I have a 2004 WR450 and have done the free mods and JD jetting. This has worked fine for me for the past few years and all of a sudden, it wants to idle extremely high. I can put a load on the motor by putting it in first and letting the clutch out a bit and the bike will idle down for a while and then return to a high idle. The air screw and pilot jet and jetting adjustments in general have very little effect on this situation. I switch between sea-level and 9,000+ jetting twice a year and it runs the same way both places. Otherwise, the bike runs fine, but starting is not as easy as it used to be. I've taken the carb off and cleaned it, and the hot-start lever feels functional, but seems to have no effect on the way the bike runs or starts. Thanks for any help. BTW I searched for this issue and found a couple of posts, but I have a feeling my issue is not simply a jetting issue as it used to run fine as it is now.