Introduction: DIY - Motorcycle Air Horn Install Upgrade - 2017 Kawasaki Ninja 650 / Z650

About: Just a guy who doesn't know when to quit, and is constantly in search of a solution to a problem that doesn't exist yet.

Difficulty: Intermediate
Tool Requirements: Intermediate
Time: A weekend project
Cost: 40$ Approx.

I'm not sure why, but I've always been a fan of loud horns. And if you've clicked, I'm guessing you also have the same guilty vice. So when I passed on from my beloved 2015 Kawasaki Ninja 300 ABS (with it's Hella Supertones) to a new 2017 Kawasaki Ninja 650 ABS, you can be sure an upgraded horn was somewhere on the To Do list. There's nothing like scaring the bejeezus out of someone trying to merge in to you with a 139db horn, is there?

To be honest, I was perfectly happy with my Hella's. But it was annoying to have two separate horns to install and wire. This time I was curious about going with a pneumatic horn like the Stebel Nautilus, as opposed to your typical piezoelectric horn. Hopefully it would be louder, too. While I had my doubts, eventually I was able to find a viable spot and mounting solution for the horn, and here I'm going to go over the process should it make the life easier of anyone else looking to upgrade.

While this DIY is made for the 2017 Kawasaki Ninja 650, it's a great piece of inspiration for anyone looking to install a Stebel Nautilus Air Horn on any other sportbike, motorcycle or vehicle. With some improvisation, of course. This guide might might be updated over time. To see the latest version, click here.


Working on any vehicle can be risky to both yourself and the vehicle. No warranties or guaranties, explicit or implicit, are made or implied regarding the compatibility, suitability or effect on functionality, safety or any current warranties. All modifications should be made within the reader's capability and under their own exclusive responsibility.

A bit of motivation to keep making Instructables always helps. I'm a participant in the Amazon Services LLC Associates Program as well as eBay Partner Network, affiliate advertising programs designed to provide a means for creators to earn fees by linking to their sites, at no extra cost whatsoever to you.

Step 1: What You'll Need

The following list is mainly so you can make sure you have everything available before starting the project. Items in parenthesis mean useful, but optional. I expect most people to already have most tools and supplies in their garage. Some other typical tools are also needed (like ratchets or wrenches).

Main Parts



Step 2: Remove the Fairings

All the wiring you will need to access is pretty much on the left side of the bike. If you are thinking about taking on this project, you probably know everything you need to know about how to remove all the fairings off this bike. Unless you have specific questions (direct them to the comments below), I'll skip over this part. Removing the tank will also be just about necessary (which is easily done).

Pro tip: Mark your chain with a Permanent Oil Pen to make oiling your chain a lot easier (see picture). That way you know where you started, and where to end.

Step 3: Remove the Left Engine Mount Spacer

It quickly became obvious that there is very, very little space to mount anything, let alone a large aftermarket horn on this bike. I came to the conclusion that the only viable place to install it would be attached next to the left engine mount spacer, leaving the horn next to the exhaust pipes. Though not ideal due to that area being pretty hot, it was the only choice.

To install it, you'll need to slightly shorten the engine mount spacer, and then make some minor modifications to a steel shelf bracket to adapt it to the horn.

The first step is to use a 14mm socket to remove the left engine mount bolt. I personally had some OES Carbon Fiber Frame Sliders installed, which goes mounted in the same location. Once you've removed the bolt, remove the nut installed behind the engine mount, and remove the spacer (which is simply held in place under friction and light tension). To see more info on how to remove the engine mount spacer, click here.

Step 4: Shorten the Spacer

The engine mount spacer on the left side originally measures 1.575 Inches in length. The Shelf Bracket I was using measured 132 mils (0.132"). Measure yours to see what the correct thickness to subtract in your case is. You want to shortened spacer + bracket to measure the same as the original spacer (1.575").

I shortened the spacer to 1.443 inches with a milling machine. If you don't have one available then you could use an angle grinder with a metal grinding wheel or even a bench grinder. It would be important to make sure the exact length is achieved, and that the edge is square.

The good news is that if your feeling uneasy about screwing up the original spacer, replacements are available online relatively cheaply. It's part "COLLAR, 10.5X26X40" and part number 92152-2230. And as time passes and more used replacements are available, the price will only go down. If that wasn't the case I probably wouldn't have dared to modify the original spacer.

After shortening the spacer break or bevel the sharp edge with a bench grinder.

Step 5: Recoat the Spacer

After I measured the spacer with a digital caliper to make sure the length was correct (1.443 inches in my case), I sanded the edge to remove the machining marks and leave it smooth. In the pictures you can see that I did the sanding on top of a glass pane to make sure that the edge was perfectly flat. I used a few different pieces of sandpaper, between 200 and 1000 grit.

I hate rust and corrosion, so I always recoat any bare metal edges. In this case, so I wouldn't have to wait for paint to dry, I used some gun bluing to recoat the bare metal edge. Basically it's just an anodized-like coating which creates a durable layer of protective black rust. The product I used was Birchwood Casey Gun Super Blue. You just have to degrease the surface, make sure it's smooth (without major scratches or apprentice marks) and then roughen it with some steel wool. Apply the liquid with a Q tip, then wait 30 seconds and wash it off. Repeat two or three times until it has a strong black finish. The finish only looks best after applying a coating of oil to it since it slightly absorbs the oil in it's pores, helping to prevent rust.

Step 6: Cut the Bracket

We need a bracket to attach the horn to the bike. I used an Everbilt 10 in. x 8 in. Black Medium Duty Shelf Bracket, with a cost around 5$. I purchased it at Home Depot, where they had an assortment of shelf brackets. Your best bet is probably to go buy it in person where you can judge easier which would be suitable for you. I personally went with this one since the bracket's width was equal to the diameter of the engine mount spacer (around 1" diameter).

The first step is to cut the bracket to make it easier to handle. I used a Deep Cut Portable Band Saw, but if you don't have something like that on hand a pneumatic or electric reciprocating saw. Or simply a hacksaw. For now just shorten it roughly.

Step 7: Enlarge the Engine Mount Bolt Hole

If you're using the same bracket I'm using, the centered hole on the bracket suits us just perfectly. Drill it to 10mm, which is the diameter of the engine mount bolt.

Step 8: Mark the Bracket for Cutting

For a professional installation, we're going to want to mark the diameter of the frame mounting point against the bracket with a metal scribe. Simply trace the edge with the scribe.

Step 9: Trim the Bracket

Trim off the excess metal we just marked with the scribe, and then use a bench grinder to break up all the sharp edges.

Step 10: Test Fit the Bracket

At this point, you'll want to test fit the bracket for a small morale boost. It should look like this.

Step 11: Drill the Hole for the Horn Mounting Point

I ended up mounting the horn as close to the right angle as I could. It seemed the best position, and it would be the strongest position for the the bracket.

Just hold the bracket against the horns top mounting hole and mark it. Then drill. You'll want to drill the hole slightly too close to the horn. See the next step to understand why.

Step 12: Grind the Bracket and Test Fit It on the Horn

To lock the bracket in four dimensions (including rotation), we'll want to grind a slight curve in to the side of the bracket that matches against the curve of the silver cap on the horn. This way the bracket will be effectively locked in place despite being held in place by a single bolt.

We are also going to have to enlarge the top mounting hole on the horn's mounting point. For some reason it's smaller than the supplied bolt. Simply drill it in the same diameter as the bolt supplied with the horn, 8mm.

Step 13: Test Fit the Horn on the Bike

Test fit the horn, both to make sure we're on the right track, and for a morale boost. Also, I slightly bent the bracket inwards in a bench vise so that the horn would be slightly angled inwards for more clearance with the fairings. You'll probably know what I mean if you're following the project.

Step 14: Protect the Horn From the Heat

The horn is uncomfortably close to both the exhaust and the engine block. But it's as good as it's gonna get on a compact sportbike. I has some Lava Heatshield Mat leftover from the Cold Air Intake install on my car, so I just used that. Though if I would have purchased some adhesive heatshield specifically for this project, I would have probably ordered this: Thermo-Tec 13500 12" X 12" Adhesive Backed Heat Barrier. Mainly because it's cheaper and thicker, though it looks less aesthetically pleasing than the lava mat. In any case, you'll want to install some form of heat shield just to help protect the horn from the heat.

Take a look at the image to get an idea of how I applied the mat to the back and to the sides. I used a zip tie to secure it to the round portion. I used flush cutters to trim the loose fibers as well as make relief cuts. I also used 3M Adhesion Promoter, a product that I absolutely love for whenever I want to install adhesive products as permanently as possible. After installing everything in place how I wanted it, I applied some superglue to the edges just to secure them permanently.

Step 15: Some Info on Current Draw

Once this is done, it's time to start thinking about wiring.

When it comes to upgrading the horn, the typical question is "Do I really have to use a relay"? In this case, the obvious answer is yes.

I measured the current draw of the OEM piezoelectric horn to be 2.5 amps, whereas the Stebel Nautilus draws 19.25 Amps, almost 10 times more. So using a relay with a direct connection to the battery is a must when installing an upgraded horn like this.

Step 16: Connect the Relay Wiring at the Source

First of all, disconnect the battery terminals.

Personally, I hate having a bunch of different accessory wires to connect to the battery. In this case, the starter relay has the perfect location and wire gauge to simply hook up the relay's power wire there.

Since I like having a thick gauge wire going to the headlight area for any high power accessories, such as this horn (but also chargers or HID headlights), I used a 10 Gauge wire so I could trust that it could handle any current I'd ever want to throw at it. That wire can comfortably carry around 40 Amps continuously (and more) given it's short length. That way I know I'll never have to upgrade it, regardless of future additions to the circuit.

You'll also want to add a waterproof fuse holder here. I'd recommend going with either a 10 or 12 gauge mini fuse holder. Solder or crimp the connection (if soldering, strain relief is crucial) and apply adhesive heatshrink or electrical tape over it. You can also apply some liquid electrical tape before heatshrinking for the best water (read corrosion) protection.

Note: Whether to crimp or solder on vehicles is an almost dogmatic topic. If you aren't familiar, I'd recommend checking out the topic here. It can easily avoid you a lot of unnecessary troubleshooting in the future.

I personally like covering the wires in Expandable Braided Sleeving for a more professional look, as well as to protect the wiring from abrasion. 6 to 8mm sleeving is ideal for the main relay wire, with 2-6mm being better for the thinner wires. It's extremely cheap if you order it on Ebay from overseas.

Bring the wire you've connected there all the way to the front, to the left side of the headlight. Leave it long just in case you decide to add something to that circuit in the future.

Step 17: Remove the OEM Horn and Reroute the OEM Horn Wiring

You'll want to remove the OEM horn along with it's bracket, as well as reroute the wiring which powers the OEM horn to the relay which will be installed. The horn wires will be used to trigger the relay.

Step 18: Splice a Wire to the Main Power Wire

Splice a wire to the main power wire coming from the starter motor relay. I used 12 AWG Speaker Wiresince no more than that would be needed for the horn. Then I coated the connection with liquid electrical tape and heat shrinked over it.

Thread that wire through a gap in the braided sleeve and add some more adhesive marine heatshrink for a profesional look.

Finally, crimp on a spade connector to feed the relay.

Step 19: Make the Horn's Wiring Harness

I didn't take any pictures of the wiring harness, but it's pretty straightforward anyway. I used 12 AWG wiring. I sleeved it with the same braided sleeve as before. I attached female spade connectors on the horn side of the wire, and a spade connector plus a ring terminal on the bike side.

One wire will go to the relay powering the horn, and another to the bundle of grounds already on the bike. See the pictures for more info.

Note: One issue I didn't like about the Ninja 650 is that it uses an odd turn signal relay, which is expensive and for which there are no adjustable LED turn signal relays available (the ones that solve hyperflashing when LED turn signals are installed). To be able to use cheap adjustable LED turn signal relays you'll need an adapter. And as far as I know the only way to get the adapter is purchasing the Motodynamic LED Flasher Relay 12V 2-Prong w/ Connector. Just use the adapter and throw the included relay in your parts bin. That's how I was able to easily attach a generic adjustable LED Turn Signal relay (the orange relay pictured in the image). I feel like I'm more visible (read safer) when I'm able to adjust my turn signals to blink quickly (though not so much to be considered "hyperflashing"). With the adjustable relay I can set it exactly how I like it.

Step 20: Install and Wire the Relay

Install the relay and make the proper connections.

I chose a 12v 30a relay 5 pin. I like this relay in particular because it's compact, takes up to 30 Amps, is waterproof, has a diode for protection, and has 5 pins. I'll spare myself of telling you how to wire it since I can take for granted that this isn't your first rodeo if you've made it this far. Though if anyone needs any help, just mention it in the comments below and I'd be glad to update the DIY.

The perfect mounting location for this relay was in the empty spot between the Radiator Fan Relay and the Turn Signal Relay. Said and done.

Step 21: Test the Horn and Reinstall the Engine Mount Bolt

The horn should now be ready to test! Reconnect the battery terminals and give it a whirl.

Hopefully the horn worked on your first try. If not go back and take a look at the fuse (you'll need at least a 20 Amp fuse) and how you wired the relay. There isn't that much to go wrong so you'll solve it sooner rather than later.

Now would be the time to reinstall the Engine Mount Bolt. The correct torque for the Engine Mount bolt is 32 lb/ft, so use a torque wrench. Rotate the Horn Mounting Bracket to the angle you like most prior to torquing it down.

Step 22: Reinstall the Fairings and Enjoy!

Once you've tested the horn, the only thing left is to reinstall the fairings.

I sadly didn't record a before and after of the sound, but you can take my word for it that this is as loud as it gets on a sportbike. It also has that really nice 18 wheeler sound you only get with air horns. People sure look dumbfounded when they hear the horn and only see a small little sportbike next to them. To see an example of how the horn sounds on a prior model of this bike, click here.

Also, if you want to see what other upgrades I've done to my bike, check out my N650 mod list.

If you found this interesting, click the 'Follow' button up on the right to get notified of similar projects in the future, or check out my profile to see what other projects I've been up to — here are some you might like:

Step 23: Addendum - Will It Take the Heat?

To be honest, the horn is uncomfortably close to the exhaust pipes. There is only around a 1 inch gap between the horn and the exhaust. During movement there is no problem, but long idling or stop and go traffic could be a problem. However this is the best that could be done given the situation. I'd like to guess that the horn is designed to take high heat since the engine bay of any given car isn't precisely cool, so time will tell if the horn let's us down or not.

I considered wrapping the exhaust with DEI 010128 Titanium Exhaust Heat Wrap, which probably would have looked great, but given how controversial exhaust wrap is these days regarding accelerated corrosion, I decided against it. If I see the current horn start to show damage, I will absolutely wrap them.

But given that this horn only costs 25-30$, it wasn't a big risk to take anyway. If the horn fails, I'll replace it, wrap the exhaust and update. And if I don't update this, than it is safe to assume that there was no issue.

Audio Contest 2017

Participated in the
Audio Contest 2017