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Installing Dual Horns over Single Stock Horn

Discussion in 'Modifications and Projects' started by shadowarrior, Dec 5, 2009.

  1. Am planning to install a pair of Hella Disc Dual horns on my ZRX.

    The bike has the stock single horn mounted.

    This is the circuit which I intend to follow, using the existing wires from the stock horns.


    Couple of quick questions:

    The horns are rated at 12v. So am guessing I should rate them as 24V when installed together? or since am installing them on parallel it would just be 12V as total together?

    Also, my stock horn's fuse is rated at 10A. Should I put in a 20A fuse for the dual horns even after using the relay? or should the 10A be fine with the relay there?

    If I choose to run a single 12v horn without relay, (just replacing the stock horn with one of the Hella Disc), would I need to do any other adjustments?

    Also let me know if I am doing anything wrong in the circuit diagram.

  2. A 10 amp fuse is designed to protect things which will fry if they get more than 10 amps (probably with a small margin for fudge).

    If you put in a 20 amp fuse then the fuse won't blow till the higher amps hit. None of that will be a problem if everything else in the circuit can take it or if the circuit pulls less than 10 amps.

    However, you shove 20 amps through the circuit and if the horns and/or wiring and/or horn switch can only take 10 amps, you will blow them instead of a fuse.

    Think of the fuse as a self sacrificing safety valve that in time of emergency chooses to die so others might live. Then compare the cost of a new fuse with a new horn, new wiring or switch and it gives you some idea of what fuses are about.

    You haven't shown a circuit in the wiring but I assume the horns will be earthed which will complete the circuit. However the idea of connecting the two horns to each other looks odd to me. (Have to say though, I am no expert on circuits and will happily bow to the wisdom of others).
  3. You are not quite right with the wiring of the horns, the two horns need to be in Parallel and one side of each should be tied to the frame of the bike, (battery return) if positive switched or to the battery positive if ground switched.
    From your drawing I would say it is positive switched and so the other side of the horn ties to the frame, (Ground/Battery Return)

    Because the two horns are in parallel they If you put them in series they would need 24 volt overall, 12volt each. Not an option in a bike. :)

    As GreyBM said you may need to up rate the fuse that protects the wiring and horn because you are now drawing twice as much current. (Amps)
  4. Have you considered a Stebel nautilus ?
    Compact self contained twin air horn 135 DB
    It is very loud you can pick them up on fleabay for around $50
    I scare the drunks before they step in front of mecoming home from work at night
  5. +1 to the Stebels they are great. In addition to my original post the Kwakas seem to have the horn ground switched from the "brief" look at a wiring diagram I found.
    So in the original wiring the fused positive goes to the horn, the horn goes to the switch on the handlebars and the switch connects to ground.

    Standard Automotive Relay


    In your rewired case the fused positive which used to go to the horn goes to Terminal 30 and 86. The current wire that runs away to your handlebar push button goes to terminal 85.
    Terminal 87 runs to your new horn(s) and the other side of the horn(s) runs to ground or back to the negative of the battery.
  6. hmmm...
    yeah i forgot to mention the earth, since I was just extending the connection from the existing wire of the stock horn. They are earthed from the switch.

    I ll give it a go tomorrow morning. I ll try running a direct fused wire from the positive point of my battery and also the live wire which was already connected to my stock horn.

    I also feel, since the relay has only 3 points (Horn, Switch and Battery), it being mounted on the frame completes the earthing. The horn's brackets gonna be mounted on the frame as well, so if the switch or the relay was not completing the earthing, the horn's brackets would.

    I figured, since the stock single 12v had a 10A fuse for it, I ll bump the fuse to 20A for the dual 12v.

    I already have a pair of Hella discs, so using stebels aint an option for me, though i love the nautilus :|
  7. shadowarrior
    I figured, since the stock single 12v had a 10A fuse for it, I ll bump the fuse to 20A for the dual 12v

    I'm buggered if I can see how you could come up with a wiring diagram as in your first post

    If you don't want logical and correct advice then don't ask!!!!! Read "grey bm"s post properly!! Also the post from cjvfr

    ........or else entertain us with your future stories of burnt wiring etc, just don't expect sympathy.
  8. revhead.
    dont know who you are, and don't care (some random newb who joined some months back). Never found anything interesting from whatever you posted since your registration. So, I would ignore your comment and request you to STFU unless you have any constructive comments to make.

    If you DID see my diagram, I understand you FAILED to notice that I am using the two EXISTING wires used in the stock horn, which ALREADY have an earthing and fuse. The question was about regarding both the horns running on parallel to regard as 12vX2 or not. for which I already got my answer from Grey and Chris's post.

    And here is a bit of entertainment for you. I exactly followed the diagram I posted, to connect the horns, and guess what, they are working.

    Sorry if that's not enough entertainment for you and thanks but can live without your drop of sympathy as well.
  9. shadow what exactly is the purpose of the wire between the 2 horns in your diagram? Is that meant to portray earthing? I think that line has confuddled most of us, and I am glad you got it sorted. Those air horns though are ruddy loud.
  10. hey thera,
    i just connected 1 of the points of both the horns together. I noticed, the rubber clamp where the stock horn was mounted, has a small metal U shaped bracket inside, which touches the horn's main screw. I think that grounds the horns. I also mounted them touching the metal frame, just to be sure.

    I am sure that the old stock horn had one live wire from the battery (spark tested it) so the other had to be the switch, which was grounded either by the switch or those U-shaped brackets where the stock horn was mounted. :|

    hmmm, for some reason, the horns are not sounding loud like they should be. :| a direct connection without relays to a 12v battery (not from the bike) makes them sound good. Let me try and isolate the problem..maybe I need to change the relay :|

    nevermind, just secured the wires properly, and everything is back to normal :)
  11. kill that wire connecting the 2 :) its superfluous from what i can tell.
  12. Shadow, I'm glad your new horns are all sorted, but I think there is something lacking in your understanding or communication.

    Revhead is right, if you wired it exactly as in your diagram, the horns would do exactly nothing. The fact that the horns are earthed should be shown (not assumed to happen through some mounting point somewhere), and the wire between them is doing nothing.

    I would have thought that if the horns are going to draw more than 10A, you should have a new, heavier gauge and separately fused high power feed, and use the original wiring only for the trigger. Using a 20A fuse in a circuit designed for 10A max is asking for trouble.

    Sure, revhead wasn't delicate in his reply, but your response was pretty over the top, considering he was trying to help.

    Anyway, I love that you are installing dual horns - very Indian! (I am assuming you are Indian, based on your list of bikes. Sorry if I'm wrong!)
  13. You should be installing them in parallel. This is the only way for them to both get 12v. In series like that, they will only be getting 6v. The current draw is certainly going to increase and besides the fuse, you might want to consider that you could be overloading the horn relay. Don't know what it's rated at but pretty sure it would only be configured for 1 horn. Really don't see the point in 2 when you can get single units that are more than loud enough.

    Also please learn how to resize/crop images.
  14. If, as per your original diagram, your installation has one terminal of each horn connected to each other by a wire that doesn't have any other connection to it, then you have connected the horns in series. If that is the case, they are each running on 6 volts. As others have said, you need to wire then in parallel to get the full noise. To do that, wire as per the original diagram but the wire between the two horns should also be earthed.
    In order to get the right fuse, you need to know the current draw of the new horns. They each might not be the same as the old one. Also, you need to be sure that the old wiring will handle the extra current. You may need to uprate the wire as well as the fuse.
    Best way is to run a seperate fused wire direct from battery to relay to power the horns.
  15. if your lazy shadow you can fuse each live wire to the horn individually, but that has it's own pro's and con's.