Every time i start up my bike when its cold i hear the engine struggling to keep it self going then after a few seconds the motor starts to smooth out. However this isnt the problem. The problem is when my bike it cold it has trouble reving up. a quick twist of the throttle and the engine shuts off. but if i do it slowly, once i get it past 2k rpm its ok. but initially 0-2k rpm is a struggle when the bike is cold plus if i twist it too quick the engine shuts off. Does anyone know what the problem might be? Oh and after about a mile of riding the problem goes away.