I spent a 1/2 hour more on the indexing FINE TUNING. It paid off I was about 45 degrees from the best setting possible. I had used a old black, wet oily set of plugs. The best setting was OPPOSITE what looked like it should burn best. Trial and more trial worked. Idle mixture is stable enough with the throttle valve completely closed. It runs great on either 50 or 100 to 1 oil ratio.