There are several different ways to install the Stebel Nautilus air horn onto the CS. This page features a general quick overview and two installation options: One by Mr Beavin next to the voltage regulator and one by BSK in the stock location. Both installation instructions do not use any extra parts except wiring components.
Installation by MrBeavin
I installed a new Stebel Air Horn on the CS this weekend. The thing is seriously LOUD! Very Happy
I worked out this solution because I was too lazy to drive to Lowes or search my parts bin for some scrap aluminum to make a bracket.
I bought the horn and the wiring kit from Twisted Throttle. The instructions for the wiring kit were very straight forward and easy to follow so I won't go into all those particulars. The relay comes with the horn and it simply plugs into this wiring harness.
The wiring harness wires have all the connectors already and the wires are:
Red - Power from battery
Twisted Black/Blue - leads to the old OEM horn
Yellow - Power to the Air Horn
Single lone black wire - grd for the Air Horn
Remove the seat, left side body panel and the little body panel between the left and right side body panels (near the front of the seat).
Pull the battery out enough to get at the positive terminal and connect the red wire from the wiring harness. Put the battery back.
Zip tie the relay into any space near the battery where it'll stay dry.
Route the twisted black/blue wires around the air intake duct to the front of the bike.
Disconnect the electrical plug and remove the old OEM horn and the mounting plate that it is attached.
Note that the mounting plate is actually 3 "thinner" plates stacked together to form one piece. This is the key to the installation.
Cut some tape off to expose the wires of the OEM horn electrical plug. Snip off the plug leaving enough wire exposed to strip the ends of the them. These wires are used to connect the circuit from the horn button.
Connect the new wiring harness wires to the power and grd wires using the two little butt connectors that come with the wiring harness kit. OR, if you have some female spade connectors you can use them on the bike wires and it'll all plug right up. Tape it up for extra protection.
Plug the yellow wire into the Air Horn and temporarily grd the black wire. Turn on the battery, put in ear plugs, and test the horn by pushing the red horn button. It should make your ears ring.
If everything checks out you can proceed. If not, double check all the connections.
Now, with 2 of the 3 OEM horn mounting plates go to the right front of the bike.
The engine support frame uses 2 M8x60 Hex Bolts to connect to the bike frame. These are located right below the oil tank lines. Only remove 1 of the bolts at a time.
After you remove the bolt you should have 1 bolt, 1 nut, and 2 washers in your hand.
Take 1 of the OEM horn mounting plates and line it up with the hole in the engine support frame where you removed the bolt. It should be pointing forward towards the tire. This is going to replace 1 of your washers. Put the bolt back in and tighten the nut/washer on the other side until its snug. Now bend the mounting plate 90 degrees until its pointing at you (to the right).
Loosen the nut and rotate (180 degrees) the mounting plate so the bend you just made in it is in the back and then torque the bolt down to specs.
Repeat the process with the next engine support frame bolt (M8x60).
You should have 2 washers left over.
Mount the Air Horn to the top mounting plate using the bolt/nut that came with it and your 2 left over washers.
Using zip ties, secure the bottom mounting plate to the Air Horn. There are no additional mounting points on the Air Horn so you need to wrap the zip tie around it and through the hole in the mounting plate.
Using any bolt on the engine, secure the black grd wire.
I had to start a new post to include the rest of the write up for some reason….
Plug the yellow power wire and the black grd wire into the Air Horn
Put in earplugs
If all is well replace the bodywork and seat
Enjoy your new deafeningly loud air horn in heavy traffic
Here is the final picture of the installation.
IMHO this is the best placement for the horn as it doesn't block the air flow to the radiator or VR. Of course, it is vulnerable to debris kicked up by the front wheel but everything is a trade-off. If I had a GS I wouldn't put it in this spot as mud and dirt would clog it up pretty quickly.
Installation by BSK
I installed the horn in the stock horn location which it fits perfectly into. Remove the stock horn and the stock horns bracket and the "keeper" that holds the stock horn straight. I used an old tire tubes section in between the new air horn and the triple clamp to reduce and vibration and noise that might occur with the installation in that spot.
I mounted my horn in the stock location and broke it when doing wheelies. There is not enough clearance between the horn and the front fender when forks compress. It cracked the horn housing and put a small dent in the front fender.