As for the lower BGM stators, maybe they were just being cautious, allowing for additional clearance so they fitted all combinations of flywheels / flywheel tapers out there. The cynics might say that they are planning world Lambretta ignition domination ensuring only their stator works with their flywheel, but I doubt it.
Heat, vibration, clumsy mechanics etc all play havoc with stator plates..... Luckily things Lambretta engines never experience
