Diesel motorcycles are relatively rare compared to their gasoline counterparts, but they do exist and offer some unique advantages and disadvantages.
Despite their unique characteristics, diesel motorcycles have not gained widespread popularity primarily due to their performance limitations and the growing focus on electric alternatives. However, for certain applications, especially in military or adventure contexts, they remain a valuable option.
Advantages of Diesel Motorcycles
Fuel Efficiency
Diesel engines generally provide better fuel efficiency than gasoline engines. This means diesel motorcycles can travel longer distances on a single tank of fuel, making them potentially more suitable for long-distance touring or military applications.
The HDT M1030M1 based off of the Kawasaki KLR650. Credit: Bike-urious
For instance, a KLR650 might get around 5L/100km compared to the HDT M1030M1, which is based on the same bike but in a diesel application, boasting mileage of 2.5L/100km.
Durability and Reliability
Diesel engines are often praised for their durability and reliability. They are built to withstand rigorous conditions and can handle higher torques at lower speeds.
Fuel Availability
Diesel fuel is readily available and often cheaper in many parts of the world, which can be a practical advantage for riders in remote areas.
Disadvantages of Diesel Motorcycles
Weight and Size
Diesel engines are heavier and bulkier than gasoline engines. This additional weight can affect the handling and performance of the motorcycle, making it less nimble and slower to accelerate.
Limited Choices
There are far fewer models of diesel motorcycles available on the market compared to gasoline motorcycles. This limits options for consumers and can make it harder to find a bike that fits specific needs.
Noise and Vibration
Diesel engines tend to be noisier and produce more vibration than gasoline engines. This can lead to a less comfortable riding experience, particularly on longer journeys.
Maintenance
Due to their distinct mechanical designs and operating principles, diesel engines generally require more frequent oil changes because they produce more soot and contaminants that end up in the oil. The oil used is typically heavier with different additive packages to handle the higher compression and combustion byproducts whereas gasoline oil is lighter and designed for higher RPM operations.
Diesel fuel systems are also more complex with high-quality fuel filtration systems to prevent impurities from clogging the fuel injectors, which operate under very high pressures. With the use of any Diesel Particulate Filter, you can expect that the DPF cleaning cost will form part of your maintenance overhead.
Gasoline engines also require fuel filtration, but the systems are generally less complex because gasoline is cleaner and the injectors operate at lower pressures than diesels.
Diesel Motorcycle Examples and Applications
- Military Use: Diesel motorcycles are used by some military forces because diesel fuel is the standard for many military vehicles, facilitating logistics. One example is the Hayes Diversified Technologies M1030M1, a military motorcycle based on the Kawasaki KLR650 but modified to run on diesel.
- Adventure Touring: Some manufacturers and custom builders have explored diesel options for adventure touring motorcycles due to their fuel efficiency and robustness, which are advantageous for long, demanding trips.
Hayes Diversified Technologies M1030M1
Credit: MXA Magazine
The Hayes Diversified Technologies M1030M1 is a military-grade motorcycle developed from the robust Kawasaki KLR650, modified to include a diesel engine capable of running on various diesel fuels, including the NATO-standard JP8. Designed for military efficiency, the M1030M1 boasts impressive fuel economy, achieving about 96 mpg on highways and 55 mpg off-road, with a range exceeding 400 miles on a single tank. Its liquid-cooled, single-cylinder engine offers a top speed of 90 mph, with enhanced durability and load-carrying capacity to meet the challenging conditions of military operations.
Royal Enfield Taurus
Credit: Reddit
The Royal Enfield Taurus was a distinctive civilian motorcycle, notable for its 325cc diesel engine, which set it apart due to its remarkable fuel efficiency. Manufactured in India, the Taurus catered to a niche market with its modest power output and slower speeds, prioritizing economical transportation over performance. The motorcycle was highly appreciated for its low operating costs, making it a preferred choice for those needing a reliable and cost-effective mode of transport.
However, despite its practical advantages, the Royal Enfield Taurus was eventually discontinued, largely due to its underwhelming performance and the increasing availability of more efficient and powerful motorcycles. While it didn’t enjoy widespread popularity, the Taurus remains a significant example of diesel-powered motorcycles, highlighting the potential for integrating diesel technology into two-wheeled vehicles for enhanced fuel economy.
Track T-800CDI
Credit: Bonhams Cars
The Track T-800CDI is a unique motorcycle from the Dutch company Track, powered by an 800cc three-cylinder turbo-diesel engine sourced from Mercedes. Designed to offer an alternative to traditional gasoline-powered bikes, this model stands out with its automatic transmission and an adventure-focused design. Its diesel engine provides considerable torque and fuel efficiency, catering to enthusiasts seeking a robust and economical option for both on-road and off-road use.
Neander Turbo Diesel
Credit: Boote Magazine
This German motorcycle is known for its unique turbocharged diesel engine. It features a parallel-twin turbo diesel engine that produces significant torque and has a distinctive, high-tech design aimed at high-performance enthusiasts.
Sommer Diesel 462
Credit: Wikipedia
The Sommer Diesel 462 is a German-manufactured motorcycle equipped with a 462cc single-cylinder diesel engine, known for its fuel efficiency and robust performance. Tailored for motorcycle enthusiasts who appreciate the uniqueness of diesel power, the Sommer Diesel 462 offers a boutique riding experience, combining the traditional feel of motorcycling with the technical advantages of diesel technology, such as lower fuel consumption and greater torque.
Diesels in the Cafe Racer World?
It’s not likely that diesel motorcycles will ever be prolific in the world of cafe racers. They may exist, but will likely come from custom projects rather than mainstream motorcycle manufacturers. A handful of enthusiasts and custom builders may opt to combine these elements to create distinctive, bespoke bikes.
This diesel bike is cobbled together from various parts, including a kitchen sink. Not quite cafe racer material. Credit: The Drive
Since cafe racers are known for their stripped-down aesthetics and emphasis on speed and handling rather than comfort, gasoline engines are the go-to. Integrating a diesel engine involves some unique challenges such as accommodating the heavier and sometimes bulkier diesel engine into the sleek and streamlined cafe racer frame.
The Star Twin ThunderStar 1200 TDI uses a Volkswagen engine. Credit: The Autopian
Custom builders who undertake these projects usually start with a diesel engine base—like those from small industrial machines or adapted from motorcycles like the Royal Enfield Taurus or other models—and modify the bike to achieve the cafe racer look. This includes custom fabrication work to fit the diesel engine neatly into the frame, reworking the suspension and brakes for adequate support and performance, and adding classic cafe racer elements like a lowered handlebar, a humped seat, and minimalist bodywork.
Diesel-powered cafe racers are more of a novelty and a labor of love, showcasing the builders’ engineering prowess and passion for unique motorcycling experiences.
