400ex carb issues? popping with throttle and fouling plugs

[drhill]

Ok,

I recently bought a 2004 400ex on the cheap - it's been sitting with old gas for almost 2 years. I though, hey clean out the carb and fire it right up! No such luck. cleaned out the gas tank, replaced the petcock(brass tube had a hole rusted into it!) cleaned out the carb thoroughly, replaced the float valve and it will fire and idle but it will die if I give it any gas, unless I slam it wide open then it misses and pops through the exhaust and will not return to an idle - it just dies. If I leave the petcock on, it will eventually leak gas from the overflow tube after about 5 minutes of sitting. Also - after trying to run the bike like this for 20 minutes or so the plug comes out black and sooty.

What should I do?

I think I have a bad seal on the float valve, I tested it by blowing into the fuel inlet and it will seal, but the seat in there could be corroded or roughed up because of the old gas.

Slow jet is 42, main is 152 or 155 I've tried both. HMF slip on and k&n filter, tried it with airbox lid on and off...no diffierence in this issue.

Forgot to mention: there is no rubber gasket under the top cover on the carb (where youwould go to remove the needle) it was like that when I got it...seems to seal well - could that be a problem?


Thanks for the help!