Attention GS Detectives: I've got a weak spark...any ideas?

[maynard]

On my 850GL, I tore down the electrical system after some one let the battery eat through most of the wiring. I KNOW I have everything wired correctly. I did think that I might have a weak ground connection, because I painted the frame and battery box, so I double checked those and made sure I have bare metal to bare metal contact on all the grounds...it's all good.

NOW...I do have spark, but it's weak. So weak that gas is actually not burning. It will fire with starter fluid, but won't stay running. Pretty sure the plugs are good, they are new. The gaps are correct. I swapped out the Ignitor box for a spare, still nothing. (though I did cheat, I just unplugged the one and plugged the other in without mounting it to the battery box, so maybe it wasn't grounded enough to work?...but I doubt it) I have a spare set of coils, but the odds of both coils going bad simultaneously are pretty slim I'd guess. I am going to go have those checked at a bike shop. I am suspecting the signal generator, but I don't understand enough of how that thing works to actually point the finger at it. The bike ran fine 3 weeks ago prior to the electric rebuild, but now, it will not fire up. Is there something I missed or should I swap out that signal generator? Or am I WAY off base here? HELP GUYS!

[nabrams]

I'm assuming you have a fully charged battery.
Have you verified voltage at the coils? If it's less than 11 volts then something is robbing current on the way there.
I doubt it's the signal generator - those rarely break.
Anyway, the best thing to do is verify voltage at various loactions between the battery and the coils. Better to know than play guessing games.
If you hook up the bike to the battery of a NON-running car, does it run better? If so, your charging system or something else may be robbing your bike's electrical power. Disconnect all non-essential circuits, like the head-light, tail-light, charging system - yes, your bike should run for at least a couple of hours without a charging system if the battery is fully charged. Does it run better now? I think you get the picture. Of course, you will need a multi-meter to diagnose all this.

[nabrams]

And, of course, there's always everyone's favorite - dirty electrical connections.

[wiredgeorge]

Just for grins, there is a bit of diagnostics and symptoms in this article that set up the need to do the mod described:

I suspect that this mod would benefit about 95 percent of the pre 1985 bikes on the road...

http://kzrider.com/component/option,com_docman/task,doc_details/gid,106/Itemid,231/