Ultima Plus Wiring Kit

I don't think the horn or start button could be wired with power. They are "ground" buttons. When pressed, the wire attached to them is put to ground, into the button frame, then passing into the switch housing, into the bars, finally picked up by the black ground wire in the left switch and grounded to the harness in the headlight. So, horn power would need to be run to the horn, not the horn button. Starter power would need to go to the solenoid, or if you're retaining the starter cut-out safety relay, to that first. The relay will pass it on to the solenoid and also protect against starter engagement once the motor is running.

 

The solenoid earth side wire (blue/white) is what runs to the start button. When you press the start button, it grounds out and completes the starter circuit, activating the starter.

 

Any updates with the Ultima 18-533 and its use on metric bikes? Id like to see what your final wiring diagram turned out to be or at least which wiring did you have to change from what the ultima diagram suggested. I'm a wiring newbie

 

As far as the starter relay is concerned it don't care if the button is before or after, so it can be wired with power from the button to the relay R/W wire and just ground the B/W wire or as stock with power to the relay and the button after to ground the circuit.
On the horn you can do the same thing.As far as any other switches you will have to look at each thing the switch operates to determine if the power can flow either way.
The big thing is that the circuit be complete. Power, thing to operate, and a switch, enough wire to reach everything, then back to ground. If you leave any off these things out it won't work.
Leo