Author Topic: Regulator/Rectifier problem?  (Read 1005 times)

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Offline MauiK3

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Regulator/Rectifier problem?
« on: January 05, 2020, 08:46:23 AM »
My K3 had been running fine but recently I came up with an electrical problem.
1973 CB750 K3
New wiring harness, Hondaman fuse block, fresh battery kept on a battery tender.
When I turn on the ignition the dash lights are dim and it won't turn over.
I was able to jump start it and only saw 6 volts at the battery at high RPM, about 3000.
Won't idle at all, likely due to low voltage.
When shut down, the battery shows 12.4 volts connected or disconnected.
I checked the diodes in the modern regulator/rectifier, they check ok.
I checked the stator, it checks ok. No shorts to ground or each other.
I also noticed that with the ignition on and nothing else being done, the regulator rectifier sings just sitting there, it has a whine. That doesn't seem right.
Any ideas?
1973 CB 750 K3
10/72 build Z1 Kawasaki

Offline SOHC4 Cafe Racer Fan

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Re: Regulator/Rectifier problem?
« Reply #1 on: January 06, 2020, 08:39:00 AM »
Another variable: - what kind of battery are you using?  What type of reg/rec?

Assuming you are using a solid state reg-rec like a Rick's, are you using a lithium-ion battery?  If so, are you using the reg-rec specifically designed (new model 14-100) for use with lithium-ion batteries or the model 10-100?
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Offline MauiK3

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Re: Regulator/Rectifier problem?
« Reply #2 on: January 07, 2020, 07:48:18 AM »
Standard sealed lead acid battery
I got my reg/rect from Yamiya.
I'm going to remove the tank and start backward from the switches to see where I lose half the voltage.
I suppose it may be a burned contact somewhere making a high resistance connection.
The singing rectifier may be a separate thing, I just wonder why it would make such a noise and if it's a problem.
1973 CB 750 K3
10/72 build Z1 Kawasaki