02 250 starts and then sputters out

[Wijohn]

IMO: I am far from an expert, I have only worked on carbs once my whole life. But I am thinking that when you commented that the bike is dying when you come to a stop that maybe you have a pilot jet in the carb that is getting plugged up. If you have the service manual downloaded look for the pilot jet's location. Watch a couple videos on YouTube. Pulling the carb is not too hard to do. The pilot jet has 2 holes in the side of jet and a main hole running through it. All need to be clean. If plugged up, soak it in cleaner for a day or two before trying to clean. The only other thing I can think may be a problem is your choke cable, my bike acts the same, starts with no choke on. I haven't got around to replacing it so I can't comment on that.