Still waiting for stars to get into proper seat-building/covering alignment here, looking for something to do to keep occupied in the meantime, thought I’d have another go at figuring out my horn problem yesterday. Writing about it today. May go for a pillow-seat ride tomorrow.
Started by checking out how horn actually works, recalling my high school physics class/electricity/how an electric bell works. Very similar. A hot wire goes to horn, another wire (still hot) goes from horn to horn button, which grounds when button is pushed, completing circuit. Current flowing through horn points energizes electromagnetic coil, pulls bar on top down which pushes down on end of points spring, opening points, de-energizing coil, bar pops back up, closing points, which allows current to flow again, energizes coil, and so on. Other end of bolt through top bar is attached to a metal diaphram that vibrates as bar bounces up and down as points open and close.
Looking at horn from side, I could see a little daylight between bar and end of points spring. When energized with battery charger, bar snapped down, but didn’t contact end of spring enough to open points, even with adjuster screw all the way out. So it just buzzed, stayed down, would have blown fuse if on bike. When I removed bar and leaf spring that holds it down, I discovered that point spring end had originally been covered with part of a bakelite insulator that goes back to points, but not now. This would have made it a little thicker than I found it.
To test my theory I put top bar, etc. back on, slipped a narrow strip of plastic from a cut up sample credit card between bar and spring end, tried it out. With a little adjustment, it honked. Aha!
So I took top bar back off, cut existing insulation on spring end back a bit with exacto knife, scraped off corrosion there as best I could. Mixed smallest batch of epoxy I could, and glued a tiny scrap of plastic where old insulator had evidently been. Took the opportunity to use points file to clean up points better than I’d been able to before. Reassembled after epoxy set up, and, with adjusting, it worked!
Adjusting horn: Turn adjusting screw all the way out. Stick straight screwdriver into adjusting screw, hook to battery charger, and turn screw down until a good solid honk is achieved. I turned screw past that to where it didn’t honk so good, then backed off to good honk again. Hold horn and screwdriver steady, it’s all gonna vibrate like crazy. Work fast, horn will be honking, dog(s) barking, significant other(s) and maybe neighbors complaining.
I have no idea how long this repair is going to last, but it seems like it ought to keep on working as long as epoxy holds. At least long enough to get it inspected, anyway. The honk turned into more of a beep when I got it mounted on the bike. It works, anyway.
Hopefully pix will help explain. Maybe this’ll help somebody with a horn problem sometime. – Lee
Fixing a horn
Fixing a horn
Lee, I'm still chuckling, visualising your pit-crew menagerie yapping and you trying to keep a hold on an electromechanical device with a life of its own! Bloody funny, in my head! I know this is an older post, but wanted to keep this question here as it's easier on the search and it pertains directly to the topic.
My horn does not seem to work when on the bike. It has never worked for me, but I am not the first owner. I may not be getting current to the horn as my tester has gone missing....Since I have no tester right now, I'd like to eliminate the horn as the problem. Can I just run 12v across the leads on the horn with my battery charger? The horn has two black wires coming out of it, does it matter which wire I use for the Red-side of the charger connection or the black-side? What do you think? Steve D CA78 - 3111XX - Frame
CA77E - 3161XX - Engine I don't think it's a good idea to use a battery charger this way. Depending on the charger, I believe you can do damage if you short the terminals. You would be better off just making a couple of jumper wires from the battery. Disconnect the horn and connect the horn wires to the battery jumper wires. Polarity might make a difference, although I doubt it. I have seen other horns with red and black wires. Make sure that neither of the horn wires are grounded to the frame to avoid shorting out the battery. Then just connect the horn to the battery and it should blow. If not, then you have something wrong with your horn. If it blows, you probably have either bad connections in the circuit or the horn button might not be making good contact.
You can get a cheap Digital Multimeter at Harbor Freight. For about 20 bucks you can get a really nice one there complete with a shock absorbing rubber case. regards, Rob
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