I believe your motorized bicycle is considered a moped in WI.
Anyone who drives a motorcycle must have a Class M motorcycle license or motorcycle instruction permit.
Moped drivers do not need a Class M license. They can operate a moped with a Class D regular or probationary license. However, it is not legal to operate a moped with only a valid instruction permit.
A moped is:
Any of the following vehicles (excluding a tractor) capable of speeds not more than 30 mph, with 150 lb. Rider on a dry, level, hard surface with no wind, a power source as an integral part of the vehicle, and a seat for the operator:
- A bicycle-type vehicle with fully operative pedals and an engine certified by the manufacturer at not more than 130cc.
- A Type 1 motorcycle with an automatic transmission and engine certified at not more than 50cc.
A person must hold a Wisconsin motorcycle instruction permit or surrender a valid motorcycle license from another state before they may obtain a Class M license.
Ref:--->
https://wisconsindot.gov/Pages/dmv/motorcycles/mc-how-aply/mc-md-lic.aspx