What jet size to use?

[howshnazy]

what jet size would i need if i have a stock 400ex with:

no air box lid

no airbox lid and a k&n filter

[LazeR]

What is your elevation ? Are you going to use Keihin or Dynojets ? When i had a K&N Filter and no air lid, i went up one on my main, but i was using dynojets, so you if its keihin i would try one or 2 sizes up

[efilnicafesin]

What is the stock jet size in a 400ex? Are jets interchangeable from the 250x to the 400ex carb? They are both Keihin carbs..

[mojoe2878]

stck main is 148

[efilnicafesin]

:eek2: Damn.... I just picked up a 400ex carb, and I looked at the main.... it is a 120.... WTF uses that??

[mojoe2878]

Originally posted by efilnicafesin
:eek2: Damn.... I just picked up a 400ex carb, and I looked at the main.... it is a 120.... WTF uses that??
maybe they had it on a 300 or 250... i know it didnt come off a running 400 with a 120 main though.

[howshnazy]

umm i'm at real low elevation, like < 1000 maybe even less than 500. I think keihin...whatever they have at the dealership :confused:

[efilnicafesin]

Originally posted by mojoe2878
maybe they had it on a 300 or 250... i know it didnt come off a running 400 with a 120 main though.

Cool... Thanks... I am going to be putting it on a 250x and I thought I needed to be closer to 140 main....

[LazeR]

I'd say 140 for a 250x would be to much, i would try like a 120 or so, let us know how it goes

[cals400ex]

on a 250x i would start around a keihin 148. that seems like a good starting point for most people. however, i have never tried it.

on the 400ex, i would try a keihin 152 mainjet