jetting on my 400ex

[Catfish26]

I have a 400ex with white bros e-series slip on, K N air filter with vented airbox. It is jetted but the guy i bought it from didnt know wat size jetting it had. It seems to be hard to start so I was thinking maybe i need to change it. What size jetting would be best for this setup.

[zephead400ex]

Welcome to the site bro:D

Is it just hard to start? The stock jet is a 48 pilot. If the jet is still stock, go to a 52 pilot.

After I installed my 51 pilot, it is MUCH easier to start.

Good luck

[cals400ex]

stock is a 38. most go to a 42. this should help for starting. i think zep just got his #'s confused. also, i didn't even know they made a 51 pilot jet??

[Catfish26]

ok.. which #'s are right cuz now im confused. I forgot to tell u that when i first got it, it did not have the airlfilter. It was only after i bought it that i installed the airfilter. Could this be the problem? And does it matter that i took off the airbox cover? Also how will I be able to tell if im running too rich or not rich enough? Thanks

[mojoe2878]

cals is right , the stock pilot is a 38

[cals400ex]

we have some issues here. your joking about the air filter right? :huh

make sure change your oil and filter if nothing else.

you need to open up the carb and see what jets are in there. here is the stock jetting:

mainjet--148 keihin hex
pilot jet--38, it is a series 21 keihin
fuel screw--2.25 turns out from lightly seated
needle: keihin B44A
clip position--middle position (3rd notch)