Old Sportsters shifted on the right. Along with Triumph's, BSA's, Ducati's and probably other
European bikes. Big Harley's shifted on the left. Then the Japanese FLOODED the world with
affordable fun motorcycles---which all shifted left foot. Eventually the rest of the world
switched to left foot, expecially if they wanted to sell motorcycles!
Had a Ducati for a while right out of high school. 250cc single, set up for dirt (probably a good thing
it wasn't a road bike). It shifted right foot, and it was DOWN to shift UP. I
would forget which bike I was riding, come screaming down on a corner , stomp down with my right foot to
hit the brake and shift it up a gear. After going on my a$$ about a hundred times I sold it.