How motorcycle horns work and how to repair them

Why did we believe this? Obviously, a motorcycle doesn't need a horn to function, even though the "rule" proved true more often than not. The horn was a proxy for overall mechanical condition, because it takes a lot to kill a good horn. Same goes for motorcycles . See where this is going?

If a motorcycle had been well-maintained and stored away from the elements by its previous owners, the horn would always beep encouragingly, and the rest of the restoration would be fine. But if the bike had been left outside, neglected, or flogged within an inch of its life, only to end up in our hands for a suspiciously low price, the lack of a horn meant sleepless nights to come. YMMV.

I won't get into the "noisy pipes save lives" conversation today, but make sure your motorcycle horn works so you can signal other road users as quickly as possible. Horns can definitely save lives if used (and listened to) correctly. They're also great for non-emergency signaling, so let's take a look at how they work, why they stop working, and how to fix or improve them.

How motorcycle horns work

The first motorcycle horns were just repurposed motorcycle horns , push-button bulb and all. Look at the horn button icon on your bike, and it might be a small trumpet. Klaxon-style horns (awoooga!) came later, in both manual and electric versions. At the heart of the Klaxon is a spring-steel diaphragm that vibrates to produce a startling sound. (The brand name Klaxon comes from Greek roots and roughly translates to "Scream!") You'll find similar diaphragms inside today's motorcycle horns, more than a hundred years later.

The cheapest, smallest and most common option today are round diaphragm horns. They are found on everything from scooters to heavy tourers, usually somewhere near the front of the bike. Inside these horns you will see a steel diaphragm above a small electromagnet. Pressing the horn button on the handlebars activates the electromagnet, which pulls on the diaphragm until it hits a series of contact points, breaking the electromagnet's pull on the steel and returning the diaphragm to its original process to begin the cycle again. The diaphragm continues to vibrate between these two positions to produce a constant tone. Simple, effective and very compact. If you've ever overhauled a fuel pump, you've probably seen the same electromagnet/points/diaphragm concept at work.

A variation of the basic diaphragm horn has a curled trumpet on the diaphragm. These are sometimes called snail horns. This arrangement typically costs a little more, but the horn helps direct and project the sound. They are not as metallic as the basic horns for my ears. As a general rule, the trumpet opening should face downwards when installed so that it does not collect water.

The biggest and baddest horns are the ones powered by miniature superchargers. They're bulky, but you won't appreciate their explosion until you've ridden with someone who has one. FWAAA! Get a horn if you're tired of drivers ignoring your weak horn. Some manufacturers combine the compressor and horn into one unit, while others split the two components for greater flexibility with mounting location. Note: Air horns almost always require a relay due to their higher amperage requirements.

Two horns are better than one

Most cars have a dual horn setup, while many motorcycles only have one, which is the main reason why motorcycle beeps sound like a toy or are weak compared to traffic. You will find two horns on some motorcycles, usually tourers and cruisers. A two-tone beep is supposedly easier to hear than ambient road noise, and manufacturers intentionally choose horns that complement each other for a louder, more premium sound.

If you wish, a second horn can be added to your motorcycle. Be sure to use a relay to protect the stock wiring if you choose this route, as the amperage involved can exceed the limits of the stock wiring. Complete double horn kits are also available for some models. Alternatively, you can upgrade your existing horn with an aftermarket replacement from Denali, Wolo, or Stebel, to name a few popular brands.

Troubleshooting your motorcycle horn

Non-working horns are easy to fix. Start with the horn fuse if your bike has one. Blown fuses often indicate faulty wiring, so check around for damaged insulation, frayed connections, and other basic signs of electrical problems. Next, test the horn itself. Remove the horn and try connecting it to a fully charged battery or a power supply. Try to keep track of the polarity when testing, but if you mix up the wires, your horn probably won't work. Still no beep? Skip to the repair section below.

If the horn sounds OK on the bike but didn't work when it was on , your problem is likely a wiring issue, a bad horn relay (if equipped), or a faulty button (assuming you've already checked the fuse). Grab your multimeter or build a simple test light to troubleshoot the problem. Find a wiring diagram and take your time.

How to adjust and repair motorcycle horns

Most people simply toss the broken antlers and buy new ones. Nothing bad, especially for the money. A generic replacement costs €10 to €15; ponies up to €20 to €50 for an upgraded model with a louder blast. So why bother fixing or repairing?

• Sometimes all it takes is a little adjustment.
• Replacements may be difficult to find for vintage/antique models.
• Taking things apart to learn how it works is fun.

Adjusting a motorcycle horn couldn't be easier. Find the adjustment bolt (or nut), usually on the back of the horn or in the center of the diaphragm. This adjusts the distance between the contact points on the inside, which can be disrupted by dirt, corrosion or wear over time. Attach the horn to the battery and adjust the gap until it beeps normally.

If the horn still doesn't work, it's time for disassembly. Look for screws, rivets, or a bent steel ring around the outside edge, then unscrew, drill, or pry the pieces apart. Don't forget the orientation of each component. And don't bend your diaphragm! Clean the innards thoroughly and check those contact points for oxidation. If necessary, lightly brush the contacts with sandpaper, then reassemble and test.

True, many motorcycle horns are decidedly weak from the factory. Don't let disappointing performance discourage you. Now you know the basics of keeping your horn in working condition or announcing your presence to everyone within earshot with a few simple upgrades. Just make sure the horn button does something.