Topic: Not your average horn thread!

[eideteker]

I've looked through the horn threads and couldn't find my situation...

The stock horn died ('73 CB500, per sig) and I replaced it with a cheap eBay knockoff.  It works, but only when over ~2500 RPM even if the headlight is off.  I have ~12VDC at the battery with nothing on, and ~14.5VDC at the battery when the revs are high enough to charge.  This is only a problem once a year when I get the bike inspected and the inspector raises an eyebrow at me and puts a sticker on it anyway, but I'd still like to get it working properly - when riding it works fine.

Any ideas?  I don't know the amp draw of the new horn, could this be the issue?  I thought when I put my clubman bars on and cleaned up/greased the bullet connectors in the bucket it would improve, but that was not the case.  The chassis ground at the battery negative cable is as clean as can be (as is the one at the ear inside the bucket), is there another ground I should be looking for?

[bollingball]

Not sure about the 500. But do you have one wire or two on the horn.It should have power at the horn and the ground is made when the button is pushed Did you clean the button when you changed the bars? Also you should have 12.6vdc with a good battery how old is it is the fluid level good? Charge it up good if it gets to 12.6 or higher then try the horn. Check where your coils mount for another ground 750s have one there but not sure about the 500. You say it works at 2500 rpms check your voltage at that speed.Then we will know what it takes to trigger the horn.

                Ken

[Greggo]

and I replaced it with a cheap eBay knockoff. 

I think we found yer problem.  The horn that died, did it work well before crapping out?

[KingCustomCycles.com]

Try hooking the horn direct to the battery with some jumper wires.  That will show if it is the horn or the bike wiring.

[bollingball]

Doesn't it allways work before it craps out

[wingman1946]

Have you installed an on/off switch on your headlight?  I did and when I have the headlight turned off the horn will not work. I used the headlight ground to place the on/off so maybe the horn shares the same ground wire.

[KingCustomCycles.com]

Yes, in order for something to "crap out" I would think it would, at one time, have had to work.  This would be in contrast to the "piece of crap" which may imply that it never worked. It is all a crap shoot with these Hondas anyway.

[eideteker]

bollingball: No, I didn't clean the button when I had the bars/controls off. 

Greggo: No, well kind of?  The stock horn did the same thing (requires revs to honk) plus it sounded like a dying goose.

KingCustom: I will jumper it to the battery to see if it goes at 12VDC, good idea and I hadn't thought of that.

wingman1946: Only on/off switch for the headlight is the one that was installed in Japan back in late '72.