I had the sam exact problem and upon close inspection of the magneto area I noticed that the engine wasnt turning all the way over everytime..............the clutch wasnt completely engaging. I checked the spark plug, magneto, cdi, and everything else. What was really happening it that the clutch would only turn the motor over once in a while because of the very slight slipping. Look and confirm you see the magneto turn over and over. Good luck man
