Hey all,
It's been a long time since I showed my face around here. I had a beautiful, clean, 2001 GS500 as my first motorcycle... sold that to convert an XR400R for street use, sold that and bought a 92 GS500 that didn't run. Cleaned the carbs, rode it for a summer, and then went for "one last ride" September of 2013. For whatever reason, the ol' girl decided to leave her oil all over the highway, my boot, the rear tire, and brake disc on that fateful ride. I decided "well I've always wanted to restore a motorcycle" and tore into the bike. Almost 3 years later, my GS has a freshly painted frame and motor, some new bits, and is nearly ready to hit the road again. One issue so far...
When I crank the bike over, it cranks very slowly and A LOT of heat is coming off the positive battery cable. My gut (and electrical engineer coworkers) say it is probably a bad ground somewhere in the starter circuit. I have completely removed the paint off the engine ground, and where the starter motor ground lugs sit. Also cleaned all the battery and ground cable connections. Still lots of heat and not a lot of starting. Before I put the bike away the starting circuit worked fine, to the best of my memory. Certainly didn't melt the positive battery boot like it is now...
I did notice that I have 3 plugs without mates. One is a black and white cable that runs from the same loom as the two cables for the turn signal relay. The other 2 are in the headlight, IIRC they are brown and orange? My Haynes wiring harness says these colors are for the "position lamp" but all of the lights are working already (headlight, high beam, tail light, brake light, 4 turn signals, dash illumination, oil lamp, turn signal lamp, neutral lamp, and high beam lamp). I also don't have any wires left in my bin o' parts.
Any thoughts on this? Am I supposed to have 3 unmated plugs? My bike is a 92 US spec, if that is worth anything in this discussion
Those three unmated plugs are normal. I had them on mine too, also a '92 US.
Buy a new battery.
The wiring diagram shows the starter motor itself being grounded to the frame, while the starter relay is hardwired back to the neg terminal. You could try running a new ground strap to the frame to rule out a bad ground on the motor, or check ground connections. Cheaper than a new battery if that's the problem.
"well I've always wanted to restore a motorcycle" and tore into the bike. Almost 3 years later,
3 years later??
Buy a new battery.
That's the most expensive way to figure out if you need a new battery :)
I'm also gonna say try running an alternative ground along with the hard-wired negative to rule out any breaks in the wire.
But purchase a new battery, also. If that battery has just sat for more than a year, I'd replace it. Chances are with all that sitting for so long..... It has lost it's ability to hold a charge.
All the electrical grounds go back to the negative terminal on the battery, there are no places where the electricals ground to the frame.
I also think you need a new battery. If you leave a battery discharged for even a few days it'll be ruined.
Quote from: lucas on June 10, 2016, 08:09:33 AM
All the electrical grounds go back to the negative terminal on the battery, there are no places where the electricals ground to the frame.
The "ground" is the frame/engine, no? There are a bunch of circuits that are completed via the frame, including the starter motor according to my wiring diagram. Maybe I misunderstood.
Edit: maybe not via the frame per se, but an alt ground to any exposed metal on the frame would work as well
So you tore into bike 3 yrs ago, etc....maybe those 12:1 pistons are just too much for your starter :nono:
Seriously... Is your positive battery cable and its connections any good, since that is the part that is getting hot?
8)
If the bike isnt starting and your just cranking it over the weakest link will heat up. May sure battery if fully charged or as others suggest..after 3 years the battery is likely toast as well.
There aren't any frame grounds, if you're looking at the GS500 wiring diagram and you see an image like this
(https://upload.wikimedia.org/wikipedia/commons/thumb/9/91/Earth_Ground.svg/2000px-Earth_Ground.svg.png)
then that means it is connected to the engine which is connected to the negative terminal of the battery. You may have seen frame grounds on other motorcycles and cars where they will take advantage of the common ground to run single wires to sensors, etc and reduce the amount of wire used. Some things like the starter and oil pressure sensor on the GS500 like the oil pressure sensor use the engine ground - that is a strap that runs from the back of the cylinders to the negative terminal of the battery.
Maybe it will help to explain that on cars/motorcycles that use frame grounds the frame is also connected to the negative terminal of the battery. In those cases the frame is just used as though it were one huge electrical wire that all the other sensors and things can use as a path to the negative terminal of the battery. On the GS500 it is just the engine that is grounded to the negative terminal of the battery, not the frame.
If a person was inclined to they could run all grounds through the frame and then from the frame to the negative terminal of the battery.
Quote from: lucas on June 10, 2016, 01:00:38 PM
If a person was inclined to they could run all grounds through the frame and then from the frame to the negative terminal of the battery.
Is the engine not electrically connected to the frame?
Quote from: lucas on June 10, 2016, 12:37:28 PM
On the GS500 it is just the engine that is grounded to the negative terminal of the battery, not the frame.
Get your meter out and see if there is voltage between the + terminal and anywhere on the frame.
I think you may be in for a surprise
I realize there is connectivity between the frame and the engine. On my bike there is lots of resistance, there is probably grime or something between the engine, engine bolts, and the frame.
Quote from: VWAG on June 09, 2016, 07:10:31 PM
When I crank the bike over, it cranks very slowly and A LOT of heat is coming off the positive battery cable.
I agree with Weedy64, where there is heat, there is resistance, the above sentence tells me you have a bad connection on the positive battery cable.