Pistons - Assembly

  1. Clean the piston ring grooves and fit the piston rings to the piston.
    2. note
    The top ring upper surface is marked N and can be identified by a chamfer on the inside edge.The second ring upper surface is marked N2, and is plain on the inside edge.When new, the oil control rings can be fitted with either face upward. Used oil control rings must be refitted in the same orientation as noted prior to removal.
    Piston Rings

    Piston Ring Identification

  2. Fit the piston onto the connecting rod.
    3. note
    Connecting rods may be fitted either way around. However, ensure all three are fitted the same way.
  3. Lubricate the piston, small end and gudgeon pin with a 50/50 solution of engine oil and molybdenum disulphide grease.
  4. Align the small end in the connecting rod with the gudgeon pin hole in the piston and fit the gudgeon pin.
  5. Fit new circlips on both sides of the gudgeon pin ensuring the circlips are correctly fitted in the grooves.
    6. warning
    Failure to use new gudgeon pin circlips could allow the pin to detach from the piston. This could seize the engine, resulting in loss of motorcycle control and an accident.
  6. The piston ring gaps must be arranged as shown in the diagram below.
    7. Piston Ring Assembly

    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 ring gap should be positioned in the 12 o'clock position, and the second ring gap in the 6 o'clock position. The first steel oil control ring gap should be in the 12 o'clock position and the second steel oil control ring should be in the 6 o'clock position. The oil control ring expander should be in the 7 o'clock position.
  7. Fit the piston into the liner from below using a gentle rocking motion to engage the rings in the bore.