Alanth

Thanks, I happen to have both, but I won't use them at the same time

What's the best way of removing aluminium from the bore without damaging it?

The cylinder appears to have a liner and looked fairly OK. I could take it apart again and polish it up.

I have been given a 252RX brushcutter which has probably been run without oil. The piston is scored on the exhaust side. I have replaced the piston ring (same as on a Husky 51 chainsaw) but the compression is only about 65psi and it doesn't start. On a similar working machine its about 125psi. I was hoping the new ring would hold the pressure up, isn't that what its for? It may not be worth spending £80 ish on a new piston assembly. Is there a typical minimum pressure for an engine to function? Thanks for any ideas.