Found this modification on Chet's Valkyrie Page.

I removed the gas tank so that I could reroute the horn wire along the main wiring harness. To reach the new location, I needed about a 13.5 inch extension wire, which I made.

Here is the ends of the new horn wire extension.

Turns out that when I added the Big Bike Parts horn cover, I wasn't going to be able to get the horn back in the stock location without moving the radiator out of the way. This seemed easier and looks better. (since I already had the gas tank off)