Blowing my own trumpet, with a horn upgrade - OR NOT!

[Descolada]

I am in need of a little help from someone with a better understanding of strom electrics than myself. For the second time in recent months I tried to complete a horn upgrade from the stock "chirp" horn to a set of FIAMM Trumpet Horns. These things are rated 12-24 volts and if I connect one to the stock horn system it works with no bother. However, when I attach the second all I get is a 'thunk' from the horns. It suggests that there is not enough voltage to get both going at the same time. These came with a relay but I hoped to have them simply run through the stock system as it already has a power supply, a relay and button.

Do any of you more knowledgable folks understand why I might be seeing this behavour, or do you think that they will only both work when placed on a 24 volt system?

[willbo]

Hmmm. Something about this joggs my memory. Well, in this case a steble horn upgrade. I'm sure a wiring kit was needed for a upgrade as the standard couldn't do it, but maybe its just my lil grey cells confusing themselves

[MartinW]

Have you connected them in series or parallel ? If they are in series they only get 6V each.

Sorry if that's a basic question, don't know how much you know about electrics.

[bosnjo]

I upgraded mine to double horn (I call them "truck horns"), very loud.
So...
First of all, take both horns, make parallel connection between them and then touch with the wires straight on the battery terminals. Is it sounding right? If it doesn't, something is wrong with the horns. If it does, then you proceed to the next step.
You better don't even think of using power from the OEM horn. Even if there was enough "juice" from that cable, you risk burning the horn switch on the handlebars and that will end as a costly repair. That is the reason they come with relay.
Basically, you use OEM horn power source only to trigger the relay, but real power source for your horn is straight from the battery, with inline fuse. That is the propper way to do it and the only safe way.
If you don't have knowledge of wiring the relay, tell me and I'll make you a little diagram. Wiring is simple, complicated is running the wires from the front to the battery and the from the battery to the front. But if you take your time and do it slowly using a lot of zip ties along the way, it ends up nice. The most of my time I've spent looking for the place to hang new horns. OEM horn was impossible to remove, the nut was so tight. So, I ended up hanging them on the right side of the bike and left OEM horn in its place, disconnected.

[Descolada]

Don't be sorry. You estimate my abilities quite properly. I had them test connected in Parallel. Tomorrow I will try again, but also incorprate the vital information provided by bosnjo below.

Thank you for your help MartinW!

[Descolada]

Bosnjo.

Outstanding information. Thank you. It explained the need for the relay fully.

Yes, there are instructions with the horns but I couldn't answer the basic question in order to proceed with the right diagram. The questions were "Grounded Horn button", "Horn button connected to positive"?

The horns have twin contacts on each horn. Neither are marked as positive or negative.

[Gassoon]

Des, maybe this link might help (or not, its for a stebel , but for basic principles)

viewtopic.php?f=58&t=7610&p=61044&hilit=horn#p61044

[Descolada]

Very good, thanks Gassoon. I will take a look again in the morning.

[iansoady]

I always fit a relay with extra horns as it reduces the load and arcing on the horn button.

Where did you fit them? This is what I did with my Tiger:





but I can't find a similar position for the Wee.

[bosnjo]

Here I made a little diagram on how to connect new horns. Don't worry about polarity of wires coming from OEM horn, they just serve to trigger the relay and the polarity doesn't matter.
Make sure positive from battery goes as on the picture.
On new horns, I also didn't care about polarity, as long as both horns are turned the same way, I mean, parallel contact to be done is, for example, left terminal on one horn to left terminal on the other horn, then right one on the right one, you know what I mean.
Anyway, here it is:

[Gassoon]

Excellent diagram, bosnjo!    

[Descolada]

bosnjo, that's outstanding - thank's very much for posting this diagram. It's pissing down today so I have had to postpone the horn mod YET AGAIN!  :angry-screaming:

But it's OK, I still had to spend an hour in the rain putting back together all the stuff I started yesterday. My bottle of ACF50 has never seen such use. I have managed to repair the (accessory) light fault and complete the installation of my RAM mount for the GPS (thinking of ST7 here).

Strange but if you can get past the fact that it's blowing a gale and raining like you're in a waterfall and the fact that you have two pairs of latex gloves as well as a pair of protective work gloves on top of that you can actually start to ignore it and just "become one" with what you have to do.

Perverse I know