I've gotten to ride a 2006 C50 (similar to an M50) for a weekend and everything from 5-90 mph. It buzzes like most twins at higher speeds, but nothing I found out of place (i.e., it's good to hop off every 45 minutes or so to get the feeling back in hands and feet). It had a big old national windshield and ran just fine.
Assuming it's not just that twin vibration that you mistakenly thought would be smoother, it sounds like a wheel or frame issue to me.
Assuming it's not just that twin vibration that you mistakenly thought would be smoother, it sounds like a wheel or frame issue to me.
