Boys and Girls,
I've been hanging around this site for long enough to start feeling guilty about finally getting something back to the community.
So here is my contribution: a detailed description of my Stebel nautilus horn install (with pictures)
Stebel Nautilus is a compact air-horn with a claimed loudness of 139dB. When you read a fine print on the box, you will find out that the 139dB value is measured at 4 inches away from the horn's "mouth". I dare you to try if it's true... you'd be deaf if you did. From a more convincing distance of 6ft, the horn is rated at 115dB (If I remember correctly) which is a little bit less impressive, but stil VERY, VERY loud.
Comparing the Stebel to the stock horn is quite revealing. In fact I have opted not to remove or disconnect the stock horn while installing the Stebel. There were two reasons for that: firstly even though the Stebel has virtually no audible "delay", due to the way I installed it and do to it's "air-horn" nature it is actually a tiny bit "slower" than the stock horn.
So, you can easily compare the "before" and "after effect by lightly tapping on the horn button and /or pressing and holding it all the way. The weak annoying, stock "meep, meep" is instantly flooded by a blast of dual-tone air-horn goodness - ear-piercing and sure to keep cagers on their toes.
The second benefit of dual-horn setup is that it lets you modulate the output. For example: If you are in front of your girlfriend's house and you just want to let her know you're there and waiting, gently tap the button - the usual lame "meep-meep" will sound. After you've waited for 20 more minutes and you're starting to realize you gonna be late for the movie, press the button all the way. By then she'll know you guys are late for sure. And so will all the neighbors.
Another possible scenario may include a situation where it's necessary to differentiate from a friendly: "come on, move on, just a little bit more...I need to turn right and you're in my way" to "get the fuck out of my way you retard and watch where you're going next time!!!"
OK, after spending a fair bit of time trying to figure out the best way to do this and after looking at other people's pictorials and instructions I decided that due to the limited space available under the fairings on our scoot I will need to split the horn to allow for better flexibility. In other words, I couldn't find a good place to install it the way it is "out of the box"
Here is how it looks like after taking apart the compressor and the horn "halves". It is easily done, there are couple of clips that hold it together, it is not fastened in any other way.
Once the compressor is separated from the horn they need to be connected together using some sort of tube - I used a flexible clear hose from a hardware store. It has been secured on both ends by hose clamps, same as the ones used on the air-lines.
The horn "module" ends-up with a hole after separation, so there needs to be some adapter/connector fitted in place- I used a heater hose plastic connector form an automotive supply store. It is firmly pushed in place and glued using a pvc glue (used for plumbing jobs). Some fitting and finishing with fine sandpaper was necessary, also the clips that earlier secured the two pieces together were "shaven" using a cutting disc on my Dremel.
Sidenote: Dremel is indispensable for this and any other similar job. You can do without, but it is much easer if you got one. If you enjoy tweaking and fixing things, go get a Dremel tool NOW!
The Horn piece was left with some extra plastic after the compressor was removed, so that was promptly cut-of using.. you guessed it!... a Dremel!
I also drilled four holes at the corners of the remaining "bracket" - they are later used to fasten the horn to the mounting surface with some zipties.
The compressor part is fairly heavy and it vibrates when working, so it needs a bracket. There is a factory supplied hole to mount it using a supplied screw, but I couldn't find any place where to use the suggested setup. So I made a strap out of some aluminium, drilled a hole and affixed the compressor part to the existing ECU bracket using the existing screw. It is positioned at the left side, behind the legshield and it is tucked nicely just at the foot rest level.
Here is how it looks:
The clear hose is looped behind and under it - you will see how its attached to the horn part soon...
The horn part is actually pretty light and it doesn't need nearly as much bracing to stay put. I decided to mount it on the inside of the legshield, on the left hand side, above the compressor using zipties and ziptie "bases" that are supplied with two-sided VERY sticky tape. Once the inside of the legshield is cleaned with alcohol, the plastic bases and zipties secure the horn to the surface.
To prep the spot I placed some rubber foam tape on both ends where the horn rests against the legshield and used some high density foam in the middle to make the whole thing stable.
Here is how it looks before the horn is attached:
Here is a close-up of the horn attached with zipties:
And here is the placement on the inside of the legshield:
Finally, both pieces connected with the hose, before the legshield panel is up and mounted:
Once the "mechanical" install was finished, there was some electrical connections to be done. The kit I got came with all the wiring needed, including the fuse/fuse holder and the relay was included too.
There is a clear wiring diagram printed on the horn box and the wiring is pretty generic, so as long as you follow the directions you'll be fine. Couple of things: the diagram suggests that the horn button runs on the negative/ground line. In case of our scoot the button interrupts the positive/hot wire. That makes no difference in the way the diagram is followed though. Also, I decided to retain the original horn, so instead of cutting both negative and positive connectors I soldered a "new" positive connection to the existing "hot" gray wire and attached the ground wire straight to ground (actually I used the negative terminal on the battery)
Grey "positive" wire off the stock horn:
Here is the "piggybacked" new wire:
And here it is with the handsome black cap supplied with the original horn:
The relay can be mounted on the other side of the centre column, using the other screw of the ECU bracket. There is ample space in there and its easy to route all the cables neatly, including the ones that need to be connected directly to the battery.
Sidenote: Do not try to skip the relay and use only the existing wiring. The new horn draws 20AMP of power and when I press the button light dim and the voltage drops from 14.3 to just over 12. Should you "forget" the relay your button and a better part of wiring will smoke and you'll likely do lots of damage. Please also make sure that the fuse is there and it reads 20AMP.
I placed it such that it is easily accessible from behind the little VIN trap-door in the centre of the legshield, just below the hook.
This is where you could test it, make sure it all works, put the legshield fairing on and be done with it.
However, I figured that once I had it all apart I can do one more tweak, which is to make an opening where the horn's mouth was facing the front fender "liner". I suspect that the Stebel is loud enough to be OK without such opening, but I was too tempted not to try this.
Using an old cheap computer speaker box I have fabricated a cute little plastic grille to be used as the cover for the horn opening. To mount is I used a "gasket" cut out of the two sided sticky tape - I got plenty leftover after mounting my helmet anti-fog lense:
Then I traced the "gasket on the "fender" fairing with a silver sharpie (at the point where the horn would face after mounted:
Cut it out with my trusty Dremel:
After finishing the rough edges a bit, affix the double-side "gasket":
And finally attach the "grille" to the sticky "gasket". BTW, this stuff is VERY sticky. If you clean the surface with some alcohol and try to do a clean job, it will stay put FOREVER. Finished product from the inside:
And from the outside:
When the horn blasts, the sound is amplified by the front wheel fender cavity and it projects it forward. Resonating properties of the scooters body help too, so this sucker is VERY, VERY LOUD!
So this is it. It took me a good part of the day today, but trying to take decent pictures and doing things in particular order for this reason takes a bit of extra time, actually.
I found this to be a fun and easy install, but I had all the tools and supplies and I planned ahead.
Be very, very careful with metal clips using for fastening the panels together with the screws.
Few of them fell out during the job (including when I was putting everything together) and it took me ages fishing them out from the scooter's belly. I would suggest that you remove all the clips before it's too late and tighten them before re-attaching. You'll save yourself lots of grief!
At the end of the job I got one extra screw left (?!) and lost one of the clips. The hook in the centre of the legshield fairing is now held with a single screw instead of two... I need to go see my dealer, maybe they can spare me one...
BTW, the centre hook needs to be removed to detach the panel - there is a single hex-head screw holding it all in the centre, covered by the hook.
Here is the one last picture - it shows the horn tucked nicely behind the legshield, as seen peeking through the VIN trap-door:
OK, that's all. I hope you find it useful and Muchacho - maybe this can be used as a sticky.
Drive safe and let yourself be HEARD with your new Stebel Nautilus horn.
U P D A T E :
After riding the scoot in fairly heavy rain I came to a conclusion that the horn "grill" opening was not a good idea. There is really not that much water getting in, but I'm concerned with the amount of mud/sand/fine gravel and other debris that makes it way into the opening.
Therefore I advise not to follow my example and leave the fender enclosed. If you decide to follow my installation procedure, please skip the "grill" part.
I will be covering the hole shortly.