HB: Handlebars Horn earthing

[kettlrj]

I have just finished wiring a Comet for a section member. The Comet is fitted with painted handlebars. To activate the horn, the button needs to be grounded to the handlebar, which is not possible without removing some of the paint and even if this had been done the bars would not go to ground through the handlebar clamps. In the end I connected a short wire from the horn button/dip switch to one of the handlebar clamping nuts. Question is, how do other folks do it and how did the factory do it ?
Richard

 

[b'knighted]

I don't know what the factory did but I'd use a longer bit of wire and connect from the horn button clamp back to the earthing bolt thread at he front left of he UFM, or if you have run an earthing wire to the headlamp shell you could use that. It is less than ideal to rely on the head bearings to carry the earthing current.

 

[bmetcalf]

I have an earthing wire from the headlight to the ufm to minimize the current through the bearings. I also scraped the paint off for the horn button.

 

[kerry]

Ironic Richard, On my Prince I just replaced Chrome bars with painted ones and even though I filed a bit under the horn button it would still not work, I then ran a short wire to the clutch lever screw and then it did ? odd because under that was paint too. Kerry.

 

[Simon Dinsdale]

Ironic Richard, On my Prince I just replaced Chrome bars with painted ones and even though I filed a bit under the horn button it would still not work, I then ran a short wire to the clutch lever screw and then it did ? odd because under that was paint too. Kerry.

Kerry, your clutch lever isn't just electrically earthed to the bike through the handlebars. As the clutch cable inner & outer are metal then another earth path could be through the cable to the engine. You will be amazed how electricity finds a path.

Simon

 

[kerry]

Hi Simon, You must be right, I tried a piece of wire first and got a connection, it works fine. !

 

[vibrac]

Of course when I started to go to the dark side I found that the neat cheap all in one handlebar control from Japan etc that I used for indicators had a horn button that used the live side to trigger the horn. In many ways including the use of 6v horns on 12v bikes this is a safer option rather than a short that fires the continuous horn and fire risk. As I found on non indicator bikes with painted bars if you need to bring an earth wire to the horn button it begs the question are there individual handlebar buttons that switch the live side?

 

[Chris Launders]

On several of my bikes I use old style Harley Davidson ones, these are available in one and two wire options to use as horn, cutout or starter buttons, drill holes in the bars and run the wires internally, they are fastened on with two self tappers.

 

[oexing]

Old British standard or not, an extra earthing wire between headlamp shell and rest of bike should be fitted anyway. No surprise otherwise about questionable electrics , poor lighting and horn when all current of bulbs and horn puts high loads on head lug bearing balls - super , like arc welding the balls . . . . unbelievable crap idea !
A horn takes quite a few amps really so not a bad idea to just operate a horn relay with the handlebar switch and keep it in shape for decades thanks to the relay.

Vic

 

[erik]

To my mind a relay is not so important because in the more northern countrys the horn butten is one of the parts of a bike which stay untouched for weeks and month.Sometimes only the Mot test is the place to use the horn.So no Problem for the Points of the switch to survive Long times.And Vic you are Right thata good eathing is essential.Therefor on my bikes not only the headlamp is earthed by separate wire ,the RFM ,too. Erik