Author Topic: '78 CB750F, volts at the battery low  (Read 1024 times)

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Offline SurfinBird

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'78 CB750F, volts at the battery low
« on: February 09, 2014, 04:08:39 PM »
I put in a new battery and replaced my regulator with a stock used one. Getting only 12.45 at the battery at 3000 rpm and about 12.8 at 5000. Any suggestions on where to go from here? I really clueless on electrical.

Offline Jerry Rxman Griffin aka MuthaF'er

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Re: '78 CB750F, volts at the battery low
« Reply #1 on: February 09, 2014, 05:07:41 PM »
Uh oh, here we go again. Hardware = regulator, rectifier, stator, field coil,

Let's say it's not the regulator (but could be). Check the rectifier. Voltage should go through on 3 sets of diodes and stopped on the other 3. That eliminates the A of the A/C creating DC. Check the values on the coil and stator.

So if those are good check the input and output voltage on your ignition switch. Once you've done that then inspect, clean, dielectric grease, tighten and reinstall EVERY connector! Yeah, no #$%*, EVERY connector.

Standard Operating Procedures. The usual suspects and usual it is on these old girls.

Yeah, your ground could be loose/corroded. Yeah you could have a short. Yeah you could have a bad wire.

Few questions: Do you have any extra loads like H4 bulb or 3 ohm coils? These things suck more juice.

This PROBABLY won't be fun but.... you've just been hit by the SOHC4 curse. But hey, at least keep your rpms up to keep the voltage up to minimum. Unplug your headlight fuse if necessary and keep your Battery Tender plugged in. Stay away from stop and go traffic too.

OK, time for the other guys' ideas.....

 
As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)

Offline SurfinBird

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Re: '78 CB750F, volts at the battery low
« Reply #2 on: February 09, 2014, 06:25:22 PM »
Thanks Mutha. A little background, I fried the last (gel) battery. I was getting too many volts at the battery. I adjusted the reg to where it should be, but it didn't stay, it dropped too the problem I'm having now. I heard it was better to just swap out the reg instead of trying to adjust. Did that and got a brand new standard battery. The charging system is stock with no mods.