I bought a Roketa Bali 250 MC-13. It would not run right it had a flat spot during ex would cut off. I removed everything down to the frame. What I found was a vacuum line at the carburetor about 3 in long. You can see it by looking down at the top of the carb. I removed that hose and plugged the vac port at carb not the dash pot and it runs perfect. I'm getting about 70 mpg and no other problems.