what grounds go were? Charging probelm 1981GS850G

[Guest]

My bike has so be jump started, this week, figured dead battery or not charging. Charged battery up over night
at rest 12.15volts
key on lights on 10 sec 11.8volts
idle 1500 rpm 12.5volts
5000rpm 12.01volts

Stator legs unplugged, each leg to each other 90 volts a/c at 5000rpm

removed ground from top of battery box, under rubber isolator, moved directly to battery, no change still not charging at 5000rpm


removed voltage regulator, relocated to top of battery for now, ran ground right to the battery. Now I get 13volts from 2500 rom and at 5000rpm I have 13.8 volts. is that good enough? shouldn't it be 14-15 volts?

Do I just cut off the regulator ground, and lengthen it, to reach the negative post in its stock location? can I leave the ground from the battery box going directly to the battery two? What does that ground do?

[posplayr]

See gs charging health in my signature

[04colyZQ8]

See gs charging health in my signature

I did, I read through it while its very helpful, the pics don't come up for the GS750 you did, and I was quite confused as to were the grounds get rerouted too?

Anyway I wound up moving the factory ground from the solenoid to the R/R, and the battery box ground to the solenoid, I then jumped a 12ga wire from the same screw on the solenoid to the R/R. I kept the factory wire from the motor to the battery. I ran a second wire from a different bolt on the motor 12ga to the R/R. I ran a 6ga wire from the battery to the R/R!! I cleaned the fuse box ground, and fuse box terminals, and cleaned the starter solenoid terminals!

I bench charged the battery
at rest 12.5 volts
idle 12.6volts
2500-3500rpm 14.3 volts
5000rpm 13.98volts
idling high beams on, turn signals going, brake on 12.4-12.6volts
Way better good enough I guess? Would like to see 14-15 volts at 5000rpm, but hey at least its charging now!

All the lights are way brighter, had people flash me, with the high beams on, that has never happened.. The bike cranks over so..darn fast it scared me.... fires up instantly now! The signals, and dash lights all nice and bright!

[Brendan W]

Read back over the charging health again paying particular attention to voltage drops on the supply and return from the r/r to the battery.
The battery negative is not the lowest point of the system. Any bad connections between there and the r/r will raise the voltage at the battery negative.
As you are probably now finding out, 90% of carburettor problems are electrical.

[posplayr]

I did, I read through it while its very helpful, the pics don't come up for the GS750 you did, and I was quite confused as to were the grounds get rerouted too?

Anyway I wound up moving the factory ground from the solenoid to the R/R, and the battery box ground to the solenoid, I then jumped a 12ga wire from the same screw on the solenoid to the R/R. I kept the factory wire from the motor to the battery. I ran a second wire from a different bolt on the motor 12ga to the R/R. I ran a 6ga wire from the battery to the R/R!! I cleaned the fuse box ground, and fuse box terminals, and cleaned the starter solenoid terminals!

I bench charged the battery
at rest 12.5 volts
idle 12.6volts
2500-3500rpm 14.3 volts
5000rpm 13.98volts
idling high beams on, turn signals going, brake on 12.4-12.6volts
Way better good enough I guess? Would like to see 14-15 volts at 5000rpm, but hey at least its charging now!

All the lights are way brighter, had people flash me, with the high beams on, that has never happened.. The bike cranks over so..darn fast it scared me.... fires up instantly now! The signals, and dash lights all nice and bright!

You should not apply the factory manual charging range after changing out the r/r for a series model.
Your charging came up to 14.3 at 2500 rpm, but dropped at higher rpm. If you read the quick test diagnosis again you will see this indicates resistance. Many times it is on the positive lead from battery (+) to r/r (+).
you can confirm using stator pages phase a voltage drop tests.

you are close but dropping about 0.3-0.4v at 5k rpm. You have to chemically clean the contacts.