Re: Electrical Problem(s)
OK, something is broke.

The charging system is comprised of the stator, regulator/rectifier, and the battery. The stator outputs AC voltage.
The R/R rectifies that to 12-14.8 volts DC to charge the battery. The bike runs on DC voltage, so in essence, it runs completely off the battery always. You have a burned connector on one leg of the stator that connects to a AC input yellow wire on your R/R. It is likely that the R/R on that phase of conversion of AC to DC is faulty and shunting to ground. The wire would consequently be burned. The question is has the added resistance and heat causing the burning been enough to destroy one leg of the stator. I expect your R/R is faulty, but that may not be all of the problem. The only way I know to positively fix this is to check every part of the system.
The first thing you must have is a good, charged battery. A charging system cannot work if it has no place to put a charge. Remove the battery from the bike and put it on a charger (fill to the line for electrolyte level with water.........never add more acid) Charge at 2 amps until the voltage in the battery measures at least 13 volts. Sit the battery aside for 8 to 12 hours and recheck voltage. If voltage has dropped below 12.8, you need a new battery.
Once the battery is OK (new or holding a charge) you can check the stator. (if you have installed a new battery, charge it to a minimum of 13 volts before installing it in the bike. A new battery will take about 8 hours at a 2 amp rate on an automatic charger. Prior to that time, a meter will show a surface charge and not be indicative of actual deep charge.
Install the charged battery. Check and clean both ends of the negative ground cable on the battery. One end is on the battery neg terminal, the other end connects to a bolt on top of the transmission. Temove that bolt and clean the ring connector.
Set your multimeter to the AC scale 200 (AC scale) There are three yellow wires coming from your stator and ending in a plug. Disconnect that plug. The test is done with the plug disconnected. AC voltage has no polarity, so it will not matter which color meter lead you place on which wire of the three yellow. If we number the wires 1,2, and 3, the you want to place the meter leads on 1 and 2 for one phase, on 1 and 3 for the 2nd phase and on 2 and 3 for the third phase of the stator. Each phase should show 80 volts at an engine rpm of 5000. Anything over about 65 volts should be enough to keep the battery charged. All phases should read close to the same value. Start the bike, run it to 5k rpm and check voltages on the pairs of wires I stated. Do NOT let the bare ends of the three yellow wires touch/ ground to anything and not to each other.
Assuming your stator checks within values above, plug the stator back into the R/R. On your R/R, there is a black wire and a red wire. The black is 12v DC negative output and should be connected to your battery negative terminal. If it is not now wired that way, change it. The red R/R wire is 12v DC positive output and should be wired directly to the battery positive terminal.
If it is not, change it so it is. Any other wires the red may have been connected to will now be capped off/taped off and no longer used.
Set your multimeter to the DC20 volt scale. Connect the meter to the battery terminals. (red +, black -) Start the bike and run it to 5k rpm.
voltage at the terminals should be between 14 and 14.8 volts. Probably will be about 14.5 or so. If voltage is within this range, the R/R is fine.
Each step above must be correct before you can proceed to the next.
I would not run the bike with the R/R connected to the stator until the problem has been determined as doing so may toast the stator (assuming it is not already toasted)
Lemme know what you get. If I miss getting back, pm me if you wish.
Earl
chester said:
I have an '81 GS850L with about 12,000 miles on her. My battery is not getting charged. I now have a new, freshly charged battery. She reads 12.75vdc when not running and drops to 11.83vdc while running. This number increases very slightly when I rev the engine, never to exceed 12.0 volts. I used the stator papers flow chart to diagnose the problem and was only able to get to the second test, before becoming confused. When I connect the black lead of my multimeter to the battery(+) and the red multimeter lead to the RED output wire of the RR, the multitmeter reads -0.2v. My leads are connected correctly into the multimeter. I am confused as to why I would get a negative reading? Also, I noticed one of the connectors for one of the yellow wires (actually white with a red stripe) showed signs of being burnt. When the bike idles and I have the low headlight beam on, she flickers a bit. As I rev up the engine...the light goes dim just under 2000 rpm. Above that (rpm) it is good and bright. The high beam appears to work normally, no flickering, no dimming. Should I just go ahead and replace the RR? Any help is greatly appreciated! Thanks in advance!