The diagram shows an 'opitonal' method of wiring the kill switch using the white wire. I don't agree with that method but many have done it and it seems to work for most. The kill button (normally open momentary switch) simply connects the two wires coming from it. The black wire from the engine is grounded internally to the engine. The blue wire ( output about 80 volts) is the ignition primary lead. When you wire the kill button as per the diagram what you are doing is grounding the blue wire when you press the button therefore shorting the ignition to ground and stopping the engine. The white wire (output about 6 to 9 volts) can be used for a low wattage headlight but it is limited to about 2.5 to 3 watts. I hope this answers your question.in your diagram you dont have the white wire being hooked up to anything, Why? I was under the impression that the white wire was basically your hot wire? how would you get anykind of spark to your plug if its not hooked up to something? Mine is wired in with the two blue wires ( thats with no kill swithch) and/or you could wire it to the yellow wire of the kill swithch and take the other wire and tie that in with the ground
Tom