Gs 1000l

[marty2468]

gs 550 very fast

[chef1366]

Check out the stator papers

[posplayr]

No expert

But I did just totally went through a crash course on the electrics on my 1981 GS750EX. As you may know there are three charging legs on your stator (under the left hand cover). On typical (non-GS) configurations all three stator outputs are inputs to a shunt rectifier/regulator which takes the stator AC and rectifies it (DC with ripple) and directs current to ground to control the output voltage of the charging system. The higher the output load is the less current the regulator has to shunt to ground (and visa versa).

Now these GS bikes did not start out like with the benefit of a particular well designed R/R and infact there is a major bandaid as a stop gap measure to avoid over stressing the R/R. The 3rd leg of the stator is normally open when the lights are off. The eases the amount of current the R/R might have to shunt as it is only dealing with two legs of the stator when the lights are off.

When the light go on, the third leg is utilized (it is wired in series with the headlamps) then the R/R has to deal with all three, but since the head light represents such a large load, there may infact be a drop in the total current shunting being required of the R/R. Given the apparent poor design of the R/R (poor efficincy that requires this type of aiding), the configuration is probaly more stable than having all three legs active all the time.

All of the discussion is to provide background to exlain what you are probably seeing going on. It sound like one of your stator legs is not charging, or the cooresponding R/R input is open circuited. The stator leg that is not charging in also not connected through the light switch. When you put the light on you at least have two of the three charging which is enough to get you up to 13.2V (which is still low).

You should verify that you are getting output on all legs of the stator and if that is happening then you probably have a bad R/R where one of the inputs is open, and not rectifying the AC input to add to the avaliable charging power.

You should most definitely follow the stator diagnosis chart in the "Garage" section at

http://www.thegsresources.com/garage/gs_statorfault.htm

Even if you solve your obvious problem, you need to get the voltage differences between the R/R ground and output as close as possible to the battery levels when at 4000 RPM. It is very easy to have bad connectons that at idle amount to 0.1-0.2 volts that go to 0.5-0.6 volts and will cause you to over charge your battery.

Bottom line just follow the diagnosis chart and replace the stator or R/R or both depending on what you find.

Posplayr

[gsgeezer]

Years back when I got the GS1000, I had to replace the starter clutch. I read all the stuff in the old Q&A and decided to go with the Electrex system. Never had any problems.
(In the eighties I had an 850 and I never had any trouble with that, but I guess I was lucky!)

[DanTheMan]

I just purchased this 1979 GS1000L and I seem to have a problem with my charging system.With the bike off or running at 2500RPM I show 12.5V
but if I turn the headlight on (yes this bike has an off switch for the headlight)at 2500rpm it bumps up to 13.2v any ideas
Thanks Marty

Actually, 13.2V doesn't damage a thing. Most charging systems in order to maintain proper battery level charge between 13 and 14.1 volts. I don't think you have a problem. I installed a permanent voltmeter on my bike, (headlight is always on), and when I'm running down the road at 2500 RPM or better, unless something is wrong, it's always charging close to 14 volts. That's normal.:-D

[posplayr]

This is a problem

>>>>With the bike off or running at 2500RPM I show 12.5V

Something is broke ; there is no charging with the lights off!!

If two legs of the stator are not working (either because of the stator or the R/R) then the last leg of the charging system is likely living on borrowed time as well.

Changing out the R/R maybe the solution, the stator might also be. But even with both there could be connection/grounding issues that caused the problem in the first place(i.e. see stator diagnosis diagram).

Posplayr

[Matchless]

OK, just a temporary fix. It sounds as if your bike may still have the 3rd charging phase switched into circuit on the light switch when you put the lights on. Onn later bikes the switch was bypassed by bridging the orange/white and green/white wires. You can do this easily yourself:

Assuming all is still original:
Locate the 3 wires, green/white, blue/white, yellow coming from the stator.
Now locate the rectifier/regulator wires orange/white, blue/white and yellow

1) The yellow from the regulator should be plugged into the yellow from the stator
2) The blue/white form the regulator should be plugged into the blue/white from the stator
3) The orange/white from the regulator is plugged into an orange/white wire that runs to the front of the bike - unplug this one
4) The green/white wire from the stator is plugged into a green/white wire running to the front of the bike - unplug this one
5) Now plug the green/white from the stator into the orange/white from the regulator

This should keep the 3rd charging phase in circuit regardless whether the lights are on or off and is the way all those bikes have been modified. Now you should get some charging with lights off as well if nothing else is wrong.

Still check out all 3 phases for AC voltage and your regulator as it seems as if one or both of the other phases may not be working - Or if you are lucky it is just a bad earth or a bad connection. The stator papers and many other posts in this forum should help you if so.