Honestly, about the only difference I can see between the left and right cylinders, is cooling. The left cylinder is slightly less exposed to airflow, since the engine is offset to the right in the frame(which thrusts the right side out into the airflow more, while the left is partially blocked by the frame and front wheel), so maybe there are slight differences in air density (with the carb being potentially a few degrees cooler), don't know. That's all I've got now...
