I have a 1991 Kawasaki 650sx it starts every time but when i get past 1/8th of throttle it loses power and i would describe it as a "chugging" noise it is still running but it won't take off. the engine shakes around and bangs back and forth. i don't know if it is some kind of fuel problem i have tried adjusting the carburetor and i checked the spark plus and the spark. i don't know what to try next. any ideas will help thank you