Note: Ensure all piston rings are fitted in their original locations (if original rings are being reused) or to the piston/bore which the end gaps were checked (if new rings are being fitted).
Caution! Do not expand the piston rings any more than is necessary to allow them to be installed on the piston. The rings are brittle and will break if expanded too much.
2. Fit the oil control ring expander to the piston then install the upper and lower control rings (the oil control rings are both the same and can be fitted either way up).
Note: Ensure the second and top compression rings are correctly installed. The second and top compression rings are different and are not interchangeable.
3. Fit the second compression ring carefully to the piston, ensuring its 2T mark is facing upwards.
4. Fit the top compression ring to the piston ensuring its 1T mark is facing upwards.
Piston ring identification
5. Ensure all piston rings move freely in their grooves.
6. Fit the piston onto the connecting rod.
Note: Connecting rods may be fitted either way round. However, ensure all three are fitted the same way.
7. Lubricate the piston, small end and gudgeon pin with a 50/50 solution of engine oil and molybdenum disulphide grease.
8. Align the small end in the connecting rod with the gudgeon pin hole in the piston and fit the gudgeon pin.
9. Fit new circlips on both sides of the gudgeon pin ensuring the circlips are correctly fitted in the grooves.
Warning! Failure to use new gudgeon pin circlips could allow the pin to detach from the piston. This could seize the engine leading to loss of motorcycle control and an accident.
10. Position the piston ring end gaps as follows (piston viewed from above, triangular mark facing forwards).
Piston ring end gap locations: 1. Top ring; 2. Second ring; 3. First steel oil control ring; 4. Oil control ring expander; 5. Second steel oil control ring
Note:
- The top compression ring gap should be in the 12 o'clock position.
- The second compression ring gap should be in the 6 o'clock position.
- The first oil control ring gap should be in the 12 o'clock position.
- The second oil control ring gap should be in the 6 o'clock position.
- The oil control ring expander gap should be in the 7 o'clock position.
11. Fit the piston and connecting rods to the barrel then to the crankcase (see Barrels - installation).