I posted a problem in the electrical section...but that forum doesnt get much traffic. Can one of you awesome riders take a peek at https://www.hdforums.com/forum/ignition-tuner-ecm-fuel-injection/278402-runaway-starter.html
and let me know what you think?

(basically my starter started and wouldnt stop - rolling the motor until the battery died!)

 

A relay short could cause this and I have had miss alignment of the clutch drum / ring gear to the starter drive case the starter drive to not release as it should.
Charge your battery back up with the cables removed.
check all of the primary and secondary cables and wire in the starter circuit for shorts or heat damage due to the excessive starter draw.
once charged touch the cable to the battery and see if the starter still wants to engage.
if not the started drive may have been stuck in the ring gear.
time to pull the outer primary and take a look.

 

That can be caused by the solenoid sticking as you guessed. Sometimes rapping on the solenoid with a screwdriver handle is enough to get it to release. It can also be caused by a stuck or shorted starter button. It happened to mine a few times. Once it was the button the other times it was the solenoid. My guess is that if you disassemble the solenoid you will find the contact plate pitted and burnt. They can be rebuilt by reversing the plate and cleaning up the bottom of the large contacts. The aftermarket solenoids are not very good and I went through a lot and a bunch of rebuild kits before I found a NOS Harley Solenoid.

 

Also if your battery voltage is low the contacts in the solenoid will weld closed. (low voltage = high amp draw)

 

actually I = V / R
so as voltage drops so does current for the same resistance

 

OK. Just got back from work and put the battery on the charger....
The neg battery wire connections to the frame are electrically fine, and from the ground wire to the starter body is 0 ohms.

The pos lead is a 0 ohm ground to the frame. Crap.

Checked the starter switch, intermittent contact when the switch is closed, but the short doesn't seem to be there. Gotta find the relay (gotta love home-made bikes that you didn't build)

I got a schematic and am pretty good at reading them, so off we go!

Anyone got a schematic of the starter connections? I know what the two main lugs are, but there are more wires and connections back there. I will look for a diagram also, just thought I would ask.

 

A weak battery can cause this condition What happens you hit the start button the solenoid throws out the starter gear to the clutch ring gear the battery tries to turn the motor over ( not enough ***** ) the gear gets hung up because the engine didn't start to throw out the starter gear and then we have what is called an emergency situation !

 

The bike did not start... I dont understand why a stuck gear in the ring would cause the starter to not stop after the start button was released with the bike not running.

 

Just a question, before this happened the starter rolled the motor over really slowly and after three compression strokes the bike would start. Battery voltage was always fine and the motor is relatively stock (mid eighties STD engine).

I am really starting to think that I have a weak ground somewhere. How do I check voltage drop at the starter once this short is fixed?

 

I have personally had the situation sqdealgeorge described. More than once! It was a defective battery. The starter gear engages, the starter motor starts to run (slowly), the starter gears are held engaged due to the torque that is applied. The solenoid pull-in coil voltage is reversed when you release the starter button (which I have assumed counters the hold-in coil) and the solenoid spring is not strong enough to move the linkage back to the disengaged position. I can also imagine that the starter contacts could get welded together under those conditions.
Here's another "fun" situation. With the spark plugs removed, I tried spinning the engine with the starter...when I released the starter button, the engine continued to spin then as well. With the plugs installed, it would not do that. I pulled the plugs again and tried it once more with the same result.
The only way I could stop the whole mess from dragging the battery down as well as melting the battery case and cables was to disconnect the battery ground at the frame as quickly as possible.