Jetting

[tide2085]

I need help with what jet to go with on my 400ex.. I have a stage 2 hotcam in it and a slip on motoworks exhaust and a k&N air filter. It backfires a lot so im guessing its getting to much air and not enough fuel so i need a bigger jet?? right?? but how much bigger.. it has stock jetting in it right now so i would appreciate any help..

[JOHNDOE83]

Theres a plug reading and jetting thread right bellow this one?

Its hard for people to guess what jett you need, some people would say a 190main is to big for a 440 big bore, but theres some 416 guys running 205 main jets..... from what youve said you need to bump up your pilot jet, a bigger main jet is also needed, you cant just go buy 1 jet and be done with it.

Read the plug reading for jetting info thread.

Just from making a guess, you need a 40 or 42 pilot, and probally a 160 main jet.....the 42 will be fine...the main jet and needle setting is gonna be some trial and error, I would buy jet sizes from 155 to 180, in incriments of 5.

[honda400ex2003]

my vote would be for something in the 155-160 range as John said. what is in it how? steve

[honda400ex2003]

also how high are you and such? if you are up over 3000 ft then a 155 should be about it i would say maybe even a 152, the cams really dont do a whole lot to change jetting from what i have seen and verified i suppose. I switch back and forth between cams and dont have to change anything. steve