so apart from another burnt out valve it looks like ive cattle-trucked a piston (different clyinder too)! i did wonder why i had oil coming out the air intake.
gives me an excuse to get a 1242.

Ah the 50p piston crown. Nope it is supposed to be round, as you well know. It will probably have done the rings too and left a nasty score on the bore.

New engine time.

Cheers

D