78 GS 1000 charging problems

[Anonymous]

I recently bought a 78 gs 1000, runs good but I think the carbs need to be rebuilt. Anyway, the charging system works well, 13.5 volts at 3000 rpms. But as soon as I turn the headlamps on it drops to 12.5 and keeps going down from there, if i turn the headlamps off it slowly rises back to 13.5 volts. It has a Vetter windjammer fareing on it, could this be part of the problem? or just the stator,rectifier or regulator.
Thanks for any info.
Craig

[Hap Call]

Re: 78 GS 1000 charging problems

I recently bought a 78 gs 1000, runs good but I think the carbs need to be rebuilt. Anyway, the charging system works well, 13.5 volts at 3000 rpms. But as soon as I turn the headlamps on it drops to 12.5 and keeps going down from there, if i turn the headlamps off it slowly rises back to 13.5 volts. It has a Vetter windjammer fareing on it, could this be part of the problem? or just the stator,rectifier or regulator.
Thanks for any info.
Craig

My guess is that one leg of either the regulator or rectifier is bad.

Hap

[SqDancerLynn1]

First thing to do is to clean aLL of the connections, solder them together if you can. Then add a ground wire from the reg mounting bolt to the (-) battery cable. Then recheck your readings if they are still bad go to the stator pages in the forum or click on the electrux logo on the links page for the trouble shooting procedures

[saaz]

All of the above.
Make sure all the connections are solid. Make sure the lighting circuit of the stator, which goes through a stupid little switch in the lighting switch, is working. It is flimsy and prone to failure.

78 GS100 here!

[KEITH KRAUSE]

All the above is good advice. 4 years ago I installed the Electrex R/R($110) and added the ground wires and replaced all connectors. No more problems and I've got piece of mind. Best $ I ever spent!

[earlfor]

Re: 78 GS 1000 charging problems

I recently had that same problem with my 1150. To determine if it is the stator or the regulator/rectifier at fault, you can do an easy test. The stator is a three phase unit and each leg should output 80 volts AC at 5000 rpm.
The stator has three output wires. They will usually be yellow, but on some models they are different colors. The color does not matter. All legs are the same. The R/R should have 5 wires, 3 yellow AC input wires, and two DC output wires, usually red and black. Sometimes there will be a 6 th wire that is green and it is an additional ground wire on the DC side.
Disconnect the stator output wires from the regulator/rectifier. Set your multimeter to 200V AC. Start the bike, let it warm up and make all AC voltage measurements with the bike running at 5000 rpm. If we call the leads from the stator A, B, & C, then you want to put the meter test leads between A and B for one leg, A and C for the 2nd leg and B and C for the final leg. If all show 80 volts, then the stator is fine. My stator did output 80 volts @ 5000 rpm and I assumed it was the R/R that was faulty. I replaced the R/R with an electrex and charging is normal now.

The red + and black - DC output wires from my regulator/rectifier are connected directly to battery terminals. If connected this way, an additional casing ground wire on the R/R is not needed.

When someone is having electrical problems causing the bike to run poorly, my first suggestion is to check wiring connections for corrosion, but for a charging problem, I dont think that applies. The charging circuit is immune to excessive resistance and corrosion in the rest of the bike's wiring harness because electricity will always take the path of least resistance.
The charging circuit consists of the stator, regulator/rectifier and battery.
If the R/R's DC red+ and black- wires are connected directly to the battery terminals, that will always be the path of least resistance and the R/R will only be concerned with battery voltage (electrical pressure) Even a direct short in the bike's lighting system will not alter the maximum possible charging voltage from the R/R as it is limited to a max of 14.9 regardless of the draw (if working correctly). In the instance of a short, you would still have an output from the R/R of 14.5 +, (due to brands and individual units, max output can vary) but there would be no wattage (flow) left to charge the battery. The charging system would function normally.

To verify this, you can disconnect the red and black wires between your R/R and the bike's battery and connect those wires to a spare battery on your bench. Leave the original battery in the bike hooked up. This isolates the charging system from the bike. Start the bike and do the same tests of R/R output. If the voltage level of the spare battery (electrical pressure) is the same as the voltage level of the battery in the bike, then the charge rate will be unchanged. The R/R adjusts to draw to maintain a constant voltage, so electrical draw from the bike will not change the R/R output. Charging voltage will be the same regardles of whether the headlight is on, off, on high or low or only the ignition running.


This was quite a bit longer than I had intended, but I thought that an explanation of why and what would make it easier to trouble shoot the problem than just a list of values to check. If you know what is happening and why youre doing something, its always much easier to fix it. :-)

Earl

I recently bought a 78 gs 1000, runs good but I think the carbs need to be rebuilt. Anyway, the charging system works well, 13.5 volts at 3000 rpms. But as soon as I turn the headlamps on it drops to 12.5 and keeps going down from there, if i turn the headlamps off it slowly rises back to 13.5 volts. It has a Vetter windjammer fareing on it, could this be part of the problem? or just the stator,rectifier or regulator.
Thanks for any info.
Craig

[gremlin]

All of the above.
Make sure all the connections are solid. Make sure the lighting circuit of the stator, which goes through a stupid little switch in the lighting switch, is working. It is flimsy and prone to failure.

78 GS100 here!

get a wireing diagram and remove the head light and switch from the charging circuit.

it will drive you nuts with that fairing.

[KEITH KRAUSE]

Earl, long replies are sometimes necessary to try to help people understand and fix their problem. I always welcome as much info as possible. Longer replies tell me the person wants to help and is taking the extra time. If someone gets bored and stops reading half way through, then that's their loss.
Members like you make this a great site!

[Anonymous]

Thanks to everyone. I am a mechanic by trade but this problem is driving me nuts.
Earl:
The 78 has a seperate regulator and rectifier. Im at work now and dont have my schematic with me, are the wireing colors the same?
we just had a cold front move through, its 0 degrees out, and i dont have a heater in the garage so it might be a little while till i get out and make these checks.
Ill keep you posted though

Thanks again

[earlfor]

The wiring colors for 1978 models with separate regulator and rectifier should be: The three stator AC output wires 1. yellow, 2. green/white,
3. blue/white. The yellow AC stator output wire will be plugged into a "Y" connector. Two leads exit that connector....... (they should all be yellow) one exiting lead goes to the regulator, the other lead goes to the rectifier.
The blue/white AC stator output lead connects to the blue/white lead on the rectifier. The green/white AC stator output lead is connected to a plug in your wiring harness which leads to the lighting switch on the left handlebar. The RED DC output wire on the rectifier connects to a red wire that is spliced into + power feed line between your 15 amp fuse in the fuse block and your ignition switch. The regulator will have either a green wire, a black wire, or a bolt contacting the regulator case which provides ground to the regulator.

Just check as I said earlier that the AC voltage from your stator is 80 volts at 5000 rpm. If it is, then you need a new R/R. The one you probably need is Electrex R/R10. My opinion is that you can get a R/R to fit your bike for a bit less money than an Electrex costs, but you cant get a better one for any amount of money. :-) I know from experience that if the R/R decides to "take a dump", the bike will run for about 30 minutes before draining the battery and then youre done. I didnt enjoy those 25 mile long walks much at all. :-) I went for the best R/R I could get. heh heh


The Electrex R/R's will have three yellow (AC input) and DC side two wires, red + and black -. Wiring connections would be your stator output
yellow wire to yellow on R/R, stator blue/white to yellow on R/R, stator green/white to yellow on R/R. R/R DC output red wire to battery positive terminal.
R/R DC output black wire to battery negative terminal.

You can cap off the previously used green/white wire that leads to your lighting switch. The original lighting switch configuration is dual powered and you will now only be using the DC power side of it. (that has not been altered)

The original red lead in the harness that spliced into ignition power feed is also no longer used. Cap that off too.

By running your new rectifier red and black DC leads directly to battery terminal, there is no point in adding additional ground wires to the the rectifier case. In fact, I have mounted my rectifer on a plastic board with rubber feet between it and the board to allow airflow on all sides of the rectifier. The plastic board and rubber feet also help to cancel any vibration to the rectifier.

Earl

Thanks to everyone. I am a mechanic by trade but this problem is driving me nuts.
Earl:
The 78 has a seperate regulator and rectifier. Im at work now and dont have my schematic with me, are the wireing colors the same?
we just had a cold front move through, its 0 degrees out, and i dont have a heater in the garage so it might be a little while till i get out and make these checks.
Ill keep you posted though

Thanks again

[earlfor]

Thanks Keith

Earl :-)

Earl, long replies are sometimes necessary to try to help people understand and fix their problem. I always welcome as much info as possible. Longer replies tell me the person wants to help and is taking the extra time. If someone gets bored and stops reading half way through, then that's their loss.
Members like you make this a great site!

[gremlin]

a very quick and durty way to test the stator, to see if its burnt out. get a county tester one that beeps, put one clip on the motor, disconnect the stator and probe each wire. if you hear a beep your stator is fryed.

most of the time a stator will cook or burn a wire on the stator and short to ground thur the oil.

[Anonymous]

GS1000 Charging

Craig,
I was having charging problems with my 78 GS1000 and thought my stator was bad (maybe it still is). I checked the stator A/C voltage and it was giving about 18 volts. So....it must be the stator. I removed the stator intending to rewind it myself. I took it into an electric motor shop to get some wire to rewind it and the technician said that it looked in perfect shape. He checked it with an ohm meter and said it was OK, must be the regulator/rectifier. I had a cheap digital VOM meter from radio shack & checked the regulator diodes and found that they were bad. So, I bought an Electrex R/R. Now my bike is acting just like yours. Everything works great till I turn on the headlight. All the voltages are perfect when the headlight is out.

What was the resolution to your problem?? Any help would be appreciated.
Thanks,
Frank

[mcycle-nut]

If your regulator OR rectifier is fried, gas the both of them and install a reg/rec from a Honda CM/CB 400 twin. Hell, there are some threaded bolt holes on the bottom of your battery box that line right up to holes in the Honda unit! At least there are on my '78 GS750. 8)

[Anonymous]

GS1000 charging problems.

Get a honda superdream 250 reg / rec and wire it up as follows:-

Honda three yellow wires go to Suzuki Yellow, red/white, and blue /white.

Honda green goes to earth ( do yourself a favour and extend it and run it to the battery negative ).

Honda red to Suzuki red.

Honda black to Suzuki orange ( this is additional power output connect it to the rear brake light switch).