If you ride it on the street, you should have to have lisc., just like a motorcycle, for you and the bike.
I've maintained a fairly complete set of laws on our forums for some time, SPARKY, and while there are common parameters, some states are easier or tougher than others.
In Oregon, a bicycle with a gas engine 35cc or smaller is a "Motorized Scooter" and no documentation is required. Thats me and this bike which is normally 32cc. From 35.01-50cc is a "Moped" and license insurance and registration is required. Over 50cc is a "Motorcycle" and no way.
Some states are still at 50cc Moped no documentation, your own state AZ has a really MB friendly set of laws, and a couple allow up to 150cc!...others are NO Gas Engines on Bicycles, period.
With all that said...Not surprisingly, even the police don't always know the law, and tons of illegal bikes are on the road everywhere.
But not mine, I build and ride legal, always, because I give a carp. My Tanaka 32cc makes more power than George Wyman's 1903 200cc "California" did, I'm good with that.
This is how the smaller legal engine fits. Notice I'm using the rear "deck" to accommodate the racing engine and pipe. After the races, back to normal.