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View Full Version : Jetting help!!!!!!



Fenix169motox
11-22-2007, 11:01 AM
hey everyone i have a lot of carb trouble on my 400ex... go figure right?
lets start with the basics. as of right now i have a TC stubby, stage 2 hotcam, 12.5:1 piston. in the carb the needle is in the middle or 3rd notch from the bottom, i'm pretty sure the main jett is a 168 ( its been a while since i;ve had it apart.. )

at idle it runs really weird, i had to turn the pilot screw 3.5 turns out and my idle adjuster is all the way up, before it'd idle really bad and if i choked it she'd run a little better, so i figured it needed more air thus the 3.5 turns..

yesterday i had it in the yard and i was ripping around the yard and it was really hesatent (sp?) when i was accelerating, like it was sputtering and was pathetic.. so i took the air box lid off, ran better but it still didnt seem right.. like it wasnt all there..
so what set up should i go for? like jett size and needle clip position.. im in the powersports institute and im in fuel class right now so i konw whats up but we havent done anything in class yet about tuning, everything they teach is for stock applications...

any help is much appreciated thanks guys!!

boosted3g
11-22-2007, 07:51 PM
do you still have the stock pilot in there or not? I live in PA and its getting cold, i see your in ohio. Sounds like you need to jet it up and maybe raise the needle some. If your still on the stock pilot that deffinantly needs to be increased. Was this a drop in piston or did you overbore?

Fenix169motox
11-25-2007, 01:49 PM
honestly i have no idea if its got the stock pilot jet, when i bought it she has an fmf and a K&N and they told me they jetted it, but also told me that it was bored 30 over, (its not, lol) but im just tryin to get it dialed in for next season, i raised the clip one notch which lowered the needle and it ran really bad, if i take off the airbox it gets better but its always done that, it hesitates when its on still.. and so its not bored out, but just high compression with a stg 2 hotcam