I'm trying to mod my older TN12 up. The piston/sleeve/Conrod are all good. The piston reaches the top of the sleeve with 1.5-2mm left before the piston stops. The rod also doesn't have any play.

From Steve Pond's article, I see that front port is smoothed out, but what about the exhaust port? Where would that be modified? What about the little groove on the crankcase, should I smooth that out a little bit? And what about the crankshaft inlet? How much material can be taken off a .12 piston safely?

I want to do this and am not worried about damage, but I'd like to do this correctly, or close, the first time.