Removing choke, really worth it???

[Maxxed out]

It says on here that you can remove your choke and put in a 42 pilot jet. But wouldnt that make your 400 run like crap on trails becuz it would be running so rich?? :huh

nope,,,pilot jet is at the bottom of the fuel circuit..mainly for starting and idling.

Mines had a 42 in for about 2 years and no problems only good things...:cool:

[cals400ex]

i had my choke out but i recently put it back in. with it out some claim you gain a little throttle response. whether you do or not, i don't know. i put it back in because it seems as if i lost a little top speed with it out. i could be dreaming but that is just how it felt. i rejetted numerous times without out any success. i can't compare how it ran with it out to how it runs with it in now because i am building a 406. i am wondering if the choke on the inside of the carb acts as an air deflector and produces more top speed.:rolleyes: i am sure there is no difference but my bike doesn't seem to be running as good as it use too so i will see it runs when i get it back together.

[PHIL_B54]

the engine builder i got my cam from told me to leave it in, he said it straightens the air flow and directs it better. but until someone proves it , no one will know either way.

[cals400ex]

Originally posted by PHIL_B54
the engine builder i got my cam from told me to leave it in, he said it straightens the air flow and directs it better. but until someone proves it , no one will know either way.


this is the same thing that i was wondering. like you said though, i can't prove my point.

[Maxxed out]

Originally posted by Rico
nope,,,pilot jet is at the bottom of the fuel circuit..mainly for starting and idling.

Mines had a 42 in for about 2 years and no problems only good things...:cool:

It says on this site than the pilot jet is used for idle to 1/8 throttle. I use 1/8 throttle on tight trails sometimes.. Are you sure it wouldnt affect it?

[brianC400X]

I removed my choke and put in a 42 pilot jet in on my 01 400ex. It seemed like a gained midrange torque but I havnt been able to get it too run right since. I lost alot of power right off idle. It ran alot richer. I'n tight trails it is worthless. I brought a screw driver on one of my trail adventures and eventualy got the airscrew to where i wasnt way too rich but lost power in the midrange and upper rpm's. I'm changing it back to stock tomorrow and going to Bronco Fest on sunday.

[Maxxed out]

Yaa thats what I was afraid of. Maybe I wont take it off after all. Thanks!!

[cals400ex]

i ran with a 42 in without taking out the choke. yes, the pilot is for the bottom of the fuel circuit. if you have no engine mods or airbox, a 40 pilot might be better for you. if your running too rich with the 42 in you need to first try turning the fuel skrew in some. just make sure your running rich at really low throttle positions and not at mid throttle positions because that is your needle. you should not be losing power with a bigger pilot in if its the right size pilot. my bike ran great with the 42 pilot in when all i had was airbox mods. if your bike is all stock, i would either put in a 40 pilot or move the fuel skrew out a bit. your 400ex is jetted lean from the factory.

[brianC400X]

do the jets come on sequentialy and stay on?
example: your pilot jet comes online and keeps on working as your needle comes onlie and keeps on working as your main jet comes online

[cals400ex]

check this out:


www.exriders.com/techarticles/jetting.html