Bike Dies When Start Button Released

[Dr. Frankenstein]

Another problem for 'Rusty,' my 78 GL1000...

I put the oil back in Rusty and started her up, just lubing the internals; oil looks good, no more bubbles...but she's idling along fine, I'm revving the engine occasionally, just lubing her up. She's idling fine for about, oh, 5 - 7 minutes, and then dies. Thinking she was just out of gas, I took a peek inside the tank - gas is fine. Half a tank. Plenty of flow through the line.

I try to start her up and she does, but the second I take my finger off the Start button, she dies. The bike will run with it pressed in, but release it and she dies.

I'm thinking a connection in the starter button assembly...? It's not the ballast resistor, I'm running electronic ignition and took that out...

A little more information: I just went out and started her again like normal - pressed but did not hold the Start button, she starts and runs fine for about 2 - 3 minutes, then dies. She's getting gas, FWIW the Temperature gauge is nowhere near 'Hot'...same problem repeats itself, though - she'll fire if you hold in the starter button, dies when you release it. A bad ground, maybe...? There's something in my brain that tells me this is really simple...

[Oldboy]

Kill switch?

[gltriker]

[ritalz]

I would check the connections where you eliminated the ballast resister.

[Whiskerfish]

I would check the connections where you eliminated the ballast resister.

[Dr. Frankenstein]

..."check the connections where you eliminated the ballast resister."
So that might have something to do with the intermittent stalling...? In this pic the yellow and blue wires come from the coils and go into their respective slots, and that black loop is the two spots where the old ballast resistor plugged in. As per cfairweather's instructions, I effectively looped/joined those two wires together, bypassing the resistor.
DSCN2321 by Dr. Frankenstein1, on Flickr

The only thing I can think of is that black plastic connector seems a bit loose, so I will check it out, see if I can't tighten it up a bit. I did take it apart and clean all the male connections shiny-bright, so maybe some are not in their respective female connectors when I reattached it, or maybe crud on the inside of the female parts. I did spray them all down with CRC contact cleaner though...I have a whole container of matching spade connectors, so I might just change out the whole thing to get a tight, clean fit, but I will as usual report back.

Hmmm...although the more I look at it, the more it seems like those two black wires are sitting proud of their slots...look at how deep the yellow and blue wires go compared to the black ones...I thought I had them in there all nice and tight, but I'll double-check those. But would the bike still start if those were not making contact...?

Cliff, that's a nice test probe you have there...what/how are you suggesting I probe, specifically?

[redglbx]

When it dies is the headlight on and fairly bright like when it’s running ?

[Dr. Frankenstein]

Hi Red; I think so...the headlight cuts out when I press the button but comes back on when I release it - but I will double-check and report.

[Sidecar Bob]

That is normal. The Start button has a second set of contacts that turns off the headlight while the Starter motor is running so that more power is available for the starter.

Have a look at the wiring drawing for your model (if you don't have the colour version follow the link in my signature to get it).
In the stock configuration as shown in the drawing, when you are not pressing the Start button power from the black wire (switched power) goes to the kill switch (engine stop switch) via the resistor and from the kill switch to the coils (in your case it would go to the kill switch via the jumper wire you installed in place of the resistor).
When you press the Start button power from the black wire (switched power) is sent to the solenoid ("starter magnetic switch"), which in turn allows power to go to the starter motor. BUT power also goes via the diode to the kill switch (without passing through the resistor) and from the kill switch to the coils.

That means that there will be power to the coils (& thus spark) while you hold the button even if the resistor (or your jumper to bypass it) is completely missing but once you release the button there will be no power to the coils if there is something wrong with the jumper or the way it is connected.

I would start by checking if the ends of that jumper are plugged onto the mating connector properly and if the terminals are connected to the wire properly.

[redglbx]

^^^ what Bob said !