Small Gas Engines - Two Cycle and Four Cycle Engines - Chapter 5

the distance moved by the piston.

an explosion occurs every other revolution of the crankshaft. A cycle is considered as a half revolution of the crankshaft. The cycles are intake, compression, power, and exhaust.

piston moves downward, increasing cylinder volume, and creating a partial vacuum that draws air-fuel mixture through the intake valve port into the cylinder.

the reduction in volume or the squeezing of a gas.

air-fuel mixture is ignited and the force of the explosion forces the piston downward in the cylinder.

the spent fuel after combustion takes place in an internal combustion engine.

all exhaust gases are removed from the combustion chamber

the degree at which the valves open or close before or after the piston is at TDC or BDC. Timing marks on the crankshaft and camshaft gears are aligned.

TDC. When the piston is at the top of its movement in the cylinder.

BDC. When the piston is at the bottom of its movement in the cylinder.

an interval expressed in degrees where both valves of an engine cylinder are open at the same time.

an engine design permitting one power stroke for each revolution of the crankshaft.

engine that has a special contour on the piston head, which acts as a baffle to deflect the air-fuel charge upward in the cylinder.

engine does not have to deflect the incoming gases, so it has a relatively flat or slightly domed piston.

a valve construction in which ported holes move in and out of register with each other to allow fluids or gases to enter and exit.