I want to get my son a KX 100. I don't think he is tall enough for a 125, but I'd like to get him something that does better on hill climbing than his YZ80. Problem is, I'd like to bump up the low and mid-range power. How do I do that?
I am sure Eric Gorr can modify the porting for you. In addition ask him if a big bore kit is available. Often times a big bore kit mellows out the power in a really nice way.
Start by changing to a bigger rear sprocket. Try going up 2 teeth. If you still need more, the FMF fatty pipe will add to the bottom and boysen dual stage reeds help too.
I've posted a couple of time on this subject. Doa quick search. We've done a ton of mods - best bottom end changes were Carbontech Low Tension reeds (worked better than the Boyeson Dual Stage) and an SST pipe w/turbine core. There is no comparison to an 80. it's a great woods bike.