250ex not running - HELP

[Jbolt]

OK, I bought a 2002 250ex for my stepson about a month ago.
From what I got from the original owner the quad spent allot of it's life in storage and was ridden very little.
About 2 weeks ago we had it out and it developed a sputter under load, then lost its power. We were able to finish the day out by pulling the choke out about 1/4 of the way, it seemed to run fine this way.
Last week he was riding it on our land and it did it again, but got worse. I pulled the carb off of it, tore it apart and cleaned it (was full of gunk) took the petcock off the tank, cleaned it and the filter put it back together - ran great for about an hour then started again.
Now it is doing the same thing, any ideas?

Need to figure out something quick, we are leaving to go camping tonight.....

Thanks

[bwamos]

When you removed the carb and cleaned it.. did you also remove and clean out the fuel line between the tank and the carb, as well as clean the filter on the bottom of the petcock?

If you do that.. and you're still getting issues with it going lean under load.. check to make sure your gasket seals on the carb didn't get hard. May need a new seal set.

[Jbolt]

Thanks-

Yes I cleaned the fuel line and everything else.
All of the seals seems to be plyable and in good shape.
I just got done tearing it apart and putting it back together again, I didn't find anything wrong, but it is running really good now