Griffbones, I think you missinterpreted my post. I respect the experience and knowledge of Eric, and very sure he always can find corners to gain some competitive advantage. What I said is that "on cylinder porting itself" there is not too much room to play on modern racing bikes contrary to enduro bikes where there is plenty of room..! Manufacturer's have all kind of equipment and they know exactly where to find the power, and that is one of their selling points. Why to underpower??? The answer is that sometimes they sacrifice some power for reliability, cost and emmisions. :yikes:
I have worked on racing bikes such as KTM's, KX's, YZ's and see that the circunsferential wall left out is barely to hold the piston ring. Then the choices are going up or down depending on where do you want the power band. Or perhaps playing with the blowdown period. With some sense on how a two-cycle engine works we suspect the final effect, but sometimes a threshold is reached and no more gains are possible. That was basically my question: what modifications are worthwhile????And here we are talking of motocross racing not mountain rides. :blah: