jet too big?

[400exKy1e]

i am running a 170 main jet with an open airbox, k&n and fmf powercore IV silencer. it was this way when i bought it, and i was told it gave more bottom end that way.. is this true? also, when its in nuetral it backfires when i rev it .. doesnt that mean its too lean? thanks for any help

kyle

[atvracr350]

Right now i ham running a procircuit full system, drilled airbox lid, k&n filter and only running a 158 jet. i definetly think a 170 is to rich. Backfiring when revving it up in neutral doesn't neccesarily means its lean but the only way you are really gonna find out if the jetting is good or not is to run it hard down the road then hard back and pull the plug and check the color. It should be a tanish color. Hope this helps.

Kyle

[440exnacsracer]

if you are going slightly above idle and pin it and it hesitates, this also means it is too rich, i had a 180 on my 440ex with pipe, open air box, and filter so i would say a 170 is too high

[400exKy1e]

ok thanks for the help, what jet would u suggest i use? also, it will be a dynojet so please use that size since i have heard they are different

[cals400ex]

i would put in a 42 pilot jet. it isnt good for it to rev it up in neutral. for the mainjet, i would try around a 150. i know they don't give you a 150 in the kit but i can't remember exactly what they do give you. i think you will have a 148 and 155 DJ. i would try either of these.

[400exKy1e]

ok thanks a ton for ur help, im already running a 42 pilot with no choke so ill try those.

kyle

[400exKy1e]

i put the 155 dynojet in and the backfiring is gone and throttle response sounds much more crisp and quicker. havent got to ride it yet though this was just my observations from revving it alittle in nuetral.

thanks again
kyle

[cals400ex]

the main difference should be in the last 2 or 3 gears.

[440exnacsracer]

sounds like you should have it then, just hop on and go from just above idle in first and pin it to see if it hesitates, if not, should be good to go;)