1981 CB750C not charging

[SmashEmUp]

I have a 1981 CB75C (the chassis is a C but the motor and all associated parts were swapped over from an F, not sure if that makes a difference.) and it is not charging. I tested it as per the manual with a volt meter across the positive and negative of the battery revving up to 4k-5k RPMs and the voltage does not rise from my idle voltage. I have already replaced the reg/rec and the stator. I read elsewhere that you should read approximately 4.2 to 5.0 ohms between the sliprings of the rotor. I checked mine and it only measures about 1 ohm. With the stator cover on the bike I measured across the black and white wires and again got about 1 ohm, so I believe that my brushes are good and making sufficient contact. I also measured across the black and white wires with the motor running and I'm getting 12 volts (approx).

My question is would the low ohms of my stator cause my complete lack of charging? Do I have a problem elsewhere?

Any help is appreciated and thank you in advance!

[SmashEmUp]

I forgot to add that I'm not getting any three phase AC out from the three yellow wires on the stator harness.

[icerigger]

The short answer is yes. The rotor needs 4 ohms minimum to generate enough volts to charge. You need a new one.

The bad news is that the rotor usually takes the regulator with it. The regulator works by passing current through the rotor to generate output current. The regulator passes a proportional current into the rotor to maintain sufficient output. If the rotor is shorted out it will never generate enough voltage to charge and the regulator  passes more current to the rotor trying to bring the voltage up until it fries. This doesn't take long, so check your new regulator as well.

[SmashEmUp]

Cool, thanks icerigger. That was my guess but I want an educated, experienced opinion. The bike hasn't been ridden with the new reg/rec installed. Only being ran for testing and troubleshooting. So I hope it wasn't ran long enough to do damage. But I'll be prepared to buy a new one if necessary. On a positive note, I checked the rotor on the donor bike yesterday after work and it measures about 4.3 or 4.4 ohms so I have a free replacement. I just have to get a rear wheel back on it and move it since the stator side is right up against the house. Hopefully I have a serviceable reg/rec. I'm pumped to get this bike ribbon properly since I put it back together from tubs of parts and then swapped everything over to a titled frame. It's been a lot of work but a lot of fun and now that riding weather is becoming more regular, I'm excited to actually ride and enjoy this bike.