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 limit, the cylinder block must be rebored.

Piston Ring End-Gap:
Top Ring
M/T:
Standard (New): 0.20 - 0.30 mm (0.008 - 0.012 inch)
Service Limit: 0.50 mm (0.020 inch)
A/T:
Standard (New): 0.25 - 0.40 mm (0.010 - 0.016 inch)
Service Limit: 0.60 mm (0.024 inch)
Second Ring
Standard (New): 0.35 - 0.50 mm (0.014 - 0.020 inch)
Service Limit: 0.75 mm (0.03 inch)
Oil Ring
Standard (New): 0.20 - 0.70 mm (0.008 - 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 ring grooves thoroughly.

NOTE:
- Use a squared-off broken ring or ring groove cleaner with blade to fit piston grooves.
- Top and 2nd ring grooves are 1.2 mm (0.05 inch) wide and the oil ring groove is M/T: 2.5 mm (0.10 inch), A/T: 2.8 mm (0.11 inch) wide.
- File down the blade if necessary.

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






3. Install 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 ring-to-groove clearances:





Top Ring Clearance
M/T:
Standard (New): 0.035 - 0.065 mm (0.0014 - 0.0026 inch)
Service Limit: 0.13 mm (0.005 inch)
A/T:
Standard (New): 0.030 - 0.055 mm (0.0012 - 0.0022 inch)
Service Limit: 0.13 mm (0.005 inch)
Second Ring Clearance
M/T:
Standard (New): 0.030 - 0.060 mm (0.0012 - 0.0024 inch)
Service Limit: 0.13 mm t0.005 inch)
A/T:
Standard (New): 0.030 - 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 an R1 or R mark.
- The second ring has an R2 or RN mark.





Piston Ring Dimensions:
Top Ring (Standard):
A:
*1: 3.6 mm (0.14 inch)
*2: 3.3 mm (0.13 inch)
B: 1.2 mm (0.05 inch)

Second Ring (Standard):
A:
*1: 3.75 mm (0.148 inch)
*2: 3.8 mm (0.15 inch)
B: 1.2 mm (0.05 inch)

*1: M/T
*2: A/T





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: