Motorcycle Repair: 1980 honda cb650c not charging, regulator rectifier, resistance values

Question
I got this bike a year ago and cant keep it running.  I found a short that was draining the battery and fixed it.  I also replaced the stator but bike still wont charge the battery to keep it running. That battery doesn't drain fast like it did before and when i rev the engine the volts go up a little then start to drop again.  I'm out of ideas and would be gratefull for any help.

Answer
Daniel,  If you put a NEW stator on the bike then we'll pass by that item, which is the most common cause of non-charging on these bikes. If you put a used stator on the bike, check the brush slip rings to see what the resistance values are COLD and then HOT. They tend to go open or into high resistance when they get good and warm.

Here is a link to a troubleshooting chart, which will help you find the problem:

http://www.elefantadventurebikes.com/electrical_fault_finding.pdf
or
https://www.electrosport.com/electrosport_fault_finding.html
same chart...

If the charging system is trying to charge and then tapering off, the regulator rectifier is probably the source of your current problems. If the rectifier portion shorts out, the diodes can drain the battery, plus that segment of the charging system is not functioning.

https://www.electrosport.com/electrosport_electrical_honda2.html offers parts at far lower prices than Honda.

Bill Silver