wr450f 2007 horn problem please help

Hi thumpertalkers

I just bought a 2007 wr450f great bike. The previous owner took the indicators mirror etc because he was using it off road.

However bike is road reg and I have put the rear lights indicators etc all on apart from the horn which I did connect but it not loud at all actually you can barely hear it.  The factory horn is a 6volt. I  did buy a new horn and that did the same. I connected the horn to a 12 volt battery and it was loud.

I REALISED that im missing the horn amplifier. I did call Yamaha dealers here in Melbourne Australia and apparently they need to order it from japan (4weeks wait).  I also tested the plugs that plug into the horn to see how many volts is getting to the horn it was only 0.35 volts and I was wondering what the problem could be is it because im missing horn amplifier? is there a problem with the volts im receiving? just want to thank in advance for everyones help.



I just looked at the manual for an 07 and there is no mention of a horn at all

Unless Yamaha equips these things very differently in your country, you most likely have some sort of Horn that was added after market

Why in the world someone would use a 6V horn and an amplifier is beyond me

The bike is 12V and there are plenty of nice 12V horns out there

A horn is the simplest circuit on a bike

Needs a source of power that is on when bike is running only, interrupt it with a momentary switch like on a doorbell


I think you have some sort of rube goldberg aftermarket

I'd be inclined to do it right and just get a new horn, use the proper 12V source and re-use the existing handlebar button you have

Oz bikes came fully road legal with lights, indicators, licence plate bracket & horn

I believe the 'amplifier' is a relay (different countries, different vernacular), so the switch gear is not over loaded. In a pinch, you could rig the wires to bypass it but only for the short term.


Most horn buttons are a switch to ground, meaning there should never be power at the wire going to the bar. The other wire going to the horn should be 'hot' all the time tha main power is one.

Do you now where I can download a free manual for my bike ive been looking everywhere with no luck

I got it to work I found a plug at the front with power and I tapped into it and used the horn switch cable and its all good now thanks everyone for your input muchly appreciated.

just wanted to inform anyone having the problem I had your factory bracket is too thick for your horn I used the thin bracket that came with my new horn and now it works great. cheers

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