400EX Carb Jetting Problem

[HondaRacing23]

I have a 2000 400EX with a FMF Powercore 4 silencer and powerbomb header. I also have a K&N air filter with the outerwear. I have a K&N Jet kit and the specs are below

Stage One
146 Main with the adapter
38 Pilot(said to leave stock)
clip on needle is on 3rd position
Air screw 3 1/2 turns out(like paper said)

It runs ok like this until I get up to high RPMS and then its like BAH BAH BAH BAH like it doesnt want to go anymore or it is getting to much gas. The plug is Black witch means its to rich. I am going to try and turn the air screw on 1 1/2 turns and try that. Any other sugestion?

FMF said to use a 42 pilot with a 155 main. I tried that before i got the jet kit but never really payed attention the the sound while riding it so i might try that to. need some help peoples. :confused: :confused: :confused:

[250EXking]

just keep fiddiling with it til it runs fine. that whant most guys end up doing. try adjusting the main and needle first then the air mixture.

[HondaRacing23]

I have moved the needle to the 4th and it didnt run at all. I moved the needle to the second and it ran great but still did the same thing. any more suggestions? Thanks for helping me out too.

[kargaaro]

Change one thing at a time and try it out until it's right. I would personally set the screw at stock 2.5. Top end is using the Main Jet for gas. I would start there.

[Porkchop]

is the choke on?:ermm:

[howboutchaw]

HondaRacing23
sounds like your hiting the rev limiter
if not I know a 155 kenith main would be close
put new plug in if yours is aready black

[cals400ex]

i can't see how your plug is black. a 146 dynojet is similar to a stock 148 keihin. all of the other jetting is stock too. i say a 152 dynojet or a 155 keihin main. i would put in a 42 pilot. as for the needle, i don't know about the taper on the dynojet needles. for the stock needle and summer riding i think the 3rd (middle) position is just fine.

[HondaRacing23]

I dont think it is the carb an jetting. I have done just about everything you can imaging to the carb. I think it may be something else. It sound maybe like it is either leaking air or sucking in to much air. I dont have any holes in the air box lid and no holes anywhere that I can find. THe exhaust isnt leaking either.

If I have the bike pined at a high speeed in a high gear 4th or 5th and leave it pinned and pull in the clutch and let it out fast and do that repeativly it is like "BOH BOH BOH BOH" almost as if it is sucking in air. I dont know where else it could be sucking in or leaking out air? HELP!!! HEHE

[cals400ex]

possibly an ignition problem.

[HondaRacing23]

I dont think it has anything to do with the carb I think now it may be the snorkle. I think it is either letting to much air or to much out. I took the gas tank of and just let it run with what gas was left in the float bowl and I could here it plan as day just reving it up. The BOH BOH BOH BOH is from the snorkle. Is it supposed to make that kind of sound. I dont think my friends 400ex does. What would happen if I just tape the end of the snorkle off? Or is there a way to take it of completely. Or is there something else I can do to get rid of it if it is even supposed to do that. Thanks for helping me out guys. I really appriate it.:)