2004 carb

[rsimmons_82]

does anyone know if the 2004 carb is different than any other carb that comes stock on a 400ex? ive heard its slightly bigger, but i dont know what to believe.

also, i have a completly stock bike. all ive got is a k&n, airbox lid removed, and the resonator cut out of the stock muffler. with that being said, sometimes its a littler hard to start and backfires a little (is this from a pilot jet that is too small?). next problem is that i check my plug the other day and knowticed that it was all carboned up (looking like its a little rich).

i supposed to recieve my full hmf exhaust sometime next week. i was just wanting some advise that might be helpful when dealling with this carb problem. (should i just change the plug and put the new exhaust on then see what happens, or should i change my jets first)

[K_Fulk]

The 04 carbs are the same as the older carbs.

Jet you carb whith the recommended jets when you put your pipe on. If you dont your starting problem will only be worse. And change the plug while your at it.

I dont know what they recomend but a 155 main and 40 pilot wolud be a good start.

[JOEX]

does anyone know if the 2004 carb is different than any other carb that comes stock on a 400ex? ive heard its slightly bigger, but i dont know what to believe.
Last bit I heard was that the 400ex carb has an oval bore and the earlier spec was the average of the two demensions. The newer spec is the larger of the two demensions.

Damn marketing departments:mad:

[nitehawkqb]

First of all..............he is right, the 2004 carb is the same size as the other year models. Do not change your pilot jet, it has nothing to do with the function of the main jet or the needle jet.
Your 400 is running too lean, that is why it is back firing. If your bike is stock and you have introduced all of this air flow, ie; air box lid removed, aftermarket air filter, taken out the guts in the stock tail pipe and you have not increased your fuel supply with increased jetting..........................you are running too lean.

Leave the air lid off, leave the after market filter, install your new exhaust system with a Dynojet kit. go ahead and install the new needle jet at the third position and the 165 or 170 main jet and have fun with it.

I have the same bike, trust me................it works!!