Horn Circuit

[jOe]

1966 XLCH. Known functional horn,known good wiring and button. At above idle,pushing the button does not activate the horn. With the lights on, pushing the button dims the lights and does not activate the horn. The lighting system is completely operational and normal.
Question; Would this indicate a relay in the regulator needs attention? Or does this go back to a capacitor issue?

[EKHKHK56]

Hi Joe. I always verify all grounds clean and tight first. Then same for feeds. If all fine sounds like either you don't have enough power output to the system or you horn is loading down the system like with part bad windings possibly. Can you check the amp draw while you have it test honking? Haha. 12V or 6? Normal charging should be about 13.5-14V and can't remember other but probably 6.5-7V. Couple ideas...

[ambike]

Do your lights burn decently without dimming when you hit the brake light ?

If all is fine in the lighting dept., then with the lights switched off, a known good horn with known good wiring should give an audible peep.

If not, the wire from the button to horn could be grounding. And just maybe that section is making contact when the bike is running & vibrating.

Should be simple enough to check / re-check the horn's wiring. ( determine continuity and measure ohms thru the button when closed )

What did you use to test the horn ? Check it again as it's mounted.

[jOe]

Hi; Yeah, did all that, everything's Strac. Tested the horn with a car battery. Lights don't dim with the brake light on. I'm thinking it's either the horn adjustment screw,point gaps in the regulator relays or the condenser.
Beyond suggesting turning the adjustment screw until it works, the manual really has almost no useful information.

[sportsterpaul]

The horn does not work and you question the voltage regulator. Hmmmm. I would question why you think the horn is "known good". Do you have a magneito bike? Then the horn is not being powered by a battery, but by a generator. I would question the horn switch or the wires going to it. Take the wire off the horn. Connect a wire, it can be a piece of Romex for all that matters, from the battery + or the generator A to the horn. Are you putting a 12V horn pack on a 6V bike? A running bike at 2000 RPM should have 13.7 to 14.2 V at the battery or generator. A horn might well work at 12V but not at 14, they are persnickety. First verify you have a 12V horn in a 12V bike, and explain if its a battery bike or magneto bike with no battery.

Taking the switch and wiring out of the equation is you best bet. Jump the horn to the battery on the bike and see if it beeps. Then start the bike and see if it keeps beeping. Then you attempt to figure out what is wrong. If you start messing with regulator coils you can blow up the lights or boil out the batter, or make the bike stop charging at idle.

[mikeslemmon]

horn on a XLCH tits on a bore

[jOe]

I readjusted the adjustment screw outward until the horn JUST sounded and ran a 12V power supply on the circuit and everything checked ok- good sound. I also cleaned the points on the relay in the regulator. Started it up and it functions, pathetically,but it's almost there. Lights dim much less at idle. I'll ride it around and let the condenser charge, that might do it, unless there's a charging/current issue.
I think the adjustment screw was in to far and the diaphragm wasn't oscillating properly and corroded points was robbing the juice to the lighting system.

But Mike, I got that thing to start on two kicks in the morning, what else can I work on today? Unless I make a trip to the Mobile station.

[jOe]

OK, so now it works, weakly, but it's there..I rode it around a bit and it functioned on and off. I still think it may be the condenser/capacitor.
Is there a source for a replacement capacitor out there?

[ThumpStreet]

Joe,Have you gave the capacitor the simple resistance check?The check I refer to is taking your multimeter on OHMs function,placing the multimeter + lead to the capacitor lead ,multimeter - lead to capacitor case and watch for resistance to build up.Then swap multimeter leads + to case and - to lead.Resistance should dump to zero.If meter shows open line or resistance doesn't build capacitor is suspect.Will not vouch for a quality replacement capacitor,but I have seen V-Twin MFG has an offering.Peter

[sportsterpaul]

If you mean the little capacitor going to the regulator, that is there for radio noise suppression. It takes the switching spikes out of the regulator relays and keeps radiation down. It is way too small to store any large charge, its charge time is about a hundredth of a second, if that. Its not impossible that a bad capacitor would cause horn problems, but huighlly doubtful. Still, capacitors are a low-reliability item, although these noise suppression capacitors do not get hot like a condenser in the circuit breaker of a battery bike, they still can fail.

"Resistance should dump to zero"
Well, a capacitor should be open-circuit and when you measure it one way you are charging it up with the multi-meter ohms test current, and reversing it will dump the charge back into the voltmeter, not enough to blow the fuse in the multimeter with small cap like this, but back down from open-circuit. Depending on the meter, and if the capacitor is a polarized one, the meter may go back to open circuit.

Now if you mean those big aftermarket capacitors the size of a beer can, well yeah, they hold enough charge to take a little flicker out of the headlamp at idle. They charge up in a tenth of a second. They are definitely polarized types, and they do fail with vibration and temperature. If you have one of those, it never hurts to replace it, and it might take enough ripple out of the generator output that it would affect the horn.

Its well-known that any horn is persnickety. You still have not ruled out the handlebar switch, which may well be high resistance or intermittent. It is a really crappy switch.