625 ILCS 5/1-148.2: Moped.

A moped is a motor-driven cycle, with or without optional power derived from manually operated pedals, whose speed attainable in one mile is at least 20 mph but not greater than 30 mph, and is equipped with a motor that produces 2 brake horsepower or less. If an internal combustion engine is used, the displacement shall not exceed 50 cubic centimeter displacement and the power drive system shall not require the operator to shift gears.