I have a 2006 Kazuma Falcon 250 i bought. It ran fine when I got it. The second time we took it out we ran it hard now it idle's ok but will not take throttle. It starts to take off but then starts to cut out. I changed the plug and cleaned the carb and it is still doing the same. If I screw in the air screw it gets a little better. Any help would be welcome.