The CDI you can't really test other than checking it has input and output. The ignition coil and the stator can be ohm'ed out to check them, its in the service manual check my link in my signature below if you need the manual.
I usually take a old school test light and check the output of the stator while cranking, the follow that voltage through the system, pulse generator input and output, you should see a nice flicker on the output of the pulse generator, then i check the input of the CDI just to make sure the pulses made it through the wiring to it, and the output of the CDI at the coil input.
You will find a point at which the voltage stops. Generally, and this is just me, i swap the CDI before doing all this. Why? Because nine times out of ten when i get one of these 4 strokes to work on that has no spark its a failed CDI.
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1984 Honda ATC200ES "Big Red"
1982 ATC200E "Hondie"
1988 TRX300FW "Project Quad" Still in progress....