73 Gen and battery issues

Snake1994 · #1 7th October 2005

Okay,

I'm just starting to work through this "new" Sporty. Since I have a "failure to start" problem I guess it is a good place to start. Here goes:

The battery has 12 volts as it sits. If I place a trickle charge on it, the "trouble" light comes on. Two cells were empty of electrolyte -- could be a problem

After a few hours sitting, the bike starts up quickly ( some backfire). If I shut it off and restart, it will grind out as if the battery is dead. It doesn't matter if I run it for 1 minute or ride it 3 miles, or run it for 20 minutes.

My first instinct is the generator. I don't know why it doesn't affect running, but it is dual iginition with 2 dual dyna coils.

Tonight, the generator read about 8 volts as it ran. I'm going to check it again.

Or, god forbit, it could be a crummy generator that has now ruined the battery.....

Any tricks as to testing the generator?

Thanks

Snake 1994

IronMick · #2 7th October 2005

1. fully charge battery. test battery specific gravity. Load test battery: attach volt meter to battery, disconnect spark plugs, run starter - if voltage goes below 10 the battery is toast.

From the 1979 to 1985 FM:

2. generator output test: remove both gen wires; connect +ve voltmeter lead to "A"; connect -ve lead to ground; start engine run at 2000 rpm; meter should read at least 2 to 2.5 volts

3. Gen max output test: remove both gen wires; connect +ve voltmeter lead to "A"; connect -ve lead to ground; start engine run at 2000 rpm; MOMENTARILY [max 10 seconds else dammage gen] connect a jumper lead from ground to "F"; voltmeter should read 25 to 30 volts

dabronco · #3 7th October 2005

Take a voltage reading from the 'gen' terminal to ground at the regulator. It should swing toward 14 + volts as you rev the engine. They won't charge much below 2000 rpm. A bad battery will act just as you describe. I would start there. If your battery is bad, you'll overwork your regulator, (25 bucks at autozone) or fry your generator,150 bucks on e-bay new.

Snake1994 · #4 7th October 2005

Thanks. I just reran the test on the gen. I had been testing both the generator terminal and the ground terminal from the generator. I just retested using a proper ground and got solid 12v reads at 1500 rpm.

I could not get a 12v read off of both terminals on the generator. I don't know if that means it isn't getting a proper ground, but I imagine it won't make a huge difference.

Between those reads and the "trouble" light on the charger, I'm back to focusing on the battery.

I probably should get a testor.

Thanks !

Fisherman · #5 7th October 2005

Dry cells 'sulfate'. Battery no good. Bad cell. Must replace. Next, why was battery dry? I suspect volt regulator. Overcharging battery. Put in new battery. Start bike, let run for 5 or 10 minutes. With bike still running, check voltage at battery. I think you'll find it 14 to 15 volts. If so, volt reg bad...

Snake1994 · #6 7th October 2005

The guy I got it from didn't ride it and just charged it constantly. So it could be overcharged from external charging (hopefully).

I will check that when I replace the battery. Hopefully tomorrow.

Thanks

Quote:

Originally Posted by Fisherman

Dry cells 'sulfate'. Battery no good. Bad cell. Must replace. Next, why was battery dry? I suspect volt regulator. Overcharging battery. Put in new battery. Start bike, let run for 5 or 10 minutes. With bike still running, check voltage at battery. I think you'll find it 14 to 15 volts. If so, volt reg bad...

Snake1994 · #7 9th October 2005

Well, good news, and bad news...

I got a new battery. Set it up, charged it, put it in and I got about 3 cranks before it started to go sloppy and die. Really pissed me off. Although I am worried I didn't by the biggest GD battery in the shop.

THEN, I got the bright idea to tie it to the car battery YEAH, I know, but I no longer care. SAME results after just 3 or 4 tries -- battery drain ??? WTF?? I mean it's my truck for crying out loud.

SO THEN, WAY PAST THE POINT OF CARING... I started the truck up and went back to start the bike. STILL COULD NOT crank the starter over. Just rumbled a couple of times. Which I kept trying while keeping an eye on the jumper cables over heating...

THEN I noticed a spark coming from under the exhaust. So I rolled it back in the garage to take a look... Each crank the solenoid to starter cable would give a ways and then ARC over to the cam cover. A quick examination of the solenoid showed that the solenoid to starter cable terminal was completely out of the housing. The rear cover of the solenoid was broken and the terminal backing missing.... hmmmm thank you previous owner....

So I jerked the solenoid. On to round two. Hopefully the constant arcing and shorting of the starter wire is a major cause of these problems....

Why to people use random nuts and bolts on their bikes? >> Woops sorry off
topic...

Take care...

Snake

IronMick · #8 9th October 2005

Solenoid cover is plastic. They break easily. The parts fall off or cause these problems. Stupid plastic cover. Idiots. Dummies. Crappy engineering. Who is respobsible for this? Let's string the sucker up, eh. Geeze.

Snake1994 · #9 9th October 2005

Let's face it, it's the EPA's fault.... I know how to save lots of weight -- no electric starter, therefore -- no solenoid, no battery (magneto), no starter... that saves about 40 pounds right there....

Oh and I would have been riding it today instead of working on it....