Horn

[Rat Fink]

I was out riding on Sunday when I flashed my headlight to warn an oncoming bike of a speed camera.
My horn started making short regular beeps. Nothing would make it stop.
I tried flashing the lights again wiggling the horn button then turned everything off. In the end I had
to disconnect the wire to stop it. Any clues as to what caused it are welcome.

[FJmonkey]

The horn wire is HOT when the bike is on, could be a short. I would recommend taking the switch apart and give it a good cleaning. It can't hurt and you will know that it is clean.

[Flynt]

Does the bike have an alarm of some sort? 

[Rat Fink]

Finally found time to check out the horn. Plugged the wire back in and everything was fine. Poked Prodded an wriggled everything to see if it would play up again. went for another short Sunday blast only 120Ks no repeat of the problem. I will pull the switches off shortly and have a look because now the right hand indicator doesn't always work and I have to indicate left before it will work again.

[Pat Conlon]

As Mark said, the 2 wires going to the horn are hot, and the handle bar switch just grounds the circuit, activating the horn.

On the 2 wires going down to the horn,  one is the power leg and the second wire is the switch leg, going to your horn switch.

What I think is happening is the 2nd wire, the switch leg wire, is shorting out to ground, causing the horn to beep.
This is common, the horn is mounted to the lower triple clamp and moves back and forth with the forks...and the wires rub against steering neck every time you turn the handlebars.

This rub is where the short will be...on the switch leg..If it were on the power leg you would be blowing a fuse.

I would not worry about the handlebar switch until you look closely at the horn wires at the steering neck area.