Thanks guys,
Andy, I agree about the higher compression, it is certainly nothing I want at this point. I may ask around a bit for a few measured figures on a stock piston- then honestly lathe these off. The "hump" is not hollow, but I do see a few balancing marks, so someone had an idea what they were doing.
The more I think on it, these pistons may have been the saving grace for this bike. The brothers told me that after the (chopper) "rebuild", the bike never did run correctly, and during trying to figure out what was wrong they gave up on the project.
Of coarse, this was after they broke every other fin off the head, and drilled 5/16 holes in the rest and threw all the hard to find bits away.
I figure this is what happend: they added HC pistons to a good running motor, swapped out the smaller carburator for a larger bore/jetting, and added straight pipes. The Mag may have been a little weak so really poor spark now, coupled with flooding and no exhaust back-pressure and that was the end. Lucky me!
Lee
