2 STROKE VS. 4 STROKE Engines
A simple explanation by Jonas Borchert
Shown in the picture is a standard 2014 Yamaha YZ250, 250cc two stroke engine. The same structured off-road motorcycle can also be ordered with a 4 stroke engine in the Yamaha YZ250F model. Although both of these engines are of the same engine displacement and have one cylinder, they have different mechanical qualities. The 2-stroke engine from the Yamaha YZ250 model produces approximately 46.4 horsepower and 30.6 foot-pounds of torque, while the 4-stroke produces 36 horsepower and 20.1 foot-pounds of torque. Now, why is this? Why is the 2-stroke engine more powerful?
In this exploration I want to prove and clarify the reason for the 2 stroke Yamaha YZ250 engine being at a mechanical advantage and the reason for it weighing less when compared to the 4 stroke engine. After working on a 4-stroke, 2 cylinder Yamaha xs400 engine in grades 9 through 11, I have developed an interest towards the mathematical aspect of an engine and the conditions needed for better engine performance.