While The regulations and laws regarding vehicle modifications, including steam-powered motorcycles, can vary from country to country. However, it is important to note that building a steam-powered motorcycle may present certain challenges due to safety, emissions, and compliance requirements.
In many countries, road-legal vehicles must meet specific standards and regulations regarding emissions, noise levels, safety features, and vehicle types. These regulations are often designed for internal combustion engine-powered vehicles and may not have provisions for steam-powered vehicles. As a result, it might be difficult to legally register and operate a steam-powered motorcycle on public roads.
That being said, it is advisable to consult the specific regulations and requirements of the country or region where you intend to build and operate a steam-powered motorcycle. Contacting the local transportation authority or relevant regulatory agencies can provide you with the most accurate and up-to-date information regarding the legality and requirements for such vehicles.
Furthermore, it's worth noting that even if it is not possible to legally operate a steam-powered motorcycle on public roads, there may be opportunities to showcase or ride the vehicle on private property, at specialized events, or in countries or regions with more lenient regulations for unique or experimental vehicles.