So riding home yesterday I came off the exit ramp on the highway and my 78 just turned off. The bike has not been acting any differently recently and has been running well, battery has been holding a steady and strong charge for a month without charging, starting up every time easily.

THe only difference in my ride that day was the lack of traffic, allowing me to take some turns the way I like to (leaning in!). Otherwise it was a regular day. The bike has fuel at the carb. When I turn the key on nothing happens, no lights, no horn and definitely no starter.

I will have time to look at everything tomorrow, I will start with the battery and its connections and work back from there. Anyone have and tips or know if any of this sounds familiar?

 

Twice i had that happen in the last couple of years. Both times the battery was completely dead. The battery showed 12 volts but would not take a charge, and would drop to zero volts under even a very light load. Both batteries were only a few months old.

Some years ago it happened, the -ve battery cable was loose. I fixed it on the side of the road.

The circuit starts at the batt+, runs to the 30 amp MAIN circuit breaker, then to the B ignition key switch terminal, then to the IGN ans ACC circuit breakers. If no obvious faults here i would try to charge the batter off the bike.

Watch it because, in my experience, if the batt is toast the battery charger may get wrecked from overheating.

 

I agree with checking the battery connections and battery cables. The cables can sometimes look OK on the outside and be corroded or broken inside the insulation. Disconnect both from the battery and give each one a light pull on the connector.

Mine died similar to yours in 2004 at Sturgis and it turned out to be a battery cable. As I moved the battery slightly to get a better angle at removing the bolt connecting the cable to the battery, the corroded cable end fell right out of the ring connector. Not sure if it was a bad crimp job at the factory, or if it just corroded over time.

 

As suggested, definitely sounds electrical.

While it could be anything..... the connections to ground would be my first checks. Specifically:

• -ve battery cable
• ground wire off the voltage regulator

Where these bolt/connect to the motor on my '71 have been trouble spots for me over the years. Your '78 may bolt/connect elsewhere.

..... and even if they look good, an intermittent / flaky ground connection is all it takes to park you on the side of the road.

Get out your multimeter, and work the problem. You should be able to isolate it quick enough.

 

that has hapend to me twice, both times the key switch came loose and a wire on the back of my key switch shorted out to the backet and kept popping the main breaker, when you turn the key on listen carefully and see if you can hear the breaker kick off

 

Thanks for all the tips guys, I'll be out there with my multimeter in a few hours. THe ground cable has been suspect to me since day one, its just a big flat braid of copper wrapped in electrical tape, cleaned a lot of corrosion off of it before starting the first time. There are no ring terminals, just holes punched through the braid!

 

Another trick I use to confirm a flaky "primary" ground....

• without disturbing any existing ground wires, run another temporary ground wire from the battery to frame.

A wire with alligator clips usually works well..... but use whatever you got handy..... just make sure you have good connections at both ends.

If the problem disappears/reappears as you attach/detach the temporary ground wire.... then you know your "primary" ground is highly suspect

.... and keep in the back of your mind.... when troubleshooting electrical problems, you could always have more than 1 problem.

 

First things first, battery is dead. It read 0v on the bike, 1v off the bike, and after 10 mins on the charger is up to 3v. The electrolyte levels are all good. Checked continuity from my ground strap to the frame, was fine.

Did not hear any clicking of breakers when I switched the key on. I will monitor the charger to make sure it does not fry. The battery is a Harley Davidson one, got from the dealer in October so its still within its 6 months warranty.

 

Give thanks that you had the 30 amp MAIN breaker. Some model years have only the other three. Two stories in recent years of IronHeads without this breaker catching fire in the same circumstance.

Not much you can do other than stand and watch, or urinate on it hoping.

If you do not have the 30 amp MAIN on your model best to install one.

 

So I charged the battery about 24 hours to 13v. Put the battery in and the lights all turn on and the bike turns on. Battery dips to 10v while starting but quickly goes back to 12v after its fired up.

I turned it off and tried again. Lights are on but bike wouldn't start. I jiggled the kill switch and midway between off and run, the bike started up. Took it for a 5 mile ride, battery still at 12v but still need to rock the kill switch when starting.

Would a sticky or bad kill switch completely drain the battery? There is no spark when I brush the grounding strap on the negative battery terminal (with the positive connected). I am kind of at a loss for why my battery died after a 20 minute ride.