I just purchased a 03 400ex this past week. I also have a 300ex and when I start the 300ex I do not need to use the choke or anything. I just turn it over let it idle on its own and it warms itself up. But with my 400ex it likes to stall ONLY when the engine is warming up it seems. Once the engine is nice n warm it'll sit and idle all day. I have to keep the throttle a little bit above idle for it not to stall out. Seems like choking the motor fully does not help BUT half choke does seem to help. What do you guys suggest? I am running some Sea Foam through the gas tomorrow and I am thinking about taking the carb off and having it cleaned since I know the P.O. did not ride it much at all. The engine is completely stock by the way. Should I up the jets at all to help? I have never played with jets before and am not too sure what jets to bump it up to on a stock motor.