Originally Posted by
performula
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.
the exhaust port? Where would that be modified: for top end you would have to cut the top edge to increment exhaust duration, but that has to be done in degrees and very tricky if you are not experienced.
And what about the crankshaft inlet? here is where you get the most notorious engine improvement. Induction timing works like this: earlier opening = more low end . Later closing = more top end.
Also keep in mind that the greatest boost in power is gained by increasing total induction duration, and increasing inner diameter of passage in crankshaft.
How much material can be taken off a .12 piston safely? stay away from this option.
AFM