I have a 2008 yfz 450, I bought it from the dealer with 20 hours on it in 2009. When I got it I had a hmf silencer put on it and they had a hard time getting it jetted right. There is no air box lid on the atv and when we go riding, if i gas on it to wheelie over a log it will stall out and die, it also turns the pipe red hot if I am cruising down a dirt road not at full throttle but 1/4 to 1/2 throttle? anybody have any suggestions? Thanks I would really like your input.