Illegal in New York City
http://www.nydailynews.com/new-york/exclusive-police-crackdo...
So, $1500 -- and it will be confiscated. Another set of fines could be applied $500 + no insurance, no registration, possibly no motorcycle license. These things cannot be registered -- so no way to make them legal under current New York legislation.
Ignorantia juris non excusat