The bore and stroke on a cylinder determines the displacement of an engine, making bore and stroke a key element in determining engine power -- the larger the bore and stroke, the more powerful the engine. Bore and stroke are a combination of two measurements. The bore is determined by the diameter of a cylinder and the stroke is determined by the distance a piston travels up and down inside that cylinder.
Use your measuring tape to measure the inside diameter of the cylinder. This will give you the cylinder's bore.
Ensure the piston is at the bottom of the cylinder.
Measure the distance of the cylinder from the piston at the bottom to the top. This distance the piston travels gives you the cylinder stroke.