The two-cylinder layout is exceptionally common in the world of motorcycles. This bike has the most powerful two-cylinder in ...

As the engine heats up, the spring inside the thermostat expands and pulls the valve open. Electric chokes use the vehicle's 12-volt power to control the thermostat.

Near redline, the valves may bounce off their lobes, and valves and pistons can collide. Stiffer valve springs can alleviate this "valve float," but they bring friction and noise.

In the early days of motorcycle racing, the metallurgy simply wasn't available to build the strong valve springs necessary to avoid valve float at the engine speeds Ducati wanted to build.

One downfall, however, is their ability to rev. Pushrod engines tend to have rather low redlines. You won't find a GM small-block V-8 revving to 9,000 rpm, but there's a reason for it all.

Posted in Engine Hacks Tagged 4-stroke, DIY engine, Engine hacks, gasoline, machining, Otto cycle, rotary valve ← The Little Replacement PSU That Could: Kill A Microsoft Surface And Monitor ...