Well after blowing up my Kitaco head, valves, $25 plug, and piston, then 4 months later breaking the crank; I've given up on trying to make my little XR100 go fast.  By the way, I emailed Kitaco and they said the stock flywheel is too heavy.  Well, I didn't see that in the advertisements or instructions. So I picked up a used CRF150RB for a decent price and went to work on it. I'm still not finished, but pretty close.  List of things:  Suspension 5.8 rear spring and .40 forks springs, valved form my weight and some secrete tricks to make the forks work better, Renthal CRF mini highs, BRP clamp that move the bars out, R&D power Bowl with a 48 pilot, jetting is spot on, DMC pipe, New Bridgstones, Regina Gold chain.  The Bling would be: Wheels, plastics, graphics, all hoses.  Still need to install foot pegs (already had my foot hit the rear wheel ... twice), Hotcam (stage 1), A real front brake (450 twin piston caliper and steel braided line), maybe a smaller rear sprocket or bigger front.