need help!!!

[steffen_ex]

ok i live in northeast iowa and i think my jetting on my 03' 400ex is messed up, i have dynojet jet kit and im not quite sure what jet i should use, i think that i should be running a 150 or a 155 but im not sure, im not sure what my elevation is but when im driving it it wants to sputter a little bit when i first get on the gas and it wants to backfire quite a bit also, i have a fmf powercore4 and a k&n with lid off, could someone help me figure out what the problem is?

[honda729]

I think when it backfires that means its too lean but im not 100% sure about that

[steffen_ex]

right now im runnin with a 170 and i kno that it is probably to big but do u think that it will help that much if i put in a smaller one or should i mess with the fuel air mixture? {i never touched the fuel/air screw since ive had it}

[hondaking52]

go by wat the dyno jet instrutions say, and you should be under 1000 feet,

[honda729]

is it doing it all the time or just at a certain throtle position because your main could be good and the pilot too small, i think stock screw setting is 2-2 1/2 turns out so that could be way outta wack if someone has been messin with it, so you might what to try that before you spend any money

[steffen_ex]

do u think i should try putting a smaller jet in and messin with the fuel air screw? i dont know if it is stock settings, it could be stock because i bought it completely stock and put everything on myself

[hondaking52]

put the 146 i think, DJ needle on 2nd clip down, fuel screw 3.5 turns out

[steffen_ex]

it is doing it only at low end when i first take of like when im in second gear and i want to pull a wheelie, it wants to sputter and run a little rough and then pull out of it

[steffen_ex]

should i screw it all the way in and then out 3.5 turns or the way it sits because i dont know if it is at stock setting or not

[hondaking52]

ya turn it all of the way in till it seats, you'll know wen, then turn it out 3.5 turns

[honda729]

bein that its on the lower end i would say that you pilot jet is too small if its stock then its a 38 i would think about goin to a 40 or a 42 (check fmfs website they might have jetting tips for thier pipes) Im not an expert so hopefully someone else on here will give u a second opinion before u hafta do it but that would be my guess.

[steffen_ex]

ok thanks guys ill see what i can do