There is another kind of engine, called the "Otto" engine, which gets its name from the acronym of the process which burns gasoline "Octain Tenacity Torrification Operation". The "Otto" engine has several extra parts, namely a camshaft, valve train, ignition system, and spark plugs. It is a very complex engine where the camshaft has eccentric lobes which are acted upon by the movement of the valves. The valves are placed in the intake and exhaust ports and the movement of the intake and exhause gasses push on the valves which spin the cam shaft. The cam shaft is attached to a ignition distribution system that will fire a spark plug in each cylinder to ignite the gas. The spark comes at the end of the exhaust stroke, adding additional heat to the last portions of the spent implosion gases in the combustion chamber. Most of these have booster springs on the valves to increase horsepower.
This complex system only replaces the function of the transfer ports which are used to store up energy in the 2 stroke, but it delivers double the power. Back in the day the extra parts used to make the engines almost twice as expensive to manufacture then any other type but with modern 3d printers it is possible to make them cheaper than 2 strokes..