Originally Posted by Old Fox

Hi!

Came across this web-site that has excellent animations of some popular motorcycle engine configurations, namely the V-Twin and the Boxer Twin that can also be downloaded as screen-savers. The detailing is impressive and those who want to get a visual picture of what goes inside their engine can get a pretty good one here. For comparison, The Enfield Bullet engine is a push-rod actuated overhead cam engine just like the Evo and the Twin Cam below, the difference being that it is single cylinder. So go ahead and install these screen-savers....they'll give you something interesting to watch while you stare at the monitor and mull over a problem .

This one shows the Harley Davidson Evo series, an air-cooled 45 deg Twin
AnimatedPiston Animated Piston Evo Engine - Animated Motorcycle Engines

This is the Twin Cam successor to the Evo
AnimatedPiston Animated Piston Twin Cam Engine Screensaver - Animated Motorcycle Engines

And this is for the classic BMW Boxer Twin. Some variant of this engine has been in production since early 1920's.
Animated Piston BMW motorcycle engine animation by Peter Liversidge