Whip the head off (4 bolts in the top of the engine). And see if you can prise the sleeve out from the top. Just make sure you know which way round it comes out! If you can get it out like this you will be lucky, if not...

1. Remove the pullstart, very carefully as you dont want it to fly to bits!!, then remove the rear cover of the engine.
2. Take the head off (if you havent already).
3. You now need to get the cylinder liner out. If you cand get it out from the head of the engine, push it out from underneath with a bit of wooden dowel.
4. Slip the con rod from the crank pin, then the piston and con rod will fall out.
5. If you want to remove the crankshaft you have to remove the flywheel. After you have done this you can push the crankshaft out.

Check to fo while its in bits:
1. Check the fit of the piston in the liner. It should get stuck close to TDC if you try to push it through. If it will go past the top of the liner its time for a new piston/liner.
2. Check the crankshaft for signs of wear or burn marks where it goes through the bearings.
3. Check the bearings in the case. These should be totally smooth and not feel jerky or gritty.

Put it back together in the reverse order. Use plenty of normal oil when you do, as this will protect the engine when you frst fire it up.

Word of warning: Make sure you are spotlessly clean when you take the engines apart, you dont want any grit in there. Make sure you pay close attention to the orientation of the piston and liner in the crank case. (You can mark them with a permanent marker if you like)!

These engines are very simple with very few moving parts. As long as you pay attention to the direction everything comes out you will be fine. Also when you put it all back together, run it slow for a tank or so to allow it to all bed back in again.

I have my engines apart more often than a lot of people do. Never have any problems

Hope that helps,
David