I had this problem for over a year a couple years back. I ripped everything off the frame and cleaned it up. I rattle canned the frame with chrome/silver paint. When I put it all back together I had no spark. Went through the entire harness and every wire had continuity. Sanded down the grounding spots. Checked on/off switch which was good. Bypassed key switch just for good measure. Still no spark. Bought a new coil cause it tested bad. No spark. Bought new stator even tho it was within specs. No spark. Finally bought the most expensive part (cdi). No spark. I let it sit in my grandparents garage for a very long time. One day I decide to use part of an amp wire from my old system to ground the frame to the engine and BAM spark.