CL77 charging issue

[sparks454]

Working on a '65 cl77 resto project. Finally got it running and driving before we tear it down to rebuild, but the charging system appears to not be working. One stupid question, we don't have the headlight in place. Does the bike need this connected to charge the battery? If not, wondering if the rectifier is not bad.
Did a search here for charging system and came back with many documents that did not have what I was looking for. Can someone point me in the right direction. Thanks,Chris.

[Wilf]

Chris,

Have you measured the voltage at the battery terminals when the engine is running (at more than idle speed) and also not running? It should be around 6.2 volts with the ignition off, and something over 7 volts when running.

Wilf

[sparks454]

Is this not a 12V system? My dad bought and put a 12V battery in there. Voltage on the battery while at idle or not, only shows a change of about .2V.

[Wilf]

Duh! Yes it's a 12 volt system. I was think of a charging problem on a previous machine. Voltages should be more like 12.6 and 13.8.

The charging voltage at idle is not going to be very high--this is an AC generator, so the output voltage is going to be rpm dependent.

Wilf

[sparks454]

I agree about the voltages. There really is no change when RPM's change. Never owned a honda this old though, so I wasn't sure what may be preventing it charging. I have an old Norton and some newer Hondas though. Looks like we might be replacing/upgrading the charging system then. I just thought that maybe the rectifier may be bad. Thanks.

[Wilf]

The rectifier, especially if it's the original selenium stack, could be bad. Or there may be resistance (corrosion, poor connections) in the charging circuit. I've replaced my selenium rectifier with a silicon bridge because they're more efficient, are less likely to leak and should last forever without degrading.

Wilf

[sparks454]

Thanks for the input Wilf. Quick way to test the rectifier? Ohm it out maybe..