The white wire should be routed through the kill switch. When the kill switch is pressed, it connects to the white wire (a low voltage) through the switch to the wire that should be bolted to engine electrical ground. When the kill button is pressed, the low voltage shorts to ground and kills engine spark. In simple terms, connect the "other" wire out of the kill switch to a bolt on the engine. Some riders send the blue wire (a high voltage) through some kill switch. I expect the low-voltage kill switch to burn itself out someday if using the high-voltage blue wire. If that happens, you will never get spark until you replace the switch. If you are going to use the blue wire through a kill switch, wrap some insulating electical tape around the end of the white wire to prevent it touching the frame or the engine, and killing your spark.