I have an '80 Motobecane Moby 50 with a Variator
clutch. I seem to have developed an engine vibration.
The vibration is not noticeable when riding the bike.
It is the most noticeable at about 1/4 throttle but is
faintly there at all times while on the kickstand.
You can visually see the engine vibrating. I checked
the rubber mount bushings but they seem fine. The
engine runs fine; accelerates, pulls good, idles fine.
I am afraid there is something internally wrong but
as of now I do not know what to think.