Its either ignition timing,box,or battery.Check to see if the plug is firing at 28BTDC.Check battery voltage.If ya dont know how to check timing go to ch-ignitions and look at instructions.While your there see how much his or rcexls are in case yours is bad.What i would do first is call the dealer and ask him to send ya a new box if your timings fine and tell him youll send your old one back.