Dongfang 150cc scooter problem

[smithkjnc]

Hello. Just purchased a 150cc sunny sports dongoing scooter. It had been sitting for about 5 years. Had to fix various things on it, but now having a problem with it running. Changed gas, new gas filter, adjusted valves, new hose's ...now, it starts and idles fine, but as soon as you open the throttle, it starts to miss and die at anything over 2500 rpm. You can hold it wide open and it misses, and barely runs, let off the throttle and it returns to idle and runs just fine. I have cleaned the carb several times and cannot find anything to cause the problem. I am stumped. ..any suggestions on what to do next?