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 in) 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 Gap:
Top Ring:
Standard (New): 0.20 - 0.35 mm (0.008 - 0.0014 inch)
Service Limit: 0.60 mm (0.024 inch)
Second Ring:
Standard (New): 0.40 - 0.55 mm (0.016 - 0.022 inch)
Service Limit: 0.70 mm (0.028 inch)
Oil Ring:
Standard (New): 0.20 - 0.70 mm (0.08 - 0.028 inch)
Service Limit: 0.80 mm (0.031 inch)

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

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

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

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





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

NOTE: Do not reuse old piston rings.

RING TO GROOVE CLEARANCE





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

Top Ring Clearance:
Standard (New): 0.035 - 0.060 mm (0.0014 - 0.0024 inch)
Service Limit: 0.13 mm (0.005 inch)
Second Ring Clearance:
Standard (New): 0.30 - 0.055 mm (0.0012 - 0.0022 inch)
Service Limit: 0.13 mm (0.005 inch)

ALIGNMENT





1. Install the rings as shown.

NOTE:
- The top ring has a 1B mark.
- The second ring has a 2B mark.






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

Second Ring (Standard)
A: 3.4 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: