I always suspected one could troubleshoot the ignition system without a voltmeter but never had tried to till the other day. My bike was intermittently cutting out like an on/off switch was being thrown so i knew it wasn't a mechanical problem. Then it completely died and wouldn't restart. I pulled the plug and there was no spark when cranking the engine with the plug pressed against the head. Then I disconnected the CDI from the high voltage coil and held the CDI connector in my fingers while contacting the grounding screw with my little finger. Then when cranking I felt a little shock. I couldn't feel it while the two were connected together. So then I knew that the stator coil and the CDI were good but out of curiosity I disconnected the stator coil from the CDI and held the stator coil wires while cranking and got a mild shock which indicated the coil was producing voltage for the CDI.
I then went home to find a coil that would work, brought it back and installed it, and the bike was running again.
:-)
ps- even with a voltmeter it is hard to check the output of the CDI since it produces a spike of voltage that is very quick and probably won't show up on the meter.