81GS650L - Battery Box Negative Wire?

[DaveP]

Had to remove the battery box today to allow removal of the intake boots. I have a question on a wire coming off the negative terminal of the battery.



Coming off the negative battery cable there is a black wire with a yellow stripe that connects to the battery box mount. Seems to make sense to ground the negative terminal. However, there is a short second black wire with yellow stripe coming off the mount (laying in the battery box).

Wiring diagram does not appear to show anything coming off of the negative side of the battery. Where does this wire go?

Thanks,
Dave

[OldVet66]

That is a harness system ground. It mounts on your electrical mounting plate for the solenoid and R/R. The plate is isolated from the frame ground with rubber vibration dampers. If you leave it off your solenoid will not work. It is way too small for the R/R so you should run another heavier ground to that plate directly to the battery negative.

[tom203]

Run a 14 gauge wire from that bolt up to plate that holds igniter and r/r - this way the r/r gets better "idea" of battery health. Read gs stator health stuff from posplayr. Consider getting a SH-775 r/r to enjoy happy motoring!

[DaveP]

Thanks. I'll take a look at the GS Stator Health info. I had an earlier post, "where does the r/r go?" since it is currently just laying inside the frame from the PO.

Hopefully once I get the carbs and air box back in this will start to make more sense.

[OldVet66]

It needs a solid grounded mount, preferably somewhere it will get free air flow and not splattered with mud. I'm sure plenty of people have done it on your model bike who will chime in.

[chuck hahn]

The electrical panel itself is often very poorly grounded. Many ( including myelf) take a long wire and run it around one of the mount bolts on the R/R and the starter selinoid and back up to the collection point on the battery box bolt. Then a short wire from the battery negative to that bolt makes it all grounded very very well right to the battery itself. I had to get a longer bolt once everything was at the battery box bolt though.

[tom203]

A good "common" ground point on this model is the bolt that holds airfilter box to frame (the lower one at front)- you can easily run ground jumpers to battery negative, ignitor plate,etc. Also this is a good spot to have your R/R ground connected to, no matter what R/R you use.

[DaveP]

Thanks everybody. Hopefully I'll be to this point soon. Just going to bench sync the carburetors before reinstalling.

[jbird7262]

The electrical panel itself is often very poorly grounded. Many ( including myelf) take a long wire and run it around one of the mount bolts on the R/R and the starter selinoid and back up to the collection point on the battery box bolt. Then a short wire from the battery negative to that bolt makes it all grounded very very well right to the battery itself. I had to get a longer bolt once everything was at the battery box bolt though.

Does this type of grounding also work well with the 1980 GS750E?

[OldVet66]

All of the GS series benefits from a single point ground.

[posplayr]

All of the GS series benefits from a single point ground.

This is a drawing I did a while back showing 4 equivalent single point grounding options.

This is showing how ground returns from 3 sources need to get back to R/R(-)
battery return current
Frame return current
Harness return current.



The #4 is more like a Multi point ground, but if you assume all the ring lugs in the two bolt locations and the contact through the metal plate joining is one, then it is Single point.

The main point beyond making sure these ground paths are all in good shape, is to also that there is no sharing of any current other than charging current between the battery(-) and the SSG with SPG as close to the R/R(-) as practical.

If the R/R is right across the battery then all of the current flows between the battery and the R/R giving larger voltage drops.

[DaveP]

Thanks for all of the suggestions on improving the ground connections. At this point I am trying to stay with the original setup until I get the bike running for the first time. Once it is running, then I'll go for the reliability improvements.

I believe I properly connected the R/R to the bottom of the air box and mounted the ground wire as shown in the red circle looking through the battery box. Seemed to be the logical place to connect the ground, but now as seen in my other posts today, the bike is not cranking with the starter button and I don't appear to have spark when the solenoid is jumped.

[tom203]

Solenoid clicks in ( and engine cranks) when jumped , but this doesn't feed the ignition circuit (so no spark). You're not getting power thru kill switch, so you got connection problems. Power runs from main fuse, thru key switch, back thru fuse box up to kill switch and down to ignition system. You need to download and study the wiring diagram off Basscliff's. click thru to get it-make big copy

https://sites.google.com/a/dslextreme.com/cbsaunders/images/1981GS650GLX.Jpg?attredirects=0

[DaveP]

I have printed out the color wiring diagram and b/w version from the manual to make sure the color designations are interpreted properly. Went big, made a 24"x36" of the color version and some 11"x17" for review.

My primary experience is with boats and I did most everything I needed to do with a test light.

I did try the test light this morning quick before heading to work on the yellow/green wire. No light when the starter button is pressed... so definite issue somewhere in the wiring.

Chapter 7 in the service manual details some of the electrical testing for items like the rectifier. Any suggestions on a good quality, not too expensive digital multimeter?

Thanks,
Dave

[tom203]

Multimeter ( digital is best) will cost about $15 . Wallymart,harbor freight,sears,etc. Best to read instruction manual for meter ! You'll be a whiz with it soon,thanks to Suzuki.