Author Topic: 74 cb500 will not stay charged  (Read 622 times)

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Offline illessteve500

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74 cb500 will not stay charged
« on: October 02, 2014, 08:19:09 AM »
Just got back on the site...love this site need to start on the project again...so heres where i left off got a 73 cb500 have some charging problems...took it out for the first on a full charge and drove for about an hour and bike died battery was fully drained let the bike sit and was able to get it home pretty much blasted it home... the set up i have is just dyna coils 7mm copper core wires and a combo reg/rec i had someone wire this bike for me he is used to wiring 750's supposly he said the 3 yellow wires are hooked up differently on the 500's one of the yellow wires has to be hooked up a certain way how true is this..any ideas would help me out at this point also he said the charging system doesnt kick on and start charging untill 5000 rpms how true is that seems alittle high to me..thanks for the help.

Offline willis

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Re: 74 cb500 will not stay charged
« Reply #1 on: November 04, 2014, 10:32:19 PM »
Might be a very weak battery. Or something else could be sucking current. I would see if there is any current draw while the system is off. Grab a multimeter and put it inline with the batter while the bike is off and see if there is any current draw.

Offline dave500

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Re: 74 cb500 will not stay charged
« Reply #2 on: November 04, 2014, 11:26:17 PM »
if its not charging till 5000 rpms that's wrong,mine charges at idle I don't know where everyone gets crappy charging at low rpm from?
« Last Edit: November 04, 2014, 11:30:05 PM by dave500 »

Offline TwoTired

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Re: 74 cb500 will not stay charged
« Reply #3 on: November 05, 2014, 11:25:43 AM »
the set up i have is just dyna coils
3 ohm or 5 ohm?  It matters to power draw.

i had someone wire this bike for me he is used to wiring 750's supposly he said the 3 yellow wires are hooked up differently on the 500's one of the yellow wires has to be hooked up a certain way how true is this..
You want us to troubleshoot an electrical circuit with out a valid wiring/connection diagram?
This is akin to riding to motoring about in the Brazilian rain forest with no road or path map and no compass.  Want to be a happy wander!
BTW, whoever did your wiring hasn't a clue how the CB500 charging system is supposed to work.
We are familiar with the known working stock arrangement.  "Custom" situations require definition in order to get a definitive answer regarding operation or correction.   We can help, but you will still need to do the required work.

he said the charging system doesnt kick on and start charging untill 5000 rpms how true is that seems alittle high to me..thanks for the help.
Seems like more proof you placed your trust in the wrong hands.
Depending on the electrical loads placed upon the alternator, it may not charge below 2000 RPM.   But, we don't know what you bike's current load or electrical draw is.  The Cb500 Alternator should have at least a 12 Amp output at 5000 RPM.  The slower turning speed at idle is less than peak output, averaging about 1/3 of max or about 5 amps.  The alternator can never make more than capability.  So, if the bike's electrical draws 12 amps, don't expect the battery to ever charge.
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline Vinhead1957

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Re: 74 cb500 will not stay charged
« Reply #4 on: November 05, 2014, 11:51:51 AM »
There is a trouble shooting guide in the faqs section.