Our displacement calculator helps determine your engine's size by its bore and stroke. This is a very useful tool for building high-performance racing engines. It's important in some kart and racing classes that restrict the cubic inches or cubic centimeters of the engine. The Bore measurement is the diameter of the engine's cylinder. The Stroke can be measured in two ways: The total distance the piston travels between the top dead center (TDC) and bottom dead center (BDC) or by measuring the distance between the crankpin center and the crank bearing center and multiplying it by two. These measurements are typically listed in our product description but for the most accurate results, the bore and stroke need to be measured in the final engine assembly.