Last year I installed a very loud
Stebel Nautilus Truck Compact horn on my 650F, to replace the standard horn. I posted a
video of it on Youtube at the time.
Yesterday I got a new comment from someone on here asking for pictures & directions, so I tought it was a good idea to post those here instead of just emailing it to him
As this is a very loud horn with it's own compressor you can't just plug it in the connector for the original horn, it needs it's own lead from the battery. So, we first have to fix that:
Of course this needs it's own fuse (has to be bought seperately), so I added a fusebox to the cable, and located it next to the original fusebox:
Then lead that wire to the front of the bike where the horn is fitted, I had it follow the frame & original wiring :
As this thing needs quite a lot of power, more than the little horn-button on the handlebars can switch properly, it needs a relais. This is included with the horn, with instructions on how to connect it. The wire from the battery goes on one pin, the wire to the horn goes on the opposite pin. The 2 wires from the original horn go on the remaining pins. One last wire goes from the horn to the ground, I put it around a nearby framebolt with a wire-ring-thing (forgot to take picture of that). See the provided instructions for which pin on the relais is which exactly, this appears to be not the same for all the versions of the horn.
Mount the relais somewhere convenient, I used Tesa Powerstrips to 'glue' it under the black plastic surrounding the dasboard & headlight, together with the ballast for my Xenon:
The black plug near the blue wires is the original horn-plug.
Some tape was added to make it a bit more resistant to vibrations, and watertight. There are no pictures of the relais-pins itself, because I didn't feel like re-doing my McGyverstyle-waterprotection
I mounted the horn itself under the plastic part between the fairing and the tank:
The blue wire you can see on the lower left of the pic below is the ground wire, I mounted it with a ring-connector around the bolt that holds the metal cable-holder you can see next to it.
For this I drilled a hole in the plastic, and mounted the horn with the provided bolt & washer. Or maybe that washer wasn't provided and I just found it somewhere, I don't really remember
I still have to paint it black some day...
I removed the original horn as it it not needed anymore, but you can just leave it in place if you want to. I tried mounting the Stebel on the original horn-bracket, but it is too big. Because of the long supension-travel, you will crush the stebel when braking heavily or driving over a speedbump.
Here is the video of the installed horn on Youtube, and
here are larger versions of all the pictures.
I hope this is useful for some of you
(Yes, my bike is very dirty, and has some corrosion. It's done over 35.000 km already, I drove it though the winter, and I'm not very good with cleaning... )
) 
