Hawaii Revised Statutes Division 1. Government § 291C-152

(a) A person operating a motorcycle 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 unless the motorcycle 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 at the rear or side of the operator.

(b) A person shall ride upon a motorcycle, except for an autocycle, only while sitting astride the seat, facing forward, with one leg on each side of the motorcycle. A person shall ride upon an autocycle only while sitting in the seat and facing forward.

(c) No person shall operate a motorcycle while carrying any package, bundle, or other article which prevents the person from keeping both hands on the handlebars or, for an autocycle, on the steering wheel.

(d) 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 the view of the operator.