I'm looking for a good wire to tap into that is hot when the ignition is turned on near the front of the bike. I need to rewire my f4i headlight conversion and want a wire that can handle supplying power to my low beam HID when the ignition is on. Preferably, a wire close to the gauges/ignition switch. I dont know which wire is which. Thank you.

 

Better solution:

Get a automotive relay.

Run a heavy gauge wire from the battery, inline 10a fuse, to the relay. From the relay up to the low beam.

Tap a light weight wire into the rear license plate light wire.

Run that to the trigger side of the relay. Run a ground wire from the relay back to the battery.

This will provide full power to the low watt bulb, and avoid using under weight wires. It also minimizes the risks of cooking an important part. If you also want this can be a better way to power the hi beam... full power.

 

The relay is best option, but use the old low beam wire to trigger the relay. That way, when you press the starter button, it will cut off the low beam. Otherwise, you may end up not being able to have the juice flowing to the starter.

 

Good point - that's a pretty clever setup (how the starter turns off the lights when activated)

 

No, actually I dont want to use a relay. Because I have HIDs, I have to put a switch inline anyways so that they are off when I start the bike anyway, because it is bad to ignite them and have them turn off and on again. It will burn 'em out. So all I want to know is a wire that's hot when the ignition is switched on. Thanks though, guys.

 

Then you want a switch AND a relay.

The reason for the relay is get a heavy gauge wire, that isn't being used already. Also, you can put the appropriate sized fuse on it AND not overload an existing circuit.

If you don't want to do it the right way, tap into the horn or use the low beam wire.

The day time running light option flashes, the dash is very low wattage, you are using the high beam wire already... licence plate light is too low a draw, the rear lights would be insane... you don't want to play with the starting circuit.

Any other options? There may be an accessory lead... but that is often always hot.

 

Also - check the licence plate light. It may not get cut out when you start the bike - meaning it'd give you power when the ignition was on only. It is designed for low wattage, so it would require a relay and heavier gauge wiring... otherwise you may melt the hell out of it.

Parts and costs:

30amp relay - < $10
1 inline fuse holder - < $2
5' red 12/14 gauge wire < $2
5' black 12/14 gauge wire < $2
1 automotive on/off toggle - <$2

Total cost for doing it the right way... < $18. Seriously... it'll save you headaches later.

 

The red/black wire that feeds fuse's a, b and c. There's a number of ways to tap wires but I feel cutting and re-terminating a wire is best. But you could also just peel a little piece of insulation back and solder in another wire. Be sure to use heat shrink if you do that.

 

I agree with Woot all the way. You don't want to tap into a skimpy existing 18 gauge wire for this modification. An independent setup is better and safer...