CB350 voltage regulator check?

Mikey G

Mikey G

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Location
Adrian, Michigan, United States
I'm helping my brother slowly put his '69 CB350 back together, and the first thing we're tackling is the charging system. The bike wouldn't charge a battery when he bought it, and while I checked the stator (plenty of juice coming out of that) and replaced the rectifier (the old one tested bad), he's still only getting about 12.5 volts at the battery while the bike is running and revved to a few thousand RPM. All that's left is the voltage regulator, and that's where my question lies.

Is there any good way to test one of these? I've read about ways of disconnecting it briefly and checking for a voltage spike at the battery, but to do this do you just unplug it? Or are there wires on the harness you need temporarily jump together?

Thanks in advance.

EDIT: Did I put Stator check in the title? I'm an idiot. I meant voltage regulator check.
 
Last edited:
Mikey G said:
I'm helping my brother slowly put his '69 CB350 back together, and the first thing we're tackling is the charging system. The bike wouldn't charge a battery when he bought it, and while I checked the stator (plenty of juice coming out of that) and replaced the rectifier (the old one tested bad), he's still only getting about 12.5 volts at the battery while the bike is running and revved to a few thousand RPM. All that's left is the voltage regulator, and that's where my question lies.

Is there any good way to test one of these? I've read about ways of disconnecting it briefly and checking for a voltage spike at the battery, but to do this do you just unplug it? Or are there wires on the harness you need temporarily jump together?

Thanks in advance.

EDIT: Did I put Stator check in the title? I'm an idiot. I meant voltage regulator check.
Click to expand...
Corrected the title for you.

As EzPete mentions, you should ditch the separate rectifier and regulator for one of these from Sparck Moto

12V Single Phase Regulator/Rectifier - Sparck Moto

Sparck Moto - Modern Gear for your Vintage Ride
www.sparckmoto.com www.sparckmoto.com
 
Mikey G said:
Replacing the unit would be the correct play, but for whatever reason when I mentioned a combined unit my brother wanted to stick with the stock setup.
Click to expand...
If he plans to use the old school flooded lead acid battery then he'll likely be adding water to it pretty regularly because the stock system often goes well beyond 14v even with the regulator, and you should mention to him that rectifiers degrade over the years and can easily become a parasitic draw on the battery too.
 
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