Fresh 426 jetting?

[torqen2k1]

I recently got my 04 400ex rebuilt. I was wondering what main jet size, pilot,and what clip to lower. I have :::: Weisco 426 11:1, Port Polished head, 3 angle valve job, HotCame Stg 2, open air box with proflow kit/Uni filter,Yosh full exhaust

[cals400ex]

with those mods besides the head i ran a keihin 160 mainjet, needle clip in 4th position from top, 42 pilot jet, and 3 turns out on the fuel screw.

[torqen2k1]

I seen some people with 426 runnig a 170 main. 42 pilot is that good or no. Should I good bigger?

[cals400ex]

you can run a 170 if you want. i don't in mine though. the larger you go, the more top end you lose. if you rather be a little big vs a little small you can put that in and it will run fine. a 42 or 45 pilot is what i recommend with the stock carb.

[torqen2k1]

what should the fuel mixture screw be at? is 2 1/2 turns good?

[cals400ex]

Originally posted by torqen2k1
what should the fuel mixture screw be at? is 2 1/2 turns good?


this will depend on your pilot jet size. with a 42 pilot jet i would try around 2.75-3 turns out.
with a 45 pilot i would recommend 2.5-2.75 for starters.

just remember, as you mod your bike, as the temperature changes, as your change your altitude, etc, your jetting will change too.