If the "pocket bike" has an engine displacement of 50cc's or less, produces 2.0 brake horsepower or less, is capable of a top speed of no more than 30 mph, and the operator is not required/allowed to shift gears, then it may be legally classified as a moped. The document titled "Moped Requirements" lists the operational and equipment requirements for such motor vehicles. Most "pocket bikes" will not meet those requirements and therefore will not be street legal. If the "pocket bike" has an engine displacement greater than 50cc's then it is classified as a motorcycle and must meet the requirements applicable to that type of vehicle. Again, most "pocket bikes" will not meet these requirements.
A goped, while not specifically defined in the Michigan Vehicle Code, does fall under the definition of a moped (MCL.257.32b). Mopeds are required to have certain equipment such as; a headlight, brake light, seat, horn, muffler, and brakes on each wheel, in order to be legally operated on the roadway. In addition, the operator of a moped must be at least 15 years of age, have a moped license or an operator/chauffeur license, and the vehicle must be registered with the Department of State and display a valid registration plate. Finally, a person operating a moped must wear an approved safety helmet if they are under 19 years of age. Because gopeds are not equipped with the required equipment they cannot be legally driven on the roadway. Also, by definition they are a motor vehicle and therefore cannot be driven on a sidewalk constructed for use by pedestrians.
Moped General Information
Riding a Moped Safely Pamphlet
Assuming your golf cart is electric powered, then it may be possible to register it as a low speed vehicle. The document titled "Low Speed Vehicle" lists the operational and equipment requirements that must be met. If the cart is other than electrically powered it can only be legally operated on a highway, (including the right-of-way) in the State of Michigan, under very strict circumstances. In those situations it would be defined as an ORV found in MCL 324.81101 and circumstances allowing operation on a highway while severely limited can be found in the Natural Resources and Environmental Protection Act, MCL 324.81122. Local municipalities can authorize situations where an ORV can be operated on a highway within their jurisdiction. MCL 324.81131 defines those situations.