If you can feel a ridge of metal or hard carbon around the top of each cylinder, remove it with a ridge reamer (A). Follow the reamer manufacturer's instructions. If the ridge is not removed, it may damage the piston as it is pushed out.
3.
Piston/Connecting Rod Assembly - Remove
1.
Use the wooden handle of a hammer (A) to drive out the piston/connecting rod assembly (B). Take care not to damage the oil jets or cylinder with the connecting rod.
2.
Reinstall the connecting rod bearings and caps after removing each piston/connecting rod assembly.
3.
Mark each piston/connecting rod assembly with its cylinder number to make sure they are reinstalled in the original order.
NOTE: The existing number on the connecting rod does not indicate its position in the engine, it indicates the rod bore size.
4.
Piston Ring End Gap - Inspect
1.
Using a ring expander (A), remove the old piston rings (B).
2.
Clean all ring grooves thoroughly with a squared-off broken ring or a ring groove cleaner with a blade to fit the piston grooves. The top groove is 1.2 mm (0.047 in) wide. The second ring groove is 1.0 mm (0.039 in) wide. The oil ring groove is 2.0 mm (0.079 in) wide. File down a blade if necessary. Do not use a wire brush to clean the ring grooves, or cut the ring grooves deeper with the cleaning tools.
NOTE: If the piston is to be separated from the connecting rod, do not install new rings yet.
3.
Using a piston that has its rings removed, push a new ring (A) into the cylinder bore 15?20 mm (0.59?0.79 in) from the bottom.
4.
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. If the bore is beyond the service limit, the engine block must be rebored.
Piston Ring End-Gap
Top Ring
Standard (New):
0.20?0.28 mm (0.008?0.011 in)
Service Limit:
0.28 mm (0.011 in)
Second Ring
Standard (New):
0.29?0.41 mm (0.012?0.016 in)
Service Limit:
0.41 mm (0.016 in)
Oil Ring
Standard (New):
0.10?0.40 mm (0.004?0.015 in)
Service Limit:
0.40 mm (0.015 in)
5.
Piston Pin - Remove
1.
Apply new engine oil to the piston pin snap rings (A), and turn them in the ring grooves until the end gaps are lined up with the cutouts in the piston pin bores (B).
NOTE: Take care not to damage the ring grooves.
2.
Remove snap rings (A) from both sides of each piston. Start at the cutout in the piston pin bore. Remove the snap rings carefully so they do not go flying or get lost. Wear eye protection.
3.
Heat the piston and connecting rod assembly to about 158 °F (70 °C).
4.
Remove the piston pin.
6.
Piston Pin - Inspect
1.
Measure the diameter of the piston pin.
Piston Pin Diameter
Standard (New):
19.960?19.964 mm (0.78583?0.78598 in)
Service Limit:
19.957 mm (0.78571 in)
2.
Zero the dial indicator to the piston pin diameter.
3.
Check the difference between the piston pin diameter and the piston pin hole diameter in the piston.
Piston Pin-to-Piston Clearance
Standard (New):
-0.004?0.004 mm (-0.00016?0.00016 in)
Service Limit:
0.007 mm (0.00028 in)
4.
Measure the piston pin-to-connecting rod clearance.
Piston Pin-to-Connecting Rod Clearance
Standard (New):
0.004?0.016 mm (0.00016?0.00063 in)
Service Limit:
0.016 mm (0.00063 in)
1.
Piston Pin - Install
1.
Install a snap ring (A) only on one side.
2.
Coat the piston pin bore in the piston, the bore in the connecting rod, and the piston pin with new engine oil.
3.
Heat the piston to about 158 °F (70 °C).
4.
Assemble the piston (A) and the connecting rod (B).
NOTE: Align the arrow (C) with the groove (D) direction on the connecting rod as shown.
5.
Install the piston pin (E).
6.
Install the remaining snap ring (F).
7.
Turn the snap rings in the ring grooves until the end gaps are positioned at the bottom of the piston.
2.
Piston Ring - Install
1.
Install the top ring and the second ring as shown. The top ring (A) has a 1R mark, and the second ring (B) has a 2R mark. The manufacturing marks (C) 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.
4.
After installing a new set of rings, measure the ring-to-groove clearances:
Top Ring Clearance
Standard (New):
0.060?0.085 mm (0.003 in)
Service Limit:
0.11 mm (0.004 in)
Second Ring Clearance
Standard (New):
0.035?0.060 mm (0.002 in)
Service Limit:
0.08 mm (0.003 in)
3.
Piston/Connecting Rod Assembly - Install
1.
Remove the connecting rod bearing caps, then install the ring compressor. Check that the bearing is securely in place.
2.
Apply new engine oil to the piston, the inside of the ring compressor, and the cylinder bore, then attach the ring compressor to the piston/connecting rod assembly.
3.
Position the mark (A) to face the cam chain side of the engine.
4.
Position the piston/connecting rod assembly in the cylinder, and tap it in using the wooden handle of a hammer (A). Push down on the ring compressor (B) to prevent the rings from expanding before entering the cylinder bore.
5.
Stop after the ring compressor pops free, and check the connecting rod-to-rod journal alignment before pushing the piston into place.
