carb problems, with my 2002 yamaha yz250f seems to be a simple problem maybe a rebuild

[Alexei N]

kit is needed? ok i bought this bike recently, it had a new bottom and top end and clutch rebuild done (it has about a half hour total on it),,, ok problem : bike wont run woth choke turned off, i also have to turn the gas on full for it to start , once i have it started i turn it down to make it idle normal, after that i let it run for about 2 to 3 mins then i turn the choke off and the bike dies just like that, i have taken the carb apart and cleaned it twice, i really dont know whats wrong with it now? help me please