250ex running bad! PLEASE HELP!!

[KD 428]

Ok my brothers 250ex will run fine for about 15 to 20 minutes, then it will start to studder. i cant figure out what it is. can anyone help me??

        thanks
             kenny

[MachineDog]

I find that I forget to do this all the time but, did you check the gas?

[KD 428]

yes it has a full tank

[Fox17]

not if it has gas but if the valve under the tank on the side is turned on. if its not it will cause that.

[Toomey]

Make sure that the gas cap is venting properly.  I know that causes short term problems, but I don't know about 20 minutes, so maybe it might be that.  Do you have one of those aftermarket gas caps with the real short hose and the one way valve thing on the end?

[Chuck_Norris]

when was the last time someone went through and cleaned out the carb?

[Alba450]

Check your air filter.  it might be dirty

[KD 428]

ill check out the carb and yes it is venting properly

[Yamaha72]

This is going to be a hard one to figure out.... My friend had an 01' Blaster a couple of years ago and we took it to Croom and he overheated it and like warped the poop out of it and it was doing the same exact thing, it would run  fine for about 15-20 minutes and then just stall and you just absolutely could not start it after.