My son has a 2001 yz125 that has just blown up. The piston broke and the cylinder is messed up. We were thinking of sleeving it and over sizing the cylinder to a 134cc. How will this affect the durability? Will it lend to more low end power? Will an FMF Fatty pipe perform the same as it would on a 125cc? We were working towards more low end. Thanks, and keep up the great work on the most awesome mag ever. Long live 2-strokes!!!!!!!
MissouriMy experience with going a little bigger on a 125 is that it enhances the mid-range the most and only a little on the bottom, typically flattening off on top more than stock unless the builder is really good with the porting and the head volume. The pipe will work just fine. But if you are looking for more bottom, try a flywheel weight. – Jimmy Lewis