i have a 2003 400ex and it has been sitting all winter. i started it up the other day because i plan on going riding in a few days. it ran fine and then cut out and died. i tried to bump to idle up a little bit so it would keep running while it warmed up. i ended up breaking the cable the goes between the remote screw and the screw on the carb. i dont see how this would cause the problem but i dont know. The problem im having now is that it wont stay running unless the choke is on. Also, when i try to ride it, it does fine with just a little bit of throttle, but when i give it too much it bogs down and and wants to die. Just wondering what may cause this. I thought it might be bad gas because it sat there all winter. I put some gas additive to try to get rid of any water that might be in there, but no luck. i'm going to drain the gas tomorrow and get new, hopefully this will work. any ideas or suggestions will help. I just rode it about a month ago and it ran fine, now it doesnt run and i havent done anything to it. thanks for any help.

 

Its your carburator Mine did the same thing well my trike clean the carb maybe get new carb kit and it should be blasting in no time if your going to let it sit for so long drain the carb so that it dont get dirty.

 

You probably dont need any kit. Just clean the jets, and the crud in the float bowl.
And I agree, ...next time you know its gonna sit for longer than a couple of days, with out being started, turn the gas valve to off, and then idle til the motor dies.

 

It seems like it would be kind of a pain to get that carb out of there. how is it?

 

Not that bad, the plastic sides and gas tank can be removed and then theres plenty of room.

 

i took the carb off today and sprayed a bunch of carb cleaner in there. i didnt strip it all the way down, but took off the bowl and the other plates on it and im still getting to same thing. i also noticed that there is some white smoke coming out of the exhaust when i rev it up. i know bluish smoke is oil, black is fuel, and white is usually water. but there is no water being air cooled. i keep check the spark plug and it keeps getting black, but im sure its from being on choke all the time. the spark plug is sparking fine. just wondering if i should do a more thorough cleaning or if anyone else has any suggestions. thanks

 

Tear the carb apart and clean out the jets... it's the only way.

 

your white smoke is prolly jsut cause its winter and its cold, and yeah you have to clean out the jets, mine was having the same problem, just take all the jets our and shoot carb cleaner throught then and you should find all kinds of crud come out

 

While you're in there, make sure that you remove the jets and look through them with a flashlight and magnifying glass to make sure they are not obstructed... if you don't see a nice little round spot of light, run a small strand of copper wire (that you can separate from a piece of stranded wire) through the jets along with carb cleaner, then blow them out with compresser air or canned air to remove the gunk that's blocking light.