Motorized bikes
I emailed SOS about this issue last year and received a response that there is no process to register a motorized bicycle, a motorized bicycle is not a moped and it is legal to operate it on Michigan roads.
So on the roads you have to operate like a bike/vehicle and stop for signs/lights/pedestrians etc, have a headlight at night, rear red reflector or red light and minimally be able to hand signal. I would also highly recommend a horn. I put a pair of Cadillac horns on mine. Oh yeah!
Btw in Michigan mopeds (which a motorized bicycle is not) go up to 100cc.
I have an engine cover on my 80cc that shows "48cc" just in case. Lol
It ran great until my coaster brakes snapped, my rear axle loosened up and the rear tire started wobbling dangerously. Don't use coaster brakes!
But don't take my word for it. I'm just some random A-hole on the internet that is probably talking out of his butt like people tend to do nowadays. I suggest that if you have any questions about the legality that you should email the SOS like I did, print out the email response saying it is ok, and carry it with you while riding. Like I did. After all you are the one chancing a ticket and/or jail, not me.
Ok back to the drawing board. Time to add hand brakes.