What is the problem?

[Steve181]

I have a 2001 yz250f

it will fire up and run fine on the choke

but once the choke is turned off it will stop running if you do not give it any gas

i tried ajusting the idle, cleaned the carb.... but had no effect

[zuch95701]

something still pluged in the pilot circut. Or the carb halve gasket has gone bad. It is very risky to replace the carb half gasket. I would try a new pilot jet and clean the passage way very well. Also your air fuel screw o ring might have came off. If you pull your air fuel screw out there will be a spring, flat washer, and finally an o ring.

[ronbuell]

Sounds like it could be an air leak too. Spray brake cleaner or WD40 around the carb boot joining to the head and see if idle speed changes... it should not. My next place to look would be the hot start. It could be stuck open. Remove the plastic part that screws into the carb and make sure that when you pull the lever, that it works back and forth on the cable AND that the spring that pushes it closed is in place. If not, mud and crud is jammed into the cable so clean the cable and lub it. Also check the rubber seal on the end of the plunger. That's what seals the Hot Start inside the carb. If that's not sealing, that will cause it to stall. A lot of times the plastic part that screws into the carb body will strip out and not screw down all the way... and that will cause it to leak. ZipTie Racing makes a billet replacement that is great. If you have no air leaks, then the carb can be dirty and need cleaned out, that means all passages and jets open, not clogged up.

[Dano426]

Make sure that when you clean your carb you use a air compressor and carb cleaner. I cleaned my carb twice with out it getting better and some one said to use a compressor. Worked like a charm