I have an 08 YFZ450 with hotcams and an aftermarket exhaust. I just moved to Colorado where the elevation is 6000 Ft. Much higher than Illinois. I had a guy jet my quad while i was in illinois with the dynojet jet kit and he put in the 126 main jet and the dynojet pilot needle with the e-clip on groove #3 from the top. I just dug into it to see what i needed to do for the jetting and the jet that he put in is the one dynojet suggests for elevation above 6000 ft. (the 126 main jet) I have the fual mixture screw turned out one turn. My bike idles pretty smooth but it backfires when i crank the throttle to about half. Any suggestions.