You can understand this query without having any understanding of the functioning of stroke. Stroke can be regarded as the motion of the piston.  The movement of the piston is very crucial in determining the functioning of the bike. It would be best if you had a clear idea about the two and four-stroke dirt bike. Two-stroke dirt bike imparted piston motion in two different directions.  Two-stroke bikes are very unstable, and they proceed faster than the four-stroke bikes that are stable and possess higher top speed.