With all the hullabaloo surrounding the phase-out of internal combustion engines, the development of biofuels, and the mainstream adoption of electric motorcycles and scooters, it’s an interesting notion that diesel seems to have slipped past our radar. Diesel engines are often found in workhorse, utilitarian vehicles thanks to their longevity, efficiency, and low running costs. Wouldn’t that make them ideal for use on motorcycles?

A recent video posted by automotive YouTube sensation Donut Media goes into great detail as to why there aren’t any production diesel powered motorcycles, and boy, is it an interesting topic. The video highlights all the benefits we find in diesel engines, however these benefits are better suited to our four-wheeled counterparts, largely due to the very nature of a motorcycle. You see, a diesel motor is simpler, more efficient, and cheaper to run. This is because it makes use of fewer parts as opposed to gasoline engines. 

Royal Enfield Taurus - Main

While gasoline engines rely on a spark plug for ignition, diesel engines make use of compression ignition, which relies on the heat of the compressed air for combustion. The video explains that diesel motors last longer than their gas engines due to the fact that they operate at lower RPMs. However, the benefits end there, and it’s clear to see why diesel engines never really took off in the motorcycle world. As it would turn out, while diesel engines offer quite a lot of torque and longevity, they aren’t exactly the best option especially when it comes to razor-sharp throttle feel and rapid acceleration.

Another reason why diesel engines on motorcycles never really took off is simply because they’re too heavy. Motorcycle manufacturers are continuously innovating to make their machines lighter and more nimble. Diesel motors are simply too heavy for this because they have to be engineered to withstand significantly higher compression ratios—an essential factor in achieving the compression ignition we were talking about earlier. Additionally, given diesel engines’ compression-ignition setup, it creates more vibrations and noise, which thereby requires beefier counterbalanced and cylinder walls to deaden.

There have indeed been a few diesel-powered motorcycles in the past, and the video tackles them in detail. For instance, the Royal Enfield Taurus was a super affordable, super efficient diesel-powered machine which was basically a Bullet with a diesel swap. While it was basically a tractor with a power output of just 6.5 horsepower, it had an impressive range of 800 miles in between fill-ups—much to the delight of budget-conscious commuters. However, tightening emission standards inevitably caused its extinction.

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