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View Full Version : 400ex carb on 250x?



efilnicafesin
10-12-2004, 05:15 AM
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
10-12-2004, 09:27 AM
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
10-12-2004, 03:32 PM
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
10-12-2004, 05:23 PM
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
10-15-2004, 05:54 AM
Thanks for the replies... So it would be a worthwhile investment then or am I looking at headaches?

fastkid400
10-15-2004, 12:14 PM
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
10-19-2004, 06:55 AM
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
10-19-2004, 09:10 AM
We are still waiting for my brothers 400ex carb to come in. I'll let you know how we end up jetting it.

efilnicafesin
10-22-2004, 02:31 PM
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
10-22-2004, 05:23 PM
Does the 250x throttle cable work with the 400ex carb? Or do you need to get a 400ex throttle cable?

fastkid400
10-22-2004, 05:56 PM
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: