76 CB750 Voltage drop

[rbattles]

Trying to rework an old 750 but can't get past the electric system. When charging it shows 12.4 volts. Turn the key on and it drops to 11.2 volts. After some testing found the problem goes away if I unplug the generator.

Is this normal or do I have a problem? What tests can I run and what readings should be expected?

NOTE: The bike was in storage for 9 years and previous owner couldn't answer any questions.

 

[Medyo Bastos]

Retest at 1/4 throttle; 1/2 throttle, and full throttle...

 

[amc49]

https://motorcycleproject.com/text/SOHCcharging.html

 

[rbattles]

Retest at 1/4 throttle; 1/2 throttle, and full throttle...

The bike doesn't do anything; trying to get it running. Have replaced most of the electric system as I find defects.