I have 2002 CRF 450-R, and at high speeds upwards of 55 MPH, the bike starts to sputter like it is not getting fuel. I know I am not hitting the rev limiter. Any thoughts as to what is causing this. I was riding in Vegas over the weekend, so maybe the altitude had something to do with it. I only noticed it in 5th gear. I didn't run it that fast in the lower gears to see if it still sputtered. I just purchased the bike. It has a Baja-Designs Dual sport kit on it, so when I was on the highway, in between trails, is when I noticed it.