These are the most common scootersĀ in the US. The piston completes four movements to complete one action, to produce a power stroke. This is how they got the name, 4 stroke. Every 4 stroke scooter has oil in theĀ bottom that isĀ pumped throughout the internals of the engine. This oil must be changed regularly to maintain performance and extend the life of the scooter.Ā Available in fuel injected or carbureted scooters.