This company has the best website by far.
BMS Motorsports Inc.

http://www.bmsmotor.com/

I am fine with a 50cc if its a two stroke and offers at least 5hp.

There is no special class for them in Ohio they are considered motorcycles. The only other classification is that of a Moped and those have peddles and cannot go over 20mph and cannot have breaking hp over 1.

The 150cc range from 9hp to 6hp....