Wis. Stat. § 347.488: Moped equipment.

No person may operate a moped unless:

(1) The moped complies with all federal emission, equipment and safety standards applicable at the time of manufacture;

(2) None of the original equipment installed on the moped by the manufacturer has been replaced with equipment of lesser performance characteristics; and

(3) The performance characteristics of the moped have not been altered so as to enable it to exceed the maximum design speed authorized for a moped under s. 340.01 (29m).