According to the Legislative Administrator at the Florida Highway Safety and Motor Vehicle Department, the proper vertical mount means turning the license plate clockwise so that the numbers and letters are read from top to bottom. If you turn your motorcycle tag counter clockwise so that it reads from bottom to top, that is illegal and you stand a good chance of getting a fine. Read FL Statute below.
316.2085 Riding on motorcycles or mopeds.—
(1) A person operating a motorcycle or moped shall ride only upon the permanent and regular seat attached thereto, and such operator shall not carry any other person, nor shall any other person ride on a motorcycle or moped, unless such motorcycle or moped is designed to carry more than one person, in which event a passenger may ride upon the permanent and regular seat if designed for two persons or upon another seat firmly attached to the motorcycle or moped at the rear or side of the operator.
(2) A person shall ride upon a motorcycle or moped only while sitting astride the seat, with both wheels on the ground at all times, facing forward, and with one leg on each side of the motorcycle or moped. However, it is not a violation of this subsection if the wheels of a motorcycle or moped lose contact with the ground briefly due to the condition of the road surface or other circumstances beyond the control of the operator.
(3) The license tag of a motorcycle or moped must be permanently affixed to the vehicle and remain clearly visible from the rear at all times. Any deliberate act to conceal or obscure the legibility of the license tag of a motorcycle is prohibited. The license tag of a motorcycle or moped may be affixed horizontally to the ground so that the numbers and letters read from left to right. Alternatively, a license tag for a motorcycle or moped for which the numbers and letters read from top to bottom may be affixed perpendicularly to the ground. Notwithstanding the authorization to affix the license tag of a motorcycle or moped perpendicularly to the ground, the owner or operator of a motorcycle or moped shall pay any required toll pursuant to s. 316.1001 by whatever means available.
(4) No person shall operate a motorcycle or moped while carrying any package, bundle, or other article which prevents the person from keeping both hands on the handlebars.
(5) No operator shall carry any person, nor shall any person ride, in a position that will interfere with the operation or control of the motorcycle or moped or the view of the operator.
(6) A person under 16 years of age may not:
(a) Operate a motorcycle that has a motor with more than 150 cubic centimeters displacement.
(b) Rent a motorcycle or a moped.
(7) A violation of this section is a noncriminal traffic infraction, punishable as a moving violation as provided in chapter 318.