I have had my CRF450X a few years now. I uncorked it and rejetted using the JD jet kit when it was new. The jetting has always been spot on with no flame outs and no bogging. This weekend, while riding some of the really tight trails that I normally ride, I was having flame-out problems. Every once in a while, rolling off the throttle in first gear, it would die. Any thoughts as to what may be causing this?