Kent hit the nail on the head. You have used a very good tool to troubleshoot the health of your charging system but the charging system is made up of the regulator/rectifer, battery and stator (aka alternator). Now you need to jump into the troubleshooting guide and determine WHICH component is the issue. Before tackling the steps, I strongly suggest you CHECK YOUR BATTERY with a hydrometer. They sell cheap ones at all autoparts stores for about $2. You essentially will be checking for bad cells in the battery and even a new battery can have dead cells. Second, I would CHECK connections. MOST electrical problems on an older bike are in bad connections. The cable from the battery to the engine or frame ground... IT MUST BE CLEAN AND TIGHT. The short cable from your battery to starter solenoid must be clean and tight. Find the wires coming from your stator and plug in either to a junction box mounted on the battery box or perhaps directly into a connector. There will be probably 5 pins (wires) on this connector. Take the connector loose and CLEAN the pins and female sockets with contact cleaner and coat the pins with dielectic grease. Do the same for the connector coming off your regulator and rectifier (or reg/rec as some are combo units). Once you have done this minor stuff, MOST charging problems seem to disappear. If they don't then start looking at component failure as Kent suggested. If you have a bad connection, the tests he suggested will point (FALSELY) to replacing stuff that might just be OK... just not plugged in good. And if the battery has a bad cell, you will go nuts testing other components as the tests assume the battery is peachy fine!
