help jetting 400carb on 250x!

[whtknckleracng]

hey guys i just got a 400carb im gonna try on my 250.
my motor mods consist of the following: 12:1 weisco, mild port, web cam, full tc pipe, hardened rockers, heavey clutch and valve springs, .20 over, k/n filter. help will be greatley appreciated thanks!

[cals400ex]

as a guess i would try a keihin 150 mainjet, needle clip in 3rd position and 40 pilot jet.

[ghak99]

Originally posted by cals400ex
as a guess i would try a keihin 150 mainjet, needle clip in 3rd position and 40 pilot jet.

That is a very good place to start. I will warn you though, you will have to have this carb jetted perfect in order for it to run correctly. It took me forever to get mine right, but now that it seems to be jetted correctly, I feel it is a good mod per dollar spent.

Good luck!

[stonerider250x]

i never could get the one i had jetted right:( . its ight tho i got a new kehin 38mm carb on the way:D

[whtknckleracng]

kewl thanks for the info guys
now from what i hear this is gonna increse top speed?will it take any power away?

[ghak99]

Originally posted by whtknckleracng
kewl thanks for the info guys
now from what i hear this is gonna increse top speed?will it take any power away?

I really noticed my quad came off the line faster and pulls alot harder out of the corners. I was looking for throttle responce and that is exactly what i got, and it may have helped out a bit on the top end too. I also took the choke out of mine, my motor has never needed one to start anyways, always starts on first kick! I don't think I lost any power at all, but I have a few mods. I would guess it would not be a good idea on a basically stock motor.

[whtknckleracng]

yeah i wouldnt even be thinking about doing it if my motor was stock. the kid that had my quad before me ran the 400 carb on the x and didnt change the jetting at all. the 400 carb has a 148 main so thats pretty close. i guess ill just have to see.