Someone in here was riding a BMW 650cc bike named Teresa, he was getting impressive numbers. As far as I understand a single big cylinder is the most efficient. A automotive article from Car & Driver emphasized that 500cc cylinders, with long stroke, where becoming standard size for engines of the big car manufacturers. Weather it be a 4 cylinder or eight, 500cc per cylinder was determined to be the most efficient.
Why 0.5-Liter Cylinders Will Soon Dominate Automotive-Engine Design
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