Yes, diesel motorcycles have been built and are not unheard of. While they are relatively rare compared to gasoline-powered motorcycles, several manufacturers and individuals have experimented with diesel-powered bikes.
One notable example is the Royal Enfield Taurus Diesel, which was produced in India in the 1990s. It featured a small diesel engine that offered good fuel efficiency but limited performance. However, it didn't gain widespread popularity.
There have also been custom-built diesel motorcycles by enthusiasts and engineering teams. These projects often involve modifying existing motorcycles or designing new ones from scratch. The diesel engines used in these motorcycles are typically sourced from small automotive diesel engines or industrial applications.
Diesel engines offer advantages such as better fuel efficiency and torque compared to gasoline engines, but they tend to be heavier and produce less horsepower. This makes them more suitable for certain applications like long-distance touring or off-road riding, where fuel efficiency and torque can be valuable.
Overall, while diesel motorcycles exist, they are not as common as their gasoline counterparts due to various challenges such as weight, complexity, and limited market demand. Gasoline engines still dominate the motorcycle industry due to their lighter weight, higher power-to-weight ratio, and wider availability of fuel.