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I recall reading that the super rich mixture in the crankcase was above the Upper Explosive Limit. There wasn't enough oxygen for it to ignite until it was diluted with more air in the cylinders, as described by 'farqueue'.
Also I think many rotaries had a conventional throttle. Main problem was the slow acceleration of the rotating mass. If the throttle was slammed open from low revs, the air velocity through the wide open throttle would be too low, to pick up the fuel, and the engine would die. To prevent this, the throttle had to be opened in small steps, allowing the revs to build beween the steps.
No wonder the rotary died out when improvements in metallurgy and design solved the cooling problems of early static radials.
Spec.