Forum bmwbike.com

I am trying to figure out whether it is really necessary to modify a 6 volt, standard KLAXON horn if a 12 volt system is installed on a /2. I have found only 1 out of 4 that claimed one needs to change the horn in question to 12 volt! Others say that the horn will only sound louder. I have taken the horn appart to see how it functions. (brought back some good/bad memories from a text book I still keep from University (Electricity and Magnetism). My understanding (someone please correct me if I err) is that using a 12 volt supply on the horn doubles the current flow to the horn's system. This increased current flow translates into a proportional opening and closing of the points/mechanism, i.e. doubled frequency......this is why the horn sounds louder. Information tells me that since the horn is not something one uses continually, leaving the 6 volt system unmodified is OK. I guess my question is: If Klaxon manufactured both the 6 volt and 12 volt versions using the same outer design, then what modifications were done in the internal components. If they never manufactured a 12 volt system then is there an expert out there that can tell me what I need to do. All I can think of at the moment is putting an in line resistance. Not knowing what the normal current draw is, I have no idea what this resistance could be. So, anyone with sound advice please echo your knowledge.

Pierre-

Having done this conversion, I can say that the 6V horn will work...for a while. It will be
VERY loud, but will eventually burn out. Mine did, anyway.

Hella makes a 12V horn which looks very similar to the Klaxon. I think it was made
as a replacement for /7 horns. It has a nice tone, fits on the bike and works well. It's
probably also cheaper than a 12V Klaxon, if you can find it.

Jeff,

I have a back up plan if nobody comes up with a proper conversion for my Klaxon. I found a FIAMM model HF90 HIGH horn that sells for about US$16 at Canadian Tire over here that will fit nicely and securely inside the Klaxon Shell. Thanks for sharing your experience the hard way......seeing is believing!

Too bad I sold the burnt out Klaxon!!!! Thanks for the info, though.