Quote:
Originally Posted by bikepilot
FWIW a lot of motorcycles are less efficient at lower rpms. ... Buell says the XB12's motor is most efficient at 4200rpm as a general matter (of it'll vary with load etc).
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That might be true, yet it's probably a very bad idea to cruise at that rpm: an 1200cc bike engine at 4200rpm needs ridiculously light throttle which gives very bad efficiency, even if the engine could theoretically do its best there. (May not be true at 90mph anymore, but most of its energy will be absorbed by the aero drag then, so it'll be inefficient again.)
Having it spin slower can mean a higher load which, eventually, almost surely leads to much better efficiency.