Fitting an additional horn

Having read other threads about problems fitting an extra horn to the 1200GS, I decided to try it myself.

First, I did some investigating.

The first thing I noticed is that the OE horn has a funny connector - not spade terminals. So this makes it harder to do a clean job, as normally I would make up some Y shaped wires with spade terminals on to split the power off to the new horn.

The two wires going to the horn are: brown (earth) and green with a stripe (12v). I confirmed with a meter that the live is switched - that is to say, with ignition off, there is continuity between the brown wire and the frame.I also confirmed that, with the horn disconnected, ignition on and the horn button pressed, the bike supplies power for a fraction of a second and then cuts it, presumably detecting a fault in the circuit.

I started thinking about relays - someone else posted here a while ago that they had tried a relay in parallel with the OE horn, and the bike didn't like it (to the extent of cutting the power). But I thought I'd try it anyway. Then I thought, lets see if the bike will happily drive my new (louder) horn with the OE one disconnected.

So I knocked up a connector - see picture 1. The red wire is joined to the switched live (green/stripe) by one of those splicing block thingies. The confusingly coloured green/stripe wire is connected to the frame. The red spade connectors are to attach to my new horn.

Surprisingly it worked. So, just to see what happened, I reconnected the OE horn at the same time, and - lo - it worked. I've no idea why what I've done here works fine yet other people can't even get a relay to be driven by the horn circuit. Maybe newer bikes (mine's a week old) have different tolerances in the power supplies ... ?

See pictures 2 and 3 for details of how I mounted the new horn. Basically I used a right angled bracket mounted on the same stud that the OE horn is on, but with the longer part of the bracket vertical rather than hroizontal. With the new horn central on the bike, it's a good inch away from the forks whatever the position of the steering.

For anyone wanting to try this, the horn I used was a "SEGER 12v low tone" - I measured its resistance at about 20 ohms. I'm happy to report it's painfully loud and wonderfully cacophonous (is that a word?).

Picture 1 - the wires



Picture 2 - new horn mounting viewed from the front



Picure 3 - new horn mounting view from the side

Mouse, thank you so much for taking the time to write this up and post those pictures! I intend to augment the lousy stock horn too.



I have one concern about your installation: If you look at the fork legs in picture 2, you will see a ring of drt/dust way up high on the lefthand chrome part that shows how much the fork has compressed. Do you think that was full compression? The concern is that if your fender is closer to the bottom of the horn than the distance from the top of the slider to that dirt ring, your fender and horn will strike each other upon full suspension compression, which might cause some problems.

Please forgive me if you have this already worked out...

On some bikes that would be a problem but not on the GS. My new horn sticks out (oo er!) about an inch below the oil cooler, no way do the forks have enough travel for the mudguard to get close

This was a problem when I did a similar thing to my fazer though.

Just to follow up with more precise info.

The maximum possible fork travel is 7 inches (distance from fork seals to top bracket). But the distance from the seal to the dust mark on the fork leg is 5 inches. Pretty sure this is close to maximum travel as I "tested" the ABS on Sunday when a sheep ran out ...

The distance from oil cooler to front mudguard is 10 inches.

However, where I have mounted the new horn, it would be in more danger of striking the telelever ball joint than the mudguard, in the event of extreme fork compression. The bottom of the horn is 7 inches directly above the ball joint. However, the end of the telelever will move upwards in an arc as the suspension compresses, so this doesn't worry me unduly.

My one remaining concern is the brake line that goes down to the telelever arm. I'll check that out further and report back.

Bah, the extra horn did touch the brake line.

So at least I know now, that there seems to be no electrical problem, just the problem of where to put an extra horn. There's not much room at the front of the bike.