If you look at the coil mod diagram, there is a trigger. If you do a headlight using an automotive relay, you also will need a trigger. The trigger needs to be SWITCHED 12VDC from the ignition switch. Use any brown colored wire associated with the reserve lighting or turn signals. This is a SWITCHED 12VDC wire... splice into it for the trigger. You will turn on the key and it will close the relay. You will turn off the key and the relay will open. The problem with using the "headlight" as Roy suggested is that the power TO your headlight comes from the blue circuit which makes contact with the red/yellow and red/black lines in your your hi/lo beam switch... in other words, the blue and red/black touch in the switch, the power from the blue circuit goes through to the red/yellow wire and from there to the low beam via a couple connectors. Same is true for the red/black which powers the low beam I think (I might have the hi and lo beams' colors backwards...)... ANYWAY, if you were to pick off the blue wire for the trigger, it would work BUT you would have to run a long wire from the left switchgear or the connector area back to the relay which would be awkward. The blue wire generally comes from the RIGHT hand switchgear if you have an on/off type switch on that side. If there is no on/off where the bike's headlight is on all the time, I think it MIGHT come direct from the fuse area via the ignition switch.