I have a 2009 kawasaki klx250s. After starting the bike and warming it up to the recommended time in the manual as soon as i go to accelerate the bike it hesitates and the rpm's will back down sooo far to pretty much nothing. After the bike has been warmed up from a ride it won't do it anymore, just seems to happen on start up after initial warm-up. Also at just idle... by hitting the accelerator the bike will stall right out. I have taken it into my dealer and they took the carb off and cleaned/checked it got the bike back wasn't doing it then a couple days later i went to ride it and the problem came back like mentioned above. I have changed my spark plug as well. What could it be, electrical? carb still?

Just a thought, it might be more like the choke, slow speed jet, or high speed jet mixing with choke. It will run, but will run rich, and possibly cough. I don't even let the bike warm up, I just hit the road, and a lot of times I get 10 miles down the road and realize that the choke is still on. Oops. I had a KLR 250, totally different bike, about 200HP difference. I couldn't believe how fast the klx is compared to the klr. Hope this helps. Just a thought, it might be more like the choke, slow speed jet, or high speed jet mixing with choke. It will run, but will run rich, and possibly cough. I don't even let the bike warm up, I just hit the road, and a lot of times I get 10 miles down the road and realize that the choke is still on. Oops. I had a KLR 250, totally different bike, about 200HP difference. I couldn't believe how fast the klx is compared to the klr. Hope this helps.