New Reg/Rec questions

Hi everyone,

1981 Cb750c completely custom build with an m-unit blue, etc...
Bike runs great except the fact that the reg/rec isn't wired in properly. I understand that red/white wire is positive and the green wire is negative but what should the black wire connect to?

I connected the black wire to the m-unit aux port and when I start up the bike the m-unit registers that the port is using 2amps. Am I doing this right and is this drain normal?
Thanks in advance for your help

On the R/R, the black wire is the voltage sensing wire that the regulator uses to determine the strength of the the field coil inside the alternator. It also provides the power for the field coil. If everything is working properly, you should see the load on the m-unit decrease as RPMs of the engine increase. I suspect everything is working as intended.