Bought a stihl saw at the weekend, took a chance on a non runner that had a spark and seemed to have compression (but doesnt). Ive stripped it down now to find the top ring has half an inch mising and the bottom ones a bit worn. New rings are only a fiver, but the pin that stops the rings rotating has worn away, so does this mean i need a new piston too or how can i extract the remains of the pins to replace them? Also the very top of the bore has a bit of a lip in one place, are these engines pretty forgiving for wear or will it not have any chance of running again? Dont particularly want to buy a new barrel and piston kit at £40 as i only bought the saw cause it was cheap and similarly dont want to spend another £20 on a piston kit if the bores shot as i could get my money back selling it on for spares.
Ideally id like to repair the piston to fit new rings and give it a try and see if anything else needs replacing, is this possible? I cant find a barrel on its own for sale without the full kit.
Thanks

[Edited on 29/4/11 by andrew-theasby]

Is it the gudgen pin thats worn or the actual piston. Thats what you need to know. Theres normally a circlip at each end of the pin to hold it in.

No there is a little pin in the ring land to stop the ring turning and the ends coming into the ports.

New piston and rings if its not damaged the bore.

Used to do loads of these when I was in the block paving game. It was rarely worth replacing just the piston because it only lasted a couple of days. just go for the barrel and piston kit - it will be like new then.

If there is a lip at the top of the bore then the top ring will probably get broken again very quickly.

Ok thanks for the warning, PS it wasnt the gudgeon pin its the little pegs that hold the rings in place. Might sell it on for spares then.