I would check that the plug caps are tight on the plug wire and that the plug wire is tight in the coil first. Then check all of your grounds and electrical connections for cleanliness and that they are tight. Those are the simple things to check. The only good way to test the CDI is to swap it out for a known good one. The stator will need to be checked for resistance, you can do this if you have an ohm meter. I recommend you get yourself a clymers manual, you will find it very valuable working on your own bike.