Just put on a FMF Megamax2 silencer and K&N power kit(follow instructions to a tee for running at sea level)(170 main jet)(3.5 turns on fuel mixture screw)(notch 3 on needle) with no lid. It seems that it will cut out if you blurp the gas. But if you do a gradual acceration, everything is fine. Any ideas on what is causing this? And any fixes?

Scott
2000 400EX

 

Try a #40 pilot jet. It sounds like a 170 main jet is way to big. I am only running a 152 main on a stock engine with a Curtis Sparks Pipe and muffler.

 

You might eliminate the hesitation by tweaking the air screw if the hiccup isn't too pronounced. Other wise follow the other ride's suggestion.

 

Read the tech connection on this site. It will tell you exactly how to properly jet an engine. Do one jet curcuit at a time, starting at the main jet, then needle, then pilot. Only your engine can tell you what it wants. Wanna guess from me? When I was jetting in my 400ex (tech connection instructions) it would often do that when the main jet was too big.

ogre