July 26th, 2025
You would think that a horn has GOT to be the simplest possible component of a motorcycle, except perhaps after the tail light. Here’s a diagram of an electric horn:
Note that the contact points are touching each other in the diagram on the left. This means that, when the switch is closed, electricity flows through the coil. The coil becomes magnetic from the electrical current, and so pulls the armature towards it, as shown on the right. The armature pushes the left contact point away from the right contact point, which breaks the circuit, stopping current flow through the coil. Without any current, the coil demagnetizes, releasing the armature, which moves away from the coil, permitting the points to contact each other again, which starts the whole process all over again. This happens over and over and over, rapidly, so the armature moves in and out rapidly. In so doing, it pushes and pulls the diaphragm in and out, which makes a sound. The faster the cycle takes place, the higher the note made by the horn. Simple enough?
Well, that’s not the case. I cleaned up the horn on my bike and tested it. Nothing happened. “No problem!” I laughed. I have two other horns in the parts I bought earlier, and a third spare on the old CA160. So I tried Horn #2. It didn’t work. So I tried Horn #3. It didn’t work. Horn #4 wasn’t original.
Now what? I scoured the web and found somebody who wrote:
I bought one for my CB160 very cheap because although it was fairly clean looking, it was inoperable when the seller tried to test it, I think I got it for under $20 shipped.
I gave it a good internal cleaning and lubed the pivot points and it came back to life quite well in under an hour. No need to spend hundreds of dollars on the only working horn on ebay, just like the rest of the bike this horn was built to last forever.
I decided to open up one of the horns to see how they worked. Here’s what I found inside:
I decided to open up one of the horns to see how they worked. Here’s what I found inside:
You can see the two contact points. The lower one is on the reddish-brown platform, facing up. The upper one is on the bent steel piece just above the lower point. If you look closely, you can see that the two contact points are touching. This is as it should be.