just a quick question, 400ex carb [Archive]

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derekhonda

11-01-2002, 08:36 PM

im too lazy to look it up somewhere else.

Whats the stock main jet size? is it like 156 or 152 or something

and then also, if i have a full procirtcuit exhaust, anda K&N airfilter, and now that it is getting colder, should i jet up about two main jet sizes ( like a 156 to a 162?) and then play with the air screw? What are most of you guys running who live in indiana with exhausts and airfilters?
Thanks

cheetah

11-01-2002, 08:41 PM

I thought it was a 148.:confused:

derekhonda

11-02-2002, 03:48 PM

anyone know for sure?

Bean

11-02-2002, 03:51 PM

its a 148

derekhonda

11-03-2002, 09:32 AM

thanks guys, now what size jet are you running for the winter (and have exhausts and filters?)

cals400ex

11-03-2002, 10:09 PM

i didn't quite understand if you already rejettted the bike or not. if you are running the bike with the stock jet with the pipe and k and n then you will be running lean. i would probally start out with a 155 or 160 and see how that does. most say to start out rich(bigger mainjet) and keep dropping down until it does not miss at full throttle. these main jet #'s are keihin #'s not dynojet #'s. the skrew is for under 1/4 throttle. if you are having problems starting the bike you could try to go counterclockwise with the skrew 1/2 of a turn or so. the other option for hard starting is just get a bigger pilot jet. most people recommend around a 42 pilot.