Motorcycle Repair: Electrical problems on 1977 CB550K, regulator rectifier, field coil

Question
After first buying the bike I replaced the battery and got it to run perfectly and decided to ride to work. Half way through the ride the bike wouldn't idle properly. When I went to restart the bike there was virtually no charge on the battery, leading me to believe that the bike isn't giving any charge back to the battery.

I got another battery and still the same problem so I didn't get a bad battery that wouldn't hold the charge. The bike runs perfect after the battery comes straight off the charger.

What electrical parts should I check and possibly change. Do I start with the regulator, the points and condensers, or the stator. Or am I on the wrong track altogether with why I am having these electrical problems.  

Answer
Aaron, you need to start by checking the voltage on the battery when the bike is reved up to 3-4000 rpm.  It should be 13.5-14.5 volts when the battery is fully charged. If it's low, the problem could be the staror, the field coil or the regulator/rectifier.  If you check the resistance between the 3 yellow wires in the stator, they should have equal resistance between each of the three wires and no continuity to ground.  The field coil should have somewhere around 3.5 ohms and no continuity to ground.  There no easy test for the recitfier/ regulator that can be done without special equipment but if the stator and field coils are okay, it's about all that's left.  This assuming all of the connections between, the stator, regulator and battery are clean and tight.  Look for evidence of the wiring harness connectors being hot.  That indicates loose connections and high resistance.  My neighbor's bike just caught fire because a similar loose connection.

Regards
Rich