Dodgy horn?

A conundrum for the electrically knowledgeable. Horn on bike works fine with the engine running but is reduced to a feeble squeak when not. At first thought a battery problem but I keep it on a trickle charge when not in use, also there's enough power to start the bike with no problem at all which suggests that the battery is strong.
Any ideas?

 

Does the horn have an 'adjusting screw'?

It may be that the contact is a bit corroded, but the vibrations from the running engine are enough to beat it.

Try screwing it in and back out, then adjusting to the 'best setting'.

 

Good call. I'll have a poke around.

 

Horns don't get used much (outside India) and corroded make/break contact faces can be an issue.

There may be two adjustments, a central one and a small screw off to one side. 'Working' them, whilst power is applied, may give a clue. As might tapping it with a small hammer. If there are two screws, my money would be on the non-central one.

It may just be that the engine vibes are 'wiping' the contacts a bit.



If the weather has access, then the steel of the adjusting screw may be corroding away from the other contact, increasing the gap to 'almost' too great an extent to start the oscillation going.

 

Turned out to be dirty contacts. It's pretty sheltered under the fairing but the connectors are on the underside so get what little crap that does get through.
Cheers.