Horn question - SF2

mik667

mik667

Senior member
Location
San Francisco, Ca
Hey gang - wondering if anyone has encountered a horn problem like mine or has any advice. My SF has the dual Fiamm horns  (they used to work). I've found recently that if i push my horn button there's no beep - but rather a sort of "plunk" sound that comes from each horn. At first i though it was the relay so  i put a new "modern" one in, and it still plunks plunks away when the horn button is pushed (if i put the lights on they noticeable dim with the original and new relay when the horn button is pushed - with a noticeable drop in voltage as measured at the battery. If i hold the horn button down for a length of time it will blow a fuse). I can unplug each horn, one at a time, and the remaining horn beeps quite happily - but again with both hooked up plunk plunk. I also took off the horn switch gear and made sure its got a clean surface where it contacts the handlebars. I figure it may be a dirty contact wire for the hot wire somewhere and cleaned all the contacts on the horns to no avail - anyone know which wire in the crazy connections is the horn hot wire or have any other suggestions to look at??

thanks as always!

mike
 
Sounds like you have too much voltage drop. Try cleaning all the connectors between battery and horn. Also check your battery voltage when you press the horn button. If you get excessive voltage depression (less than 10V) then your battery is probably on its last legs.
 
Mike, I don't know about the Fiamms but the round Voxbells always leak water in (they have a drain hole but it clogs up) and eventually they get so much corrosion inside them the metal diaphragm can't oscillate properly, similar symptoms to yours. First do what Cam suggests and check the voltage at various points (under some sort of load). If the battery seems OK and the voltage at the horns is somewhere near 12V, see if you can open the horns to clean them. If you can get them open, wire brush as much of the rust away as you can and clean all electrical contacts. You might also have to replace the wires inside the horn. Then put them back together with little screws and nuts and test them, then if they work replace the screws and nuts with rivets (well, that's what you do with Voxbells, anyway).
And if you have voltage at the reassembled horns but the bloody things still refuse to work, just throw them away and buy new ones, still readily available.

Ken
 
mcnicol said:
And if you have voltage at the reassembled horns but the bloody things still refuse to work, just throw them away and buy new ones, still readily available.
Click to expand...

Hang on - don't throw them away just yet. Try tuning them. There should be a little screw with a lock-nut somewhere on the back of the horn. It adjusts the contact point gap. Loosen the lock nut and wind the screw in or out half a turn at a time and try the horn each time. Once you get it hooting, tune for maximum noise.

If they still don't work after all that, you now have permission to throw them away.  :D
 
The universe lets you know what the score is

All the fiamms I've had made there way to a subdued roadside alternatitive

Gave up on horns a long time ago, needless weight
 
Thx guys !  - battery is suspect, found the fluid levels in it were low so ordered a new AGM as hate those old ones anyway hopefully it will cure it. iF not i'll chase other advice
 
I had a croaking Voxbell issue. Brand new too.
Turned out I only had 7 volts at the horn connections.
I have not investigated yet but suspect a poor connection in the horn button assembly in the switchgear.
I bought a relay to fit at the same time.
 
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