Horn Electrical Problem

Snortin Vache said:

Could someone explain to me what’s going on and what the correct way to hook up this horn is?

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Snortin Vache said:

Hello all,

After rewiring my bike but leaving the horn disconnected because of its buried location, I finally took the rear fender off and got at it.

Here’s what I’m experiencing: there are four male spades/terminals on my horn, a pair on top, and a pair on bottom. I thought that the proper way to wire it was to connect one wire to the top, and one to the bottom. Right now, if I jumper the negative terminal of the battery to one of the leads (not sure if it’s top or bottom as it is reentombed ) the horn beeps. If I jumper the negative terminal to the other lead I have connected to the horn, it heats up and I get smoke from the wires. I did all this testing after I had everything connected and I pressed the horn bottom and got nothing but what sounded like the horn wanting to sound.

Could someone explain to me what’s going on and what the correct way to hook up this horn is?

Thank you!

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concours said:

Did you bench test the horn?

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Snortin Vache said:

I do recall that it only seemed to work with one spade on the top, and one on the bottom.

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Snortin Vache said:

I did bench test the horn, and it beeped. I didn’t do every configuration of terminals, but I do recall that it only seemed to work with one spade on the top, and one on the bottom.

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Snortin Vache said:

Okay, I am not understanding what is going on still. What could be happening if my two leads, one purple black wire to the top pair of terminals, and one red wire to the bottom pair of terminals, and a horn that before reinstallation seemed to work, doesn’t work. The handlebar switch I am quite confident works, as is the wiring to the switch.

When I unplugged the two wires (I have two short wires with female spades to the horn and bullets on the other end of them to allow me to unplug and plug them from the harness by the oil tank instead of buried under the battery tray), I tested them with alligator clips to the battery. The purple black wire jumpered to the negative causes the wires to melt. The red wire jumpered to the negative causes the horn to sound.

I am only asking because I don’t want to take the fender off again, but I think I will have to anyway.

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Snortin Vache said:

Okay, I am not understanding what is going on still. What could be happening if my two leads, one purple black wire to the top pair of terminals, and one red wire to the bottom pair of terminals, and a horn that before reinstallation seemed to work, doesn’t work. The handlebar switch I am quite confident works, as is the wiring to the switch.

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Torontonian said:

You may have to go in there again to remove it . Fit a louder modern lighter horn , outboard on the bike , using a relay .. The challenge is finding a mounting place that is not ugly .

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marshg246 said:

I use these: https://a.co/d/5mJDQKZ

You can install in the normal spot but I like two, one on each side at the top rear of the Z-Plates or other more-or-less hidden spots. They are very small, much louder, and draw much less current. A Lucas RA6 relay is fine, but not really needed with these horns. The point of the relay is to have the horn button to "see" a small current and the relay to provide a direct path from the battery to the horn(s). When using two of the old horns like on a Trident, the relay is an absolute requirement.

Most don't know that the original horns draw about the same amount of power as the rest of the bike when working properly and are nearly a short circuit when not working properly. Many harnesses show melted or at least overheated wires for the horn! The horn consists of an electromagnet and points connected to the diaphragm. When the points are closed the magnet is engaged and the coil is simply a coil of wire (high current). As soon as the magnet pulls the diaphragm, the points open breaking the circuit and this happens at the frequence of the horn. Adjust it too tight and hold the horn button and your wires will melt! Let the points get corroded and they will sap too much current for the diaphragm to pull and the points to open - again, hold the button too long and your wires melt! Any poor connection along the path to the horn can result in the same thing.

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marshg246 said:

I use these: https://a.co/d/5mJDQKZ

You can install in the normal spot but I like two, one on each side at the top rear of the Z-Plates or other more-or-less hidden spots. They are very small, much louder, and draw much less current. A Lucas RA6 relay is fine, but not really needed with these horns. The point of the relay is to have the horn button to "see" a small current and the relay to provide a direct path from the battery to the horn(s). When using two of the old horns like on a Trident, the relay is an absolute requirement.

Most don't know that the original horns draw about the same amount of power as the rest of the bike when working properly and are nearly a short circuit when not working properly. Many harnesses show melted or at least overheated wires for the horn! The horn consists of an electromagnet and points connected to the diaphragm. When the points are closed the magnet is engaged and the coil is simply a coil of wire (high current). As soon as the magnet pulls the diaphragm, the points open breaking the circuit and this happens at the frequence of the horn. Adjust it too tight and hold the horn button and your wires will melt! Let the points get corroded and they will sap too much current for the diaphragm to pull and the points to open - again, hold the button too long and your wires melt! Any poor connection along the path to the horn can result in the same thing.

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Sergio said:

Those crazy Lucas horns can leave you roadside after an agressive use against a careless car driver!!!

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Sergio said:

Those crazy Lucas horns can leave you roadside after an agressive use against a careless car driver!!!

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