I am thinking this also or something in the electronic side of the primary ignition. the Pertronix magneto or what ever type ignition they use. Is there an air gap ajustment? I would think the module if it was electronic. i would do the distributor cap off turn the crank and see how much slop in the chain before tearing it apart. start easy then tear the engine apart but dont go straight for engine internals. It could be electrical. How are the grounds for the ignition? any High resistance connections?
