This 1”-bore, 1-3/4”-stroke single-cylinder engine is often called a “flame licker” engine. An alcohol flame is placed outside a valve opening on the cylinder. When the valve opens and the piston moves back, a flame is drawn into the cylinder. The valve then quickly closes and the gas burns the oxygen before cooling and creating a vacuum. Atmospheric pressure then pushes the piston back, and the flywheel carries the cycle through to start again. Though it doesn’t produce much power, it can run at up to 1,100 rpm. Proximity of the flame to the valve opening is what determines the engine speed.