I'm looking at the charging troubleshooting guide by Rick Jones, owner of Motorrad Elektrik .
The test of the diode board requires removing the assembly from the bike .
Remove the ground wire from the battery .
The test for the diodes, is, put one lead from the meter on the B+ terminal on the diode board, next place the other meter lead on the AC input terminals, these appear in the picture, to be located in the gap between the metal parts the diodes are pressed into, and are parallel to the opening between the metal parts .
If the diode is good, it should have 'continuity ' in one direction , and an 'open' in the reverse direction .
So, if you put the red lead on the B+ terminal all of the diodes should have either low ohms, usually less than 10 ohms, or they should all be open, or ifninite resistance .
When you reverse the leads, put the black lead on B+, and then check the diode terminals, it show the opposite of your first reading .
The second test is to use the D+ terminal, and the previously used diode terminals, and perform the same test, the results should be the same if the board is good, all three diodes show low resistance in one direction, and open or infinite resistance in the opposite direction .
Hope this may have helped you, more than it may have confused you .
From the manual, it doesn't appear that the regulator is the issue, but here is the test for it .
The regulator could be one of two types, the original is a rectangular metal can with usually red tape over the seam in the metal case near the bottom, the other type is a red and black plastic module about 3/4 th's of an inch thick .
Remove the three pin connector from the regulator, and place a wire jumper between the blue wire, and the black wire terminals in the connector .
Place the meter leads on the battery .
Start the engine, and run it to about 2000 rpm's, and you should have a high voltage showing at the battery should be above 14 volts .