2004 Honda Interceptor 800

The 781cc V-Four has a pair of Siamesed cylinders set 90 degrees apart, its 16 valves are actuated by a pedestrian cam chain. It's fueled by 12-hole fuel injectors and is wrapped by a pair of slim-line radiators that peek through the fairing's side vents. Finally, the engine boasts iridium-tipped spark plugs, an air-injection system and a three-way catalyst—technology that helped earn the motor a seven-year federal smog certificate—good until the 2008 model year.