clearance:
Standard value:
No. 1: 0.04-0.085 mm (0.0016-0.0031 inch)
No. 2: 0.04-0.085 mm (0.0016-0.0031 inch)
Limit:
No. 1: 0.1 mm (0.004 inch)
No. 2: 0.1 mm (0.004 inch)





2. To measure the piston ring end gap, insert a piston ring into the cylinder bore. Position the ring at right angles to the cylinder wall by gently pressing it down with a piston. Measure the gap with a feeler gauge. If the gap exceeds the service limit, replace the piston ring.
When replacing the ring without correcting the cylinder bore, check the gap with the ring positioned at the bottom of the ring travel. When replacing a ring, use a ring of the same size.
Piston ring service size and mark:
STD: None
0.25 mm (0.010 inch) O.S: 25
0.50 mm (0.020 inch) O.S: 50
0.75 mm (0.030 inch) O.S: 75
1.00 mm (0.039 inch) O.S: 100

NOTE: The mark can be found on the upper side of the ring next to the end.