Dirt Rider Magazine

I recently bought a 08 yz 250f off cregslist. After i got it home i found that no madder what i couldent get it to run i would kick and eventualy it would fire for a seckond and die even if i pumped the throtle when it fired it would still stall. I then put in a sparkplug and tryed that and it didnt help. I after that cleaned the carb as i found it was all gunged up and from then on it ran for the weekend first kick, over the corse of a month of riding it on weekends it has once again become imposible to get running. I have only put 3 hours max on the bike scence the carb clean. Im new to bikes so all help will be apreciated