I hope this helps. First if the bike has had periods of nonuse you may what to try clearing out the idle port in the throat of the carb. This will be a small hole by the butterfly gate. If that doesn´t work there is a small receased screw on the side of the carb. You can try turning this a and test running the bike. make sure to only make small adjustments at a time. I believe that the problem you are having is in your air/fuel mixure. Also check the exhaust for an higher level of black smoke which would also indicate that the bike is running rich (to much gas). I´m not sure but your idle for the bike should be in the area of 250-500 RPM. Thats the curb idle I think. Good Luck and I hope that this helps you.