78 kz650 charging issue - someone please confirm

so im building a 78 kz650 bobber and had to make my own harness before i could even begin to get the bike to run. now i am having issues with it not charging. I am an ASE certified master mechanic with 8 years shop experience and do tons of custom fabrication, electronics, and wiring so please dont just start saying my harness is at fault. everything else works perfect but with that said im also not perfect and it may be the way i wired so if you legitimately have a reason to suspect my wiring please say so and why. ill give as much info as possible.

I hooked the two yellow wires coming off the generator to the two yellow wired coming off the regulator/rectifier
black/yellow wire from reg./rec. is going to ground
white/red wire from reg./rec. is going to a switched battery power. (put it to switched power cause found it was staying hot, in temperature, and killing the battery.)

with a meter on the yellow wires i have 20-28 ac volts at idle (no one with me to rev up)
suspected bad ground so i put my meter on the battery and found the when i jump the ground, even straight to the battery ground, the voltage goes down like the reg./rec. is actually pulling power away. unjump and battery voltages rises back up and levels out again.
even tried to swap the two yellow wires thinking maybe i wired them backwards and there was an issues with a diode direction but that didnt change anything.

here is a video of the voltage dropping when i ground it and coming back up when i take it off. sorry wiring is still in mock up and not the cleaning and the bike hasnt been tuned yet. if you dont care to see it starting jump to 45 sec.


I suspect a bad reg./rec. can anyone confirm or deny? also if you agree with my idea and know someone with a good used one for sale please direct me to them as i am currently buying a house and money is tight but i want this bike done before riding season is over

also i found a regulator/rectifier for a kz650h (which is a 6 wire model) would it be possible to wire it in and only use two of the generator wires instead of all three going to the regulator?

Here's my listings for stators & regulators/rectifiers:

Stators, Regulators & Rectifiers
www.rmstator.com
www.electrosport.com (they have a good troubleshooting page)
www.customrewind.com
www.regulatorrectifier.com
www.ricksmotorsportselectrics.com
www.oregonmotorcycleparts.com (not sure they have stators)
www.accel-motorcycle.com/
www.tpe-usa.com/ (Tim Parrott Enterprises)

Have you been to www.kz650.info for help? If it were me, I'd check the output of the alternator to see if the A.C. output is there before buying a new regulator/rectifier.

Have you been to www.kz650.info for help? If it were me, I'd check the output of the alternator to see if the A.C. output is there before buying a new regulator/rectifier.

with a meter on the yellow wires i have 20-28 ac volts at idle (no one with me to rev up)

ive been to all those sites i dont want to buy a new one at this time. money has is tight right now and i dont have $100+ to spend on it. especially since the only thing ive paid over $100 up to this point is the tubing to make the hard tail.

You have a Single Phase Alternator, 2 wires from stator. You must rev the motor to 4K RPM to test AC output. Get out some clips and leads and hook up your meter so you can Rev the motor and watch the tach and DVOM, simple.
Sounds like the regulator would be wired correctly as black/ yellow is where it shunts excess voltage to ground, red/ white is for B+ both charge and voltage sense, yellows are in coming AC from stator.
Since you have "Switched" the red/white wire because of battery drain, sounds like you could have faulty diodes in the regulator. There are tests for that in the Factory Service Manual. There are links on this site that will be for a manual that has a single phase system.
The other 6 wire Regulator is for the 3 phase alternator, and I have seen posts for using it with the single phase but have not done it myself. I would do a search for both a Manual and Single Phase Charging to get more info.
Also those web sites MFOLKS posted have both stator and regulator trouble shooting.
Start with getting like 70-75 VAC from your 2 stator yellow wires @ 4K RPM.

Yea I didn't havE any leads at the time. I'm going to take home my insulated jumpers today and check it again at 4k and I'll post results

heres two pics i took today of the generator output at 4k RPM. about 70 VAC at 4k rpm

Stator output looks OK to me. Did you find the tests for your Regulator in the FSM=Factory Service Manual? Looks like you had the wiring, other than the switched 12v on red/ white, correct. The red/ white should be straight to Batt +, which you said caused a drain. Suspect diodes in rectifier.

There are a couple of tests I am aware of for the single phase regulator/rectifier. Disconnect the 3 wire (2 yellows and one black) connector from the reg / rec. Measure resistance between each of the yellow leads and the black lead. Use + on yellow and - on black. The value should be less than 20 ohms. Then reverse the test leads (+ to black and - to yellow). The value should be more than 100 ohms. If any 2 leads are too high or too low the unit should be replaced.

You can also check to see if the unit is diverting current to ground as it is supposed to. Connect a voltmeter to the battery terminals. Start engine and let idle, increase speed until voltage going to the battery reaches 14 - 15 volts. At this point, the regulator is supposed to divert the current to ground. If voltage continues to rise instead, then the unit should be replaced.