ok now what...

[Halter]

Well...I firgured out the sputter on top end...it was too rich..cause i took off airbox lid and she runs like PERFECT now...

soo... some local hicks said put some pantyhose over it where the airbox lid goes...I am like ahhh.... dont know..what should I do..I dont really wanna go get a new jet and rejet the thing again

[AR15 guy]

You could do that. Or get a K&N powerlid. Or simply leave the lid off.

[Halter]

well..I dont like that big Throaty sound when u get on it...will the K&N have that... uknow what I talking about??

[GPracer2500]

I'd just rejet it. If you ride year round, you should be rejetting for winter/summer conditions anyway. My point is that good jetting practices aren't a "set-it-and-forget-it" affair.

A main jet change on most bikes only takes a few minutes anyway.

[Halter]

a few mins??...well should I just go 1 smaller?... 158? or 155?..

takes longer than a few minutes..u gotta take all plastics off and stuff...unless u know a better way?

[exrider008]

it takes me 20 min to change my jet all i do is take the 2 bolts out of the plastic down by the seet, then the 2 rubber straps holding down the gas tank, then i lossen the 2 clamps, after that i just lift up the gas tank and just rip the carb out flip it over and unscrew the 3 screws on the bottom of the carb and chang the jet.

MAKE SURE U TURN OFF YOUR GAS!!!!

[GPracer2500]

To change the main on a 400EX you don't need to remove anything, loosen the carb, etc. Just remove the 17mm cap on the bottom of the float bowl with a small wrench. Then use a 6mm or 1/4 inch (mains are actually 6mm but 1/4 is almost the exact same size) deep socket to remove the main, install the new main, replace the cap, and that's it.

I use the small adjustable wrench and the 1/4 drive ratchet in the top of this picture. There is plenty of clearence under the EX carb to manuver. Simple and fast.

http://img231.imageshack.us/img231/3310/p62500054mb.jpg

Sometimes it helps to just hold the deep socket in your hand to thread the jet up and down, then attach the ratchet to snug it up. On some other carbs I use a short 6mm 1/4 drive swivel socket if the clearence is more limited.

[Eviltanker]

You could look at the Outerwears airbox cover.