Piston Ring Replacement

Remove the piston from the engine block (see CRANKSHAFT AND PISTON REMOVAL ).
Using a ring expander (A), remove the old piston rings (B).

Fig 1: Removing Piston Rings Using Ring Expander
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Clean all the ring grooves thoroughly with a squared-off broken ring, or a ring groove cleaner with a blade to fit the piston grooves. File down the blade, if necessary. The top and second ring grooves are 1.0 mm (0.039 in) wide, and the oil ring groove is 2.0 mm (0.079 in) wide. Do not use a wire brush to clean the ring grooves, or cut the 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.
Using a piston, push a new ring (A) into the cylinder bore 15-20 mm (0.59-0.78 in) from the bottom.

Fig 2: Identifying Piston Ring Installing Dimensions
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Measure the piston ring end-gap (B) 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 (see STRAIGHTNESS ).
If the bore is over the service limit, the engine block must be rebored.

Piston Ring End-Gap

Top Ring:

Standard (New): 0.15-0.30 mm (0.0059-0.0118 in)

Service Limit: 0.60 mm (0.0236 in)

Second Ring:

RIKEN

Standard (New): 0.30-0.42 mm (0.0118-0.0165 in)

Service Limit: 0.65 mm (0.0256 in)

NIPPON

Standard (New): 0.35-0.50 mm (0.0138-0.0197 in)

Service Limit: 0.65 mm (0.0256 in)

Oil Ring:

Standard (New): 0.20-0.70 mm (0.0079-0.0276 in)

Service Limit: 0.80 mm (0.0315 in)
Install the rings as shown. The top ring (A) has a R or 1N mark, and the second ring (B) has a 2R or 2N mark. The manufacturing marks (C) must be facing upward.

Fig 3: Identifying Piston Rings Positions
Courtesy of AMERICAN HONDA MOTOR CO., INC.
After installing a new set of rings, measure the ring-to-groove clearances:
Top Ring Clearance

RIKEN

Standard (New): 0.065-0.090 mm (0.00256-0.00354 in)

Service Limit: 0.15 mm (0.0059 in)

NIPPON

Standard (New): 0.061-0.090 mm (0.00240-0.00354 in)

Service Limit: 0.15 mm (0.0059 in)

Second Ring Clearance

Standard (New): 0.030-0.055 mm (0.00118-0.00217 in)

Service Limit: 0.12 mm (0.0047 in)

Fig 4: Measuring Piston Ring Groove Clearance
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Rotate the rings in their grooves to make sure they do not bind.
Position the ring end gaps as shown:

Fig 5: Ring End Gaps Positioning Diagram
Courtesy of AMERICAN HONDA MOTOR CO., INC.