How to: Fit a Stebel Nautilus compact airhorn to an 07/08 4C8 R1 - Yamaha R1 Forum: YZF-R1 Forums
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post #1 of 1 (permalink) Old 12-05-2012, 04:53 AM Thread Starter
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Join Date: Mar 2008
Location: East Of England United Kingdom
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How to: Fit a Stebel Nautilus compact air horn to an 07/08 4C8 R1

I made this 'How to' on my own website in the UK, so thought I'd share it here as I had a request to do so.

I have fitted one of these Stebel Nautilus compact twin air horns, as I was fed up with the Japanese Mickey Mouse one fitted on my R1, motorists couldn't hear me but they will now! I couldn't find any info on one of these fitted to an 07/08 R1, except on Youtube where there was a video of someones R1 who had apparently fitted the air horn part under the left fairing and the compressor behind the dash, but I wanted the air horn mounted to the front end of the bike.

This twin air horn is REALLY loud, but legal, and I managed to fit it to my 2007 R1 without too many problems, but I had to split the twin air horn from the compressor to do it. I fitted the relay under the rear passenger seat, the compressor under the petrol tank, and the air horn behind the dash hidden by the double bubble screen. The instructions will be the same for the 08 R1 too, as well as many other sports bikes I would have thought, but check fitment positions first!

I had to buy the plastic piping, connectors and wiring for the installation as the twin air horn only came with a relay, the air horn draws around 18 Amps of current so you need beefy wire and connectors for the wiring up of the airhorn, but no such problem when running off the old horn switch connections to the relay as this already taken care of by having its own relay.

Materials and special tools needed:

27 Amp inline fuse holder with a 20 Amp blade fuse.

27 Amp wire for connection to the horn from the relay, horn to earth and inline fuse holder from battery to relay.

35 Amp insulated spade connectors for the air horn side of the wiring. Plus two 35 Amp ring connector for earth from the compressor, and from the inline fuse holder to the battery.

10 Amp wire for connection to the standard horn connections to the relay.

15 Amp insulated spade connectors for standard horn connections to relay.

Heat shrink tubing, cable ties, a metre or so of 1/4" bore plastic tubing, and a combined spade connector crimper and wire stripping tool.


The first thing to do was look for a suitable location to mount the Stebel Nautilus twin air horn plus the relay. Due to the complete lack of available space on the R1 due to its compact design it wasn't possible to mount it as one unit in a decent location. I worked out I had to seperate the compressor from the air horn then cut off part of the compressor's plastic housing to allow fitment of the air horn only behind the dash in the front fairing, the compressor went under the tank, and the relay under the passenger seat. This way all parts were kept hidden away from the elements.

Having worked out the location of the parts, the first thing I did was to disconnect the earth lead from the battery. No wiring was connected at the relay end until it had all been cable tied in, then the wire was trimmed to suit length wise and connected to the relay.

The first fitment was the heavy duty 35A inline fuse holder that was connected to the battery using a 35A ring spade connector, the blade fuse was fitted after completing the whole of the installation. The lead needed extending which was achieved by using a length of 35A cable to the inline fuse wire connected by 35A male and female fully insulated spade connectors, then covering with heat shrink tubing to be safe, this lead runs up to the relay under the seat.

The relay positioned under the passenger seat unit tucked out of the way.

Next I disconnected the old horn connections and run two 15A cables following the wiring loom to the relay under the back seat, and connected the wiring to the old horn connections using 15A insulated male spade connectors, I also wrapped them in insulation tape to make sure they were sealed from moisture.

Next came the fitment of the compressor which was mounted under the tank, I didn't need to remove the tank when fitting, propping it up with a piece of wood worked just fine. The two wiring connections were made first using 27A wire and two 35A insulated female spade connectors and covered in shrink tubing, again to be safe! One lead runs to the relay, and the other to the earth point under the tank which was connected and fitted using a 35A ring connector.

The compressor was then fitted in place and cable tied to the air filter breather pipe cover which also acts as a rubber mounting for the compressor. You have to make sure the compressor air intake faces outwards to keep the airflow free, and make sure no pipes under the tank get kinked or caught when refitting the tank.

The last thing to fit is the actual air horn itself, there is no wiring involved and the only connection needed is from the compressor to the air horn using a length of 1/4" bore plastic tubing. After cutting the plastic air horn to compressor mounting as close as I could without damaging the air horn itself, I found the air horn fitted perfectly behind the instrument panel under the main clock wiring loom and sat on the the side connectors light wiring, with just the need to remove the double bubble screen to fit. The only minor hitch was that the earth wire that connects to the back of the instrument panel cover needed extending, this wasn't a problem and just involved cutting the original earth connector off and soldering an extension of 15A wire to it, then covering with shrink tubing and crimping a 15A ring connector on and connecting up.

The 1/4" bore plastic tubing was carefuly threaded through the frame and connected to the compressor first, and then cable tied back from the tank to the instrument cluster following the lighting wiring loom, being careful to make sure that it doesn't catch or chafe on anything when turning the steering. With the air horn in place the tubing was cut to length and the end tapered with a craft knife which allows for a tight push fit into the air horn's air intake hole. A couple of cable ties were used to hold the twin air horn in place with the twin air horn pointing down as recommended in the instructions.

All that's left now is to cable tie the wiring, and connect the wiring to the relay which is clearly shown in the Stebel air horn instructions. When cable tying follow the looms where possible, but make sure the wiring stays away from heat sources such as the engine, or anywhere that chafing could occur. I used two 35A female insulated spade connectors to connect the battery inline fuse connector and compressor positive + leads to the relay, and two 15A insulated female spade connectors from the original horn wiring to the relay. Then covered them all in insulation tape to be safe yet again.

Finishing off I placed a 20A blade fuse into the inline fuse holder and reconnected the negative battery lead and reset the clock. Now comes the best bit the test to see if it works after turning the ignition on, just don't do it at home if you have any miserable neighbours, or feel free if you want to wind them up!! If all works as it should replace the body work you have removed and it's job done.


I really rate these Stebel Nautilus twin air horns and will give them a full 10/10. You can't fault them for loudness, and could save your bacon too when confronted by some bone head on four wheels who is half alseep and needs a nudge to wake up, I highly recommend them................ get a set!

............................. Please feel free to link to this review thread to otherwebsites, BUT remember that this review is the intellectual property of boz, please do not copy or reproduce the text or pictures in part, or whole on other sites without the express permission of it's copyright owner, or action WILL be taken. You only have to ask!!

Last edited by BozUK; 12-05-2012 at 07:26 AM.
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