ive been having some problems when idling. when i take my bike out of gear the slightest twist of the throttle will make the bike rev into really high rpms. one time i thought the motor was going to blow. on the other hand it wont idle without giving it gas. ive tried to adjust the idling speed by twisting the little screw and have got it to idle but then after a short ride it was back to its strange behavior. the carb seems to be attatched tightly as well. does anyone know what might be causing this? im not sure whats going on with it but i hope its an easy/cheap fix.