cutting out at 1/2 - WOT

[400exKy1e]

recently i have cut out my spark arrester on my FMF powercoreIV silcencer and changed from a unifilter to a K&N. not sure if it matters but half of my airbox is cut out. i took it to the track today and when u get to about 1/2 throttle or more the engine starts cutting out, does this mean i have to rejet? thanks ahead for any help!

[quadmxracer]

you may possibly want to try a bigger main jet. What r u running now?

[400exKy1e]

i think the guy that i bought it from said it was a 180

[quadmxracer]

Take it out and see what it truly is. And let me know. You can also call me if need to (712-621-3964) name is Clayton, as I will be in my shop workin' on my quad for my race tomorrow.

[400exKy1e]

wow thanks i really appreciate that!

[cals400ex]

if it is a 180, your just too big. i would try around a keihin 158 or so.

[400exKy1e]

ok i opened it up and its a 170, and thats what the dynojet kit said i should have in there.. is it possible my needle was mest up or somethin? im gona replace that too but the soft screws in the carb are such a pain in the *****

[cals400ex]

i would say 170 is still too big. it is also possible that the mainjet just fell out or the 2 screws holding the needle down came out. where is the clip position at on the needle? i assume your choke is not on the "on" position?

[400exKy1e]

i still gotta put the new needle in im not sure what the old one was on, but i think that was the problem, and no the choke wasnt on hehe, do u know how far u are supposed to screw the thing that u screw the main jet into? cus it has the little nut so u could adjust it i guess

[cals400ex]

yes, where the mainjet screws into (needle jet holder) needs to be adjusted properly. you need to take the carb off the bike and take the bowl off. you screw the needle jet holder in and tighten the lock nut so that you can see 2-3 threads left on the needle jet holder. i hope that makes sense

i assume you have the adaptor in for the dynojets? the dynojets use an adaptor that goes into this needle jet holder because the dynojets are shorter than the stock jets. also, if your using the dynojets, i would use their needle too.

[400exKy1e]

yup i dont really know what ur talkin about in the first part but im usin all the dynojet stuff

[cals400ex]

if you want a better explanation, pm me and i will try my best. if you got it figured out, that is fine too.

[400exKy1e]

thanks for the help i got it figured out last night and its runnin great! i guess somethin was wrong with the needle or something because i am still usin a 170 just the dynojet 170 now and all the other dynojet stuf.. thanks again!