[rpduc]

Thanks for the info Glenn and Jostby. The Vertex is obviously an "A" piston so I assume the Wiseco(?) is too since it's the same dia. The cyl is stamped "A" too.

Likely you can clean things up and go with a Vertex a size or two up from your cyl. size.

So how thick is that Nikasil?? From your explanation I'd say that the scoring is minimal at worst. I can still see a trace of the old crosshatching in the worst area. (can even see it in the pic) There is a barely perceptible "step" in the cyl wall at TDC.

If I can get away with just honing and an oversize piston what's the procedure for selecting the right piston? I'm guessing my buddy Fred at Silverback Performance has a bore mic. I don't think he messes with two smokes much but he could probably mic it for me.

I checked compression before I tore it apart and it was 160... 168 after squirting in a shot of WD-40 per the instructions on RBD's website.

There was only one very thin green base gasket.

The other thing I noticed is there seems to be a LOT of end play in the shaft (?) of the powervalve. The shaft (and bearings) slide back and forth between those socket head retention screws a good 1mm or more. Is that normal?