I know. I've already done the GPS thing. But I wasn't happy about the wiring arrangement. It worked OK, but I didn't like the thought of having it hooked directly to the battery, albeit with a switch between the two. I needed to find a wire to 'T' into that goes 'hot' with the ignition. The headlight nacelle is a birds nest of wires and I didn't want to go in there. I've wrestled with this over the past year or so.
Then, a revelation!
Reading a post on the Royal Enfield forum, some bright spark pointed out that the horn goes hot with the ignition. That wire is easily found. Actually, there are two wires to the horn. One is live and the other is an earth, which goes to the horn button. Two minutes with the multimeter and I'd identified the one from the other.
I stripped out my original GPS set-up and simply re-routed the cable down the front of the frame and cut to length plus a bit. I clipped the horn wire and married the two 'hot' wires in a cable clip.
Obviously, this can't be done on the earth side, otherwise the GPS would only work when the horn was being sounded, so I needed to find a good earth connection. Luckily there is a threaded end of a bolt protruding from my crank case so a simple connector could be placed there. Not being able to buy such a thing, I made one from a piece of thin steel plate and set it fast with an 8mm nut.
All connected up, I placed the GPS in its cradle on the bike and turned the ignition on.
Success! All works as it should.
I've since covered the connectors with shrink wrap. Looks really tidy now.
Here's a few pictures of the wiring..