Just shoot me now...

[AZboys]

So, I've been lurking around since I bought a used GS500e last summer with a few 'issues'.  1996 with 15,000 miles but bad voltage regulator and one cylinder not firing, leaky head gasket...  a real project:  $700.  So...  I replaced the voltage regulator right away few months ago, and began charging the battery.  I just cleaned the left hand carb and had it purring an hour ago.  However, since I had the tank sitting sideways on the frame,( I had to prime the carbs 3 times as I cleaned and re-fitted them) I must have shorted something and as I revved the motor, I saw some sparks where the tank was touching the frame!  Ugh!  The bike quit running, but the ignition lights and headlight stayed on.  I couldn't find a blown fuse, but I don't think I know where all of them would be.  What scares me is the seriously weak spark I'm getting now.  It won't start.  I can get a very weak spark now and then and even feel the voltage through my gloves, but it's not enough...

Suggestions?  Coils?  I hate electrical work!!! 

[Soloratov]

I can almost guarantee it's a coil that was shorted by the tank. If you had it sitting there cocked to the side, it would be very easy for the bottom rib to knock one of the terminals on the back and either short it, or make it come loose. On the '96 there is only the main fuse to worry about, so if that one is ok, then the problem is somewhere after that. A weak spark on one cylinder will tell you which coil to check.

[Janx101]

Fuse note... it's under a cover next to the one you can see. . (Which is a spare)


sent by willpower and a phone

[AZboys]

Before this, I had nice hot spark that I could hear.  ( almost forgot - I replaced the plugs few months ago: brand new NGKs ) And the bike started fine on only one cylinder... now it won't start at all.  I'm worried both are gone, or something worse.   

I think I found the fuses.  I only found 2, I'll double check in the morning ( I can't even look at it right now ).  One was probably the spare.  Neither were blown.  I guess that's good.  I couldn't have ruined too much I suppose...

electrical troubleshooting can be daunting.

[The Buddha]

Its pretty hard to damage a coil shorting the low voltage side of it. Its near impossible to short the high voltage side with the tank. I think you either damaged the ignitor box - that's the one feeding the low Voltage side or you didn't damage anything.

I have an experiment for you. See if you can make contact with the low voltage side with the tank the way you had kept it on the frame. I have a feeling you wont.

My thought is that you're battery is not as strong as it was when you tried it first.

Running on 1 cylinder can be the auxillary ground. That being bad or not making contact can cause it to lose 1 cyl.
Cool.
buddha.

[AZboys]

That is an interesting thought.  I have been having some trouble with the battery ever since I bought the bike.  Since the voltage regulator wasn't charging properly, the battery was always being drained.  I've been trickle charging it for days here and there... 

Could I have damaged the battery further during my little shocking experience? 

Thanks everyone for the suggestions.  I will keep you posted...

[Soloratov]

Buddha - Couldn't the coil get ruined if the connections are getting loosened and making intermittent contact? Just curious, I would have thought they would be a bit sensitive to that kind of problem...maybe not. I just figure the only place sparks could originate from his tank touching the bike would be around the coil area....well...assuming he had it resting up there and not on top of the battery.

[The Buddha]

"Sparks" are rather vague, you can get some sparks scratching the side stand on the floor too.

But Coils get damaged if you short the high tension side. HT is a load for the coil.
The low tension is a load for the Ignitor. If shorted it could cook the ignitor.

Remember in electricity 0 load = bad, short circuit = 0 or close to 0 ohm.

Weak battery hurts you 2 ways in this situation - not spin up fast enough to get suction to fill the chamber.
And while the power from the battery is sucked up with the starter, it leaves even less for the spark production.

Remember it all runs off the battey. The alternator through the regulator fill the battery, but battery is what sparks, what cranks, what lights up the headlight, honks the horn etc etc

The ignitor has a transistor that when it sees the advancer nose fly past fires off a short sharp pulse pulled from the battery. Usually around 25-30v (and it depends on the transistor's "hFE gain") ... that sharp 30v spike is amplified by the coil to a 30,000v "spark"

The math is like this - you feed the TCI a strong 12v and you get a 30v kick from the TCI so that makes a 30K volt spark from the coil.
You feed it 10v you only manage a 20v (Its not linear in most cases) from the TCI and that gets you 20k volt anaemic spark.

Charge the battery and try it ... you may have not broken anything.

Cool.
Buddha.

[Soloratov]

That helps me understand a bit better, thank you.

[gsJack]

Give it a jump from a non running car battery and try it.

[The Buddha]

That helps me understand a bit better, thank you.

Even until a couple years ago I did not know that.

Its a dead MZ (which has no compression/suction - I know that now) and fiddling every bit of its electrical system including the ignitor box that have shown me what happens. Yes that and trying to repair audio equipment and reading and asking on audiokarma and diyaudio.

Cool.
Buddha.