Motorcycle Repair: ct200 Overcharging?, lighting load, bill silver


Question
Hi Bill -- Thanks a million for your time.  I have recently restored a '66 CT200.  Everything's working and fine, except that while upgrading the rectifier with the Radio Shack unit, as was suggested by several 'CT' sites, I noticed that my system is putting out 8.4 volts @ 3,000 RPM.  Questioning this reading, I put the old rectifier back on for a 'base' check.  It was the same.  Battery is new.  Is this alright, or will it burn my bulbs out? Thanks again!

Answer
Michael,

I had to use the C200 wiring diagram for a reference, although the CT200 should be similar and also like the early CT90s.

http://oldmanhonda.com/MC/WiringDiagrams/MCwiring.php#class

With two different rectifiers doing the same thing, either you have some wiring connection issues or that is the way it is for that charging system. A fully charged 6v battery is really supposed to show about 6.4v on a quality volt meter. The charging systems will send out more than that under full output conditions. Make sure that the "new" battery is fully charged on a charger and that it load-tests okay.

You didn't mention whether the reading was with lights ON or OFF. When the lights are off, you are feeding the rectifier with the two legs of the three coming from the stator. When the lights go ON, then the yellow and white wires are connected together at the ignition switch, sending the extra voltage/current to the rectifier to offset the lighting load. Both readings should be about the same, all things being equal and correctly functioning.

Check your wiring connections in the headlight shell to be sure that all colors match up correctly. All ground connections need to be clean and tight, including the battery and rectifier grounds.

Bill Silver