The first thing I would do is purchase a repair manual, it will have some direct resistance tests for some of your ignition components as well as a troubleshooting guide. Most likely problem is a bad coil, CDI, pickup coil or just a loose or corroded connection somewhere. A visual inspection of everything behind the stator cover and all the ignition wiring and switches would be a good place to start, but I would strongly recommend getting that manual.
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Yours truly, sincerelly, love always, Josh aka The DirtDemon.