Questions, again?

When they advertise a wonnser piston for a 86 mm bore (example) is it undersize or at 86mm?

I'm getting ready to sent out my 500 cr crank, cylinder, piston to have the new hva rod installed. And the crank assembly balanced, I'm going to port it by taking out the imperfections to increase the flow., add the UFO in the 40 mm carb and call it done.

Building one engine at a time. Assembling one bike at a time. Lol

I'm slow but getting all fired up.

It should be 85.94mm or something like that just like the stock Mahle pistons were.

Bigbill, this is for a 68mm bore