After going through the wiring for the second time and tearing the carbs down (clean as a whistle) it was about all that was left to try. Not sure how to diagnose this particular problem other than to eliminate each potential problem until there is only one left. Maybe with an old oscilloscope you could see an oddity in the firing but I haven't seen one in a garage in several years. Maybe I just haven't looked in the right places since I know they are still on the market.
