I just did the cam mod on my 05' yfz450, now it runs great. ONCE IT IS RUNNING. But it is extememly difficult to get started and doesn't idle very well. Do I have to re-jet the pilot jet or something to fix this? If so what is a suggested start. I am running stock right now and have a k&n filter with a fmf Q pipe.

 

Just do the pilot screw adjustment test. Determine position of pilot screw where hot idle is at maximum. If between about 1/2 and 2 turns out your pilot jet is good. If peak idle is at less than 1/2 turn out then try one size smaller pilot. If peak idle is over 2 turns out then try one size larger pilot. If you cannot determine any position where idle peaks then pilot jet needs to be changed. Usually you will need to go larger but could need smaller depending on your mods. After confirming you have correct pilot jet then set adjust screw about 1/4 turn richer (farther out) and reset idle. This is much more accurate than guessing based on what anyone else with similar mods might be running.