My two speeder is a rain magnet. But it has gaps in the floor and no leather to spoil. I've had to stop three times due to the rain, two of them on the same trip. A brolly is useful, as is my usual attire as the leather is horsehide, and horsehide is waterproof.
For an exposed magneto, you'd think there would be problems, but not at all. Engine kept running as I came to a stop, and re-started fine when the rain eased off.
My only complaint is in the pouring rain at Prescott, no-one held my umbrella for me as I realigned the starter after it jammed.
