I'd have bought Hondas if I could register them as mopeds here, but there are 3 classes of registration here in Massachusetts.
Moped: 30mph max, no clutch, automatic shift. No insurance, ride with a car or motorcycle drivers licence or Learner's Permit.
$40 every 2 years to register, Bill of sale required. No safety inspection as far as I can tell. (strange for this state to miss the opportunity to collect another fee) Modifications are of course illegal so don't get caught if you make any. I've read on different RMV pages that mopeds may only have top speeds of 25mph and scooters 20mph, but they contradict themselves many times, best not to say anything about top speed, or claim 20mph if asked. My scooters are on their list so I should have an easy time.
Limited use Motorcycle: 40mph max, Insurance required, ride with a car or motorcycle drivers licence or Learner's Permit. No highway use.
Motorcycle: well you know...
They https://www.mass.gov/orgs/massachusetts-registry-of-motor-vehicles have a
list that gets updated every few years to determine what is legally what, I'm not sure what to do if your moped or scooter isn't listed. I bought models that are both listed as mopeds. A 2013 Kymco People 50 with 5300KM and a 2003 Piaggio LT50 with 807 miles (bought separately) both 2 stroke, both with 16" tubeless wheels. I've got $1050 into the pair plus tires, drive belt, front brake pads, fork seals and tune up parts for the Kymco so far.