make sure all your connection little prongs that are in your wires usually theres like 4 or 3,make sure the uip top and not fallen down in the plastic,check the stator coil wires and the main switch assembly(where your key goes) unplug them and check to make sure there isnt any sunk wires that are causing little or a weak connection,also your ignition coil might be bad,you can do an ohms test on it i think.
