Pull carb to rejet?

[SaboTron]

The tech article shows pulling the carb to change the main jet on a 400EX. Can this be done without removing the carb?

[bradley300]

just try it. loosen the hose clamps on either side, and see if you can twist the crb around to get at the main and pilot jet. i beleive you would have to take it off to get to the needle

maybe...the main jet is on the bottom of the carb it would be very hard to get to...pulling the carb off is not hard...take the fenders and gas tank off...there are 2 hose clamps at the front and rear of the carb...loosen them and pull the carb out...i can do this in about 10-15 minutes...if i am taking my time and looking for tools

Originally posted by bradley300
just try it. loosen the hose clamps on either side, and see if you can twist the crb around to get at the main and pilot jet. i beleive you would have to take it off to get to the needle

the needle is accessed through the plate on the top with the 3 very soft brass screw

[SaboTron]

Thank you for the feedback. If I end up pulling it off is there any servicing I should do? Does sediment collect? Is it helpful to spray down with carb cleaner? It is a 2000 with about 9000 miles.

[400expooner]

i just rejetted my 2004 400ex when i put a new exhaust on. you dont have to take your carb off. take your seat off. under the carb there will be a i think 7/8 bold take that off and that is where you jet will be.

[bwamos]

Originally posted by speedyquad
the needle is accessed through the plate on the top with the 3 very soft brass screw

On my 300, I replaced those with nice HARD (flat head) stainless steel screws. ;)

[2004exrider]

I never take anything off my quad to do it? Alls i do is get a 17mm socket and take off the cap on the bottom of the carb. I've never had to take the plastics off or the carb.

Jimmy

[400exstud]

^^^I thought about doing that but how do you get the jet in and out without messing with the jet seat?

[2004exrider]

Ive never had a problem with it trying to come out.

Jimmy

[Mobile Dyno]

Jetting is not just changing the main!! You have to change the needle setting and the mixture screw setting. The only way to change the needle is to get the carb up out of there.

[400exstud]

Mobile,
I am getting so pissed at this thing. I have the full HMF, quiet core, lid ON, and a K & N. I put it from a 160 to a 155 and when I changed the jet it wouldn't start so I also changed the plug and man was that thing white/gray. I have heard that this means nothing because I was just riding and not doing plug checks but I have never saw the plug any color but black.

The bike runs better with the 155 and pops slightly when I let off because the air/fuel screw is slightly lean but why is my plug so damn white? Could it be the needle? I didn't think that I would have to move the needle with only a full system.

[Mobile Dyno]

400exstud, Sound like you Lean down low to mid and Rich up top. I would raise the needle one notch(lower the clip). When putting performance parts on, you should check all parts of the carb. White plug is lean. Do you have a jet kit in? With what you have I would possably even try an 150 main because of the quiet core in and lid on. Find out were your needle is now and lift it one. How many turns on the mixture screw are you? I would try 2-2.5 turns out

[400exstud]

I used to have the needle one richer than stock but because I had a super rich main, they didn't compliment each other. Now that I have my main close to where it should be I can start to tell that my needle my be lean. That would explain the white plug considering that I ride mostly 1/2 - 3/4 throttle. I don't know exactly where my air/fuel screw is but I do know that it is a tad to lean.

Thanks again mobile.:D

[Mobile Dyno]

Not a problem:D Thats what I'm here for. Try the 3rd position from top on the needle and 2.5-3 turns out on the mixture screw.

[SaboTron]

Mobile,

You said you have to change the needle setting and the mixture screw setting.
I was putting in a 160 main because I added a slip-on exhaust and removed the airbox lid. Seems to be running great and with my limited knowledge of carb tweaking I am hesitant to mess with it. Any recommendations on the other settings?

400 ex