Stebel Nautilus horn - split install

Table of Contents

This photo installation guide has been very kindly provided by Tim Carroll:
Copyright Tim Carroll & Liam Venter 2011.

The Stebel Nautilis Compact horn is excelent, loud and small but it is sometimes hard to find enough space. While it will fit straight on many bikes, it can be obtrusive and ugly [when you are not able to tuck it behind a fairing, etc].

There are two versions of the Stebel Nautilis Compact horns the 'Classic' and the '2nd Generation'. The 2nd Generation ones have a more weather proof compressor and are ideal for mounting on faired bikes where you can hide them away behind a fairing.

However with the Classic version of these horns it is possible to easily split the compressor component from the trumpet and fit them separately with an air tube between. This allows many more options as to where you mount the compressor and the trumpet on the bike. With the classic you can mount the compressor  out of the way (and out of the weather) under the seat and mount the trumpet somewhere else on the bike.

This is how I did it on my 2010 MTS1200S.
 

[FastBikeGear note: If you are going to split the units make sure you order the older 'classic' Nautilus not the newer more weather tight '2nd generation' units which have a weather shield fitted which makes the much harder to split. Both can be viewed on this page www.stebel.co.nz The good news is the older classic is cheaper than the newer unit. ]

Step 1.
Split the compressor from the resonators it is held on by three things. A tab near the air outlet from the compressor, some weak glue on the body of the compressor and a ridge on the air intake tube. Firstly deal with the tab near the air outlet from the compressor. You can just break off the tab cage as you won’t be needing it.

Step 2. There is a small amount of weak glue holding the compressor onto the plastic. Just slide a flat screwdriver under the plastic to break the glue.

Step 3.
The black plastic component has a built in air intake tube that has a ridge that pits into the compressor inlet. Just lever the plastic off the compressor to lever this ridge out of the compressor air intake hole and the plastic component should slide off the compressor. Note the compressor air outlet has a small o-ring seal.

Step 4: Separate components: At this poiint you might want to make each unit as compact as possible so I used a Dremel tool to slice the compressor wraps off the plastic trumpet and also cut the air intake section out. I left enough plastic to drill and mount a bracket. I also cut off the mounting point off the compressor body as I don’t need that either (see FastBikeGear note below before doing this). I think it best to try to keep the air intake section as it is small and should help to stop water getting directly into the compressor. I glued this back onto the compressor using contact cement and rubber banded it on and left it overnight.

[FastBikeGear comment: A great way to mount the compressor to a round frame tube is to use a Munzing clamp (see image below). These typically cost $5-$10 and come in a range of sizes that clamp on to different size pipes.. You can attach a mullins clamp around a frame tube and then bolt the compressor to the clamp using the stander mounting point on the compressor. If you are going to do this DO NOT cut the mounting point off the compressor body]

A brass air line fitting can be screwed directly into the air intake hole in the resonator. It fits perfectly and you don’t even need to tap it out. I used a thin smear of silicone to make sure it seals. NOTE, don’t screw it all the way in or it can block the air flow into the resonator. Screw it in about ¾ of the available thread. Other plastic options are available but this is what I had lying around.

[FastBikeGear comment: Use a brass fitting with a 5/16" hose nipple to 1/8" pipe thread or just get a double ended fuel connector fitting from Repco and silicon it into the hole in the trumpet - being careful that the silicon doesn't block air flow of course!]

I made up a simple bracket for the resonator out of stainless from a boating shop. This is called a chain plate but you can use anything. This was bolted to the horn resonator with 2 stainless bolts, washers with nyloc nuts. I put poly plastic washers in between the bracket and the horn to add a little flexibility.

I think it best to try to keep the air intake section as it is small and should help to stop water getting directly into the compressor. I glued this back onto the compressor using contact cement and rubber banded it on and left it overnight.

I found the compressor fits well in the Right side panel of the MTS but I thought it better to pad it out with neoprene. I had a drink cooler handy (Australians call this a stubbie holder) that I sliced up and cut to sive and glued on with contact cement and left overnight to dry. I then sprayed it black and it looks better in reality than the pictures. In the photos I have zip tied it ontoi the frame rail but I will make up a better bracket.

[FastBikeGear comment: A great way to mount the compressor to a round frame tube is to use a mullins clamp. Which looks like a hose clamp with a nut attached. You can attach a mullins clamp around a frame tube and then bolt the compressor to the clamp using the stander mounting point on the compressor.]

I removed the standard horn. Note that this horn uses its mount for the vibration adjustment, so you have to loosen the nut and then wind the centre bolt like section out to remove it. I simply bolted the new horn section to the standard bracket. As the hole in the bracket is large I put a grommet in the hole and sandwiched this with large stainless washers. This again adds a little flexibility and I think this is a good thing for a horn.

I twisted the bracket slightly before fitting the plastic trumpet to the bike to align the horn with the bike, and allow it to fit neatly under the carbon shroud and also point the sound outlets out and down to maximise sound output and minimise water ingress.

I used 8mm silicone surgical tubing and covered it with a black wiring cover I had lying around to make it less conspicuous where it is visible. I added heat shrunk the ends. As the compressor had a conical air outlet with no barbs I glued ...this tube on and added a small zip tie. I routed this tubing along the frame rails.

[FastBikeGear comment: We recommend the use of reinforced fuel hose between the compressor and trumpet as it is less likely to get kinked. If it gets kinked the compressor has a lot more work to do to try and blow air through it and a kinked hose can cause blown fuses and overheated/damaged compressor. The other advantage of reinforced fuel hose is that it you can get it in black.

Finished!