Author Topic: CB750 K4 not Charging  (Read 812 times)

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Offline coolmaven

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CB750 K4 not Charging
« on: April 29, 2013, 06:56:28 PM »

Got my bike all back together and fired up after its cafe conversion and realized its not charging.
So far...
1. New Battery
2. New wire harness
3. New Rectifier/Regulator Combo
4. All connections either replaced or, cleaned
5. Stator tested (cross yellow wires with meter and to ground) - okay

Are there any other tests I can perform to narrow down the problem? Can the alternator Rotor be tested?

Any help would be greatly appreciated.


Build pics...
https://plus.google.com/photos/100693224865817779685/albums/5614879262947603153

Offline wowbagger

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Re: CB750 K4 not Charging
« Reply #1 on: April 29, 2013, 07:21:30 PM »
Not sure if you've seen this already but I cam across it in another forum thread:

http://www.electrosport.com/media/pdf/fault-finding-diagram.pdf

Looks to be a pretty thorough test procedure for checking a bike's charging system.

Offline coolmaven

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Re: CB750 K4 not Charging
« Reply #2 on: April 29, 2013, 07:56:13 PM »
Not sure if you've seen this already but I cam across it in another forum thread:

http://www.electrosport.com/media/pdf/fault-finding-diagram.pdf

Looks to be a pretty thorough test procedure for checking a bike's charging system.

Very helpful... i'll give it a try and report back! thx

Offline Jerry Rxman Griffin aka MuthaF'er

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Re: CB750 K4 not Charging
« Reply #3 on: April 30, 2013, 11:42:59 AM »
Tap the rotor with a hammer and if it goes 'ding' it works. Just a big chunk of metal. Make sure its tight and not spinning freely. Field coil ok?
As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)

Offline Vinhead1957

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Re: CB750 K4 not Charging
« Reply #4 on: April 30, 2013, 02:13:58 PM »
Are you left with a green wire that came off the regulator with that combo?

I have the same problem and I'm thinking that leftover wire should be ground. The field coil green should be ground from the schematic. Check continuity from the field green to ground.   Other applications talk about putting a better ground to the battery
Box this may be a good option too adding grounds will only help things

Offline coolmaven

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Re: CB750 K4 not Charging
« Reply #5 on: May 02, 2013, 03:36:49 PM »
Turned out to be a broken wire from the field coil.

charging away!
Thanks