The following four criteria must be met in order to be considered a moped; otherwise it is a motor-driven cycle and requires a Class L license. If all four criteria are met, the operator of a moped may drive it with any valid driver’s license of any classification.
A motorized pedalcycle is a motor-driven cycle with speed attainable in one mile of 30 mph or less.
Equipped with a motor that produces 2-brake horsepower or less.
If an internal combustion engine is used, displacement shall not exceed 50cc.
Power drive system shall not require the operator to shift gears.
Licensing, Registration, and Insurance
You must have a valid drivers license
You must have a title for the moped,
You must register the moped with the state
You must have plates on the moped
You must have insurance for the moped.
If you do not have a title, you will need a bill of sale from a state that does not require one. Close states that fit this criteria are Indiana and Missouri.
The bill of sale needs to state Year, Make, Model and if you can put that the moped is 49cc or under, that helps.
$25 sales tax
If problems arise, find the nearest vehicle titling/registration buisiness, they will give you no problems, although there will be a small fee (usually around $20).
Another way to get a title for any untitled vehicle, including a moped:
Have the vehicle appraised by a third party. For mopeds, this will probably be a motorcycle dealer.
Put up a deposit in the amount of one and a half times the appraisal value. This deposit is refundable after three years, and exists in case someone else makes a valid claim on the vehicle.
Pay the regular fees for title and plates. $65 for title, $38 for plates for one year.
Rules and Regulations
Must obey all signs, signals and traffic laws and most bicycle laws.
Drivers may carry a passenger only when the moped is made for two people. Equipment must include a passenger seat and a passenger footrest.
If a moped is driven at night, it must have a headlight visible from at least 500 feet and have a red reflector on the rear visible from at least 100 to 600 feet
Helmets are not required in Illinois, but eye protection is.
Taken from moped2.org and Cyberdriveillinois.