Need help bad, I have a 1979 CB 750 in Great to Excellent condition, Bike is very clean and not neglected,. Big problem is it wont charge, I already replaced the Regulator, Battery, Stator and the 2 brushes, still when the bike is running it will not increase the voltage to the battery, I also checked all plugs for corrosion or burnt terminals. Any help would be greatly appreciated. John
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1979 CB750 wont charge
- Thread starter cbtdc
- Start date
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- Tags
- electrical
amc49
CB750 Guru
The rotor is the issue 9 times out of 10 on those. And they can be bad and test as good all day long.
amc49
CB750 Guru
You already technically have tested, it's not charging.
Read the output on the three yellow wires going to regulator, they are the a/c output.
And yes bad new rotors have been possible. Especially if gotten off ebay. People sell bad ones claiming they are new all day long. It's one of the early DOHCs' greatest flaws. Mine failed on brand new bike at 3k miles back in '80. I put a total of 3 on it during its' life.
Bear in mind if connectors are taken apart enough the pins may not make contact and that has nothing to do with corrosion or burned.
Read the output on the three yellow wires going to regulator, they are the a/c output.
And yes bad new rotors have been possible. Especially if gotten off ebay. People sell bad ones claiming they are new all day long. It's one of the early DOHCs' greatest flaws. Mine failed on brand new bike at 3k miles back in '80. I put a total of 3 on it during its' life.
Bear in mind if connectors are taken apart enough the pins may not make contact and that has nothing to do with corrosion or burned.
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amc49
CB750 Guru
You already technically have tested, it's not charging.
Read the output on the three yellow wires going to regulator, they are the a/c output.
And yes bad new rotors have been possible. Especially if gotten off ebay. People sell bad ones claiming they are new all day long.
http://www.cb750c.com/publicdocs/charging_system/genesound_charging_system.html
Go to that site (cb750c.com) and join for free and enough stuff there to choke you including the full Honda service manual.
Read the output on the three yellow wires going to regulator, they are the a/c output.
And yes bad new rotors have been possible. Especially if gotten off ebay. People sell bad ones claiming they are new all day long.
http://www.cb750c.com/publicdocs/charging_system/genesound_charging_system.html
Go to that site (cb750c.com) and join for free and enough stuff there to choke you including the full Honda service manual.
Well I swapped out the rotor and stator and still cant read any voltage coming off the yellow wires from the stator. Just wondering to ck ac voltage coming from the stator, should i test with multi meter set to AC voltage, test across the 3 yellow wires or yellow wire to ground. I'm at a loss what the problem is.
amc49
CB750 Guru
Test across each yellow wire to a ground and engine running. Yes, use a/c range. You must have d/c power going into rotor and out with no shorts to ground or opens, or you will not have anything at the yellows. The rotor which is normally not magnetic becomes magnetic when running with a proper working rotor.
