300ex breaking up

[ATC350X 85]

01 300ex w/ white bros e-series, 5 discs, UNI filter and at least 15 holes drilled in air box lid. I am running a 40 pilot and a 124 main, I believe the main came from a k&n jet kit, (i just bought the bike). It breaks up around 3/4 throttle when riding. I would like to run a Keihin main in it, what is a good size to start with? I have to do a plug chop to it still but what should i look for as far as the breaking up at 3/4 throttle? Any help is appreciated

[ATC350X 85]

anybody?

[james7734]

Check your pilot jet. I had the same problem when I first bought my quad used. tried everything including new hi rev cdi box. I checked the FMF web site for the correct jet settings for my megamax exhaust and low and behold, the jets were way off. Now she runs like a bat out of hell. Just thought I would throw that to you.

James

[Sjorge450R]

A 124???? ARE YOU NUTS? unless that is a dyno jet jet your way too lean. The 3/4 part of the throattle is controled by the main jet. With that many holes in the box along with the pipe you should be at like a 128 kein jet.

[ATC350X 85]

Its from a K&N jet kit. Def not a Keihin jet. Im gonna mess w/ it tomorrow. I do want to put a Keihin jet in it.

[bwamos]

K&N uses DJ I beleive.

The 124 is still to lean. You want either a 128DJ or a 132 Keihin. That should fix your breaking up up top.

You also want the needle clip in the 4th slot. (slot 1 being the one at the top of the needle).

Stock pilot is fine with the air bypass screw @ 2-3/4 to 3 turns out.

[ATC350X 85]

Sounds good, Im gonna look into it more tomorrow.