Repairing a 6V horn by Ross Kowalski
The CJ horn like most of the bikes components occasionally stops functioning. Unlike modern bikes, the components of the Chang can be repaired rather than replaced. My horn stopped beeping on the 6V and I needed an inspection sticker. I leave the bike outside so the horns points were likely corroded, and the same with the button.
Remove the six screws securing the grille and diaphragm to the horn body.
Separate the grille and gasket from the diaphragm.
Carefully remove the diaphragm and diaphram gasket from the horn body.
The points and adjustment screw. The horn works by an electromagnet pulling the diaphragm back, when pulled back the points break and the electromagnet turns off and the diaphragm moves forward, when the diaphragm moves forward the points close energizing the magnet and pulling the diaphragm back, and on and on. It all happens very quickly.
Here you can see the points closed. The little pointy corner of the bottom point plate is where the diaphragm touches.
Push the bottom point plate down to allow you to get some sand paper in there.
Clean the points with some 100 grit emery (which every respectable mechanic will tell you is a bad on several counts, anyway.)
Hold the points open and clean them with some contact cleaner or starting fluid or whatever. I also put a tiny dab of synthetic grease on the area of the bottom point plate where the diaphragm touches it.
Put a little automatic transmission fluid or anti-sieze compound on threads for next time. On to the horn button.
Open the horn button and sand the two bent brass tab contacts inside.
Sand the bottom of the button.
Sand the outside of the spring on the wide end where it makes contact with the button housing.
Sand the inside of the spring on the narrow end where it makes contact with the horn button, clean everything with starting fluid and reassemble.
With the ignition on, press the horn button and see if it makes a good loud beep. If it doesn't turn the adjusting screw until it does. Be careful to turn the screw a little one way, then a little the other, then a little more one way and then a little more the other and so on. If you turn it too far you could unscrew it on the inside and have to dissassemble the horn to make it right again.