400ex carb on 250x?

[efilnicafesin]

Someone was telling me that I should put a 400ex carb on my 250x. I have a high compression piston, exhaust, air filter, and a few other mods... Supposedly, the stock carb doesn't pass enough air to get full potential. Anyone running a bigger carb on the 250x? What jetting would you start with?

[400ex men]

my 1987 250X has got more suff the its a 293 kit cam etc... and more and i have the stock carb:) but it is bore:)

[cals400ex]

there are several people who run the 400ex carb on their 250x's and 300ex's. most people that i talk to run around a 150 keihin mainjet, stock needle clip position (3rd position), and anywhere from 38-42 pilot jet.

[stonerider250x]

i bought a 400ex carb for my 250x and never could get it jetted right im not sure if its because it was on a 440ex and had the choke removed and all. But i have heard from other people that they ran great. i decided to not worry bout it and just got a Kehin PE series:cool:

[efilnicafesin]

Thanks for the replies... So it would be a worthwhile investment then or am I looking at headaches?

[fastkid400]

i would highly recomend it, for the money it was a great investment for me. i could tell a big difference, and it wasnt a pain to install either, bolts right up, but u have to either strech out ur stock airboot like i did and get a bigger hose clamp, or u can get a 350x airboot, i got one but i think it isnt a 350x cause it wasnt close. but neways, yeah i could tell it was worth it, :eek2: im running the mods in my sig, with a 142 main K&N jet size

[efilnicafesin]

Originally posted by cals400ex
there are several people who run the 400ex carb on their 250x's and 300ex's. most people that i talk to run around a 150 keihin mainjet, stock needle clip position (3rd position), and anywhere from 38-42 pilot jet.

Thanks... I'm looking at a Keihin kit right now, and of course they go from 140-150 and 150-160... Would you happen to know if it is on the high or low side of 150?

[nemesis]

We are still waiting for my brothers 400ex carb to come in. I'll let you know how we end up jetting it.

[efilnicafesin]

Well, I got the carb in the mail yesterday. Hoping to throw it on this weekend. I guess I'll just pick up a few jets to start with.

[sjc115]

Does the 250x throttle cable work with the 400ex carb? Or do you need to get a 400ex throttle cable?

[fastkid400]

mine came with the 400ex cable and its the same as a 250/300's cable. all u have to do is change it at the throttle cover. that was prolly the biggest problem i had, but no biggy:rolleyes: