Just found this......Motrax - HOOTAZ (TWIN PACK) - BLACK
more info!
TDMalcolm

I've got the Nautilus on my car, it's plenty loud enough ,but for the bike I've got it's little brother, the Stebel Magnum. It's monotone rather than the Nautilus's dual tone, but it the same volume, a third of the weight, and draws a small enough current that it runs quite happily off the wiring from my original Yamaha horn without need a relay. In the UK some branches of Halfords sell them.

This is the horn i have on my TDM900....verey very loud!!
TDMalcolm

I used to have the larger Nautilus fitted to my old ZZR250, it came with a relay but with no wiring diagram, after getting it working, Dont push the horn button while your ears are anywhere near the horn, OR YOU WILL GO DEAF.

Also you will get used the look of people in there cars looking for lorries as when a bike is behind them there are like "ooh lorries where is the lorries" then you drive past and give them the fingers cause they pulled out in front of you.

It is a great horn but i might have to get the new compact one like mentioned at the start of this thread. The only probelm is i dont know where i can fit it on my XT660R, i think i might have to place it out in the open somewhere but dont fancy doing that as there are not that many places to put it.

Great horn buy one and you will not be dissapointed.

Horn measurements;

Made with a 'Quest 215 Sound Level Meter' at a distance of 1 meter from the horn, readings in dBArel0 (dB - logarithmic scale, A weighting for human ear, relative to the threshold of hearing at 0). For those who don't know (or need reminding) the smallest increment in loudness that a human can determine by ear is a change of 3dB... Note that no corrections were done for the two tones .. thus the reading in dBA rather than phones (for the people who understand such things, I lack the time to perform this measurement nor do I think it would help my decision. No expert in this field .. but from a little reading two tones can 'sound' louder than a sigle tone of the same sould pressure level).


Tested on a Suzuki DR650 driven by a relay through a 30 amp fuse, mounted on the right rear of the bike. Horns were mounted with the correct physical mountings as supplied with the horns on the original bikes. The Stebel used the mounting provided by the manufacture.

Suzuki DR650 horn standard marked 105 dB - facing directly to meter ... 110 dBA

BMW/Fiamm twin horns - facing down, slight obstruction to meter ... 116 dBA
BMW/Fiamm hi tone only - facing down, slight obstruction to meter ... 113 dBA
BMW/Fiamm low tone - facing down, slight obstruction to meter ... 114 dBA

Stebel nautilus air horn with plastic tube fitting but no tube - facing directly to meter ... 120 dBA

Notes:
I was surprised at the DR650 horn being so loud ... I think that the standard mounting position masks some of the sound so leading to the lower perceived volume. The horn tested has had very little use and is in new condition.

I like the BMW/Fiamm twin horns as if one fails you still have one to sound off. They also sound like a car so making a hole that size might be a good thing? These horns came from a 'bone yard' so have had many years of exposure. They were not 'tuned' or serviced in any way!

The Stebel air horn is new.

Measurement accuracy:
Looks like 1 dB .. relative from one measurement to another. The instrument resolution is 1 dB too.

My conclusion:
I'll be using the BMW/Fiamm twin horns for my perception of their failure mode and failure rate. They are also fairly loud.

"It is, of course, better to know useless things than to know nothing." – Seneca

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Regards Frank Warner
motorcycles BMW R80 G/S 1981, BMW K11LT 1993, BMW K75 G/S

I've read somewhere that the Stebel horn is badly affected by water. It lost most of its voice till it dried out again. The implication being that it's best used behind bodywork. If you want one, try nippynormans at half the price of Motrax. Linzi.

Umm it is the air inlet for the air compressor ... it does not like to try compressing water I'd think. They give you a plastic fitting so you can fit a hose to take the air inlet some where water won't be ...

__________________
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Regards Frank Warner
motorcycles BMW R80 G/S 1981, BMW K11LT 1993, BMW K75 G/S

Good point. I didn't even bother thinking why. I've still got twin Fiamms on my bike but fancied something to move a camel out of the way in Morocco. Loud and no water. Fits the bill nicely. Linzi.