Piston Ring: Service and Repair

END GAP





1. Using a piston, push a new ring into the cylinder bore 15 - 20 mm (0.6 - 0.8 inch) from the bottom.
2. Measure the piston ring end-gap with a feeler gauge:
- If the gap is too small, check to see if you have the proper rings for your engine.
- If the gap is too large, recheck the cylinder bore diameter against the wear limits.
If the bore is over the service limit, the cylinder block must be rebored.

Piston Ring End Gap
Top Ring
Standard (New): 0.25 - 0.35 mm (0.010 - 0.014 inch)
Service Limit: 0.60 mm (0.024 inch)
Second Ring
Standard (New): 0.60 - 0.75 mm (0.024 - 0.030 inch)
Service Limit: 0.90 mm (0.035 inch)
Oil Ring
Standard (New): 0.20 - 0.70 mm*1 (0.008 - 0.028 inch); 0.20 - 0.50 mm*2 (0.008 - 0.020 inch)
Service Limit: 0.80 mm (0.031 inch)*1; 0.60 mm (0.024 inch)*2

*1: RIKEN manufactured piston ring.
*2: TEIKOKU PISTON RING manufactured piston ring.

REPLACEMENT





1. Using a ring expander, remove the old piston rings.
2. Clean all ring grooves thoroughly.

NOTE:
- Use a squared-off broken ring or ring groove cleaner with a blade to fit the piston grooves.
- The top and 2nd ring grooves are 1.2 mm (0.05 inch) wide. The oil ring groove is 2.8 mm (0.11 inch) wide.
- File down a blade if necessary.

CAUTION: Do not use a wire brush to clean the ring grooves, or cut the ring grooves deeper with cleaning tools.

NOTE: If the piston is to be separated from the connecting rod, do not install new rings yet.

3. Install new rings in the proper sequence and position.

NOTE: Do not use old piston rings.

RING-TO-GROOVE CLEARANCE





After installing a new set of rings, measure the ring-to-groove clearances:

Top Ring Clearance:
Standard (New): 0.055 - 0.085 mm (0.0022 - 0.0033 inch)
Service Limit: 0.13 mm (0.005 inch)
Second Ring Clearance:
Standard (New): 0.040 - 0.070 mm (0.0016 - 0.0028 inch)
Service Limit: 0.13 mm (0.005 inch)

ALIGNMENT





1. Install the rings as shown.

NOTE:
- The top ring has an R1 or T1 mark.
- The second ring has an R2 or 2T mark.





Piston Ring Dimensions

Top Ring (Standard):
A: 3.1 mm (0.12 inch)
B: 1.2 mm (0.05 inch)
Second Ring(Standard):
A: 3.2 mm (0.13 inch)
B: 1.2 mm (0.05 inch)





NOTE: The manufacturing marks must be facing upward.

2. Rotate the rings in their grooves to make sure they do not bind.





3. Position the ring end gaps as shown: