English – 47
Faults and causes
Score marks on the piston (A)
1. Incorrect carburettor setting. Too high over-
speed.
2. Too low octane fuel.
3. Too low or incorrect oil in the fuel.
Carbon build-up (B)
1. Incorrect carburettor setting. Too low over-
speed.
2. Too much or incorrect oil in the fuel.
Piston ring breakage
1. Excessive engine speed.
2. Piston ring worn out.
3. Oversized piston ring groove.
(See gure 59)
7.23 Piston and cylinder – refitting
1
Lubricate the little end bearing with two-stroke oil
and insert it in the connecting rod (see gure 60).
2
Fit the piston with the arrow pointing towards the
exhaust port. Push the gudgeon pin in and t the
circlips. NOTE! Use new wire fuses (see gure 60).
3
Fit the intake manifold on the cylinder, with insula-
ting plate (4 screws).
4
Lubricate the piston ring and piston with two-stroke
oil.
5
Fit new cylinder base gaskets. Lower the cylinder
over the piston carefully.
6
Fit the cylinder bolts, tightening them in diagonal
pairs to a torque of 13–15 Nm.
NOTE!
It is very important that there are no leaks
in the inlet system, otherwise the engine
may seize.
Repair instructions
Fig 59
Fig 60
Fig 61
