Guide to Air-Cooled Motorcycles

The Enduring Appeal of Air-Cooled Engines

In an era increasingly dominated by liquid-cooled engines, the warm, visceral thrum of an air-cooled motor holds a special place in the hearts of many motorcycle enthusiasts. While liquid cooling offers superior thermal management and often higher peak power, air-cooled (or more commonly, air/oil-cooled) engines provide a simpler, more elemental riding experience. They bypass the complexities of radiators, coolant, and pumps, offering a direct connection to the mechanical heart of the machine. This article delves into the world of new motorcycles that still embrace this classic technology, exploring the manufacturers and models that continue to offer the distinct character of air-cooled powerplants.

Why Choose Air-Cooled?

The decision to opt for an air-cooled motorcycle often stems from a desire for simplicity, a connection to motorcycling heritage, and a certain aesthetic appeal. As the provided text highlights, the absence of a coolant system means no coolant to change, no leaks to worry about, and generally fewer components that can fail. However, this simplicity comes with trade-offs. Air-cooled engines typically produce less peak horsepower compared to their liquid-cooled counterparts and often require more frequent valve servicing. Despite these considerations, for many riders, the character and reduced mechanical complexity are well worth the compromise. The author’s personal preference for air/oil-cooled engines in their BMW R nineT and R 1200 S exemplifies this sentiment, valuing the lack of coolant-related worries and the inherent feel of the engine.

A Declining, But Cherished, Technology

It’s undeniable that air-cooled engines are becoming a rarer sight in the new motorcycle market. As emissions regulations tighten and manufacturers push for higher performance, liquid cooling has become the dominant choice. The author notes this trend, drawing parallels to the automotive industry where air-cooled engines are now almost exclusively museum pieces. This makes the current availability of new air-cooled motorcycles all the more significant, offering a chance to own a piece of motorcycling history that will likely become a collectible in the future. The term “air-cooled” is often used as shorthand, but it’s important to note that most modern examples are technically “air/oil-cooled,” incorporating an oil radiator to aid in temperature management.

BMW: Heritage in Air-Cooled Form

BMW continues to champion the air-cooled engine in its “Heritage” line-up, much to the delight of enthusiasts. The BMW R nineT, a motorcycle that helped spark renewed interest in this engine type, remains a prime example. Even with modern rider aids like ride-by-wire and cornering ABS, its 1170cc boxer engine is still air/oil-cooled. This engine, a descendant of BMW’s “Camhead” or “Twin cam” units, produces a respectable 81 kW (110 hp) and revs to around 10,000 rpm. The introduction of the BMW R 18 further solidified BMW’s commitment to air-cooled power. Featuring a massive 1802cc opposed twin, the R 18 prioritizes torque, delivering 158 Nm (117 ft-lb) from low revs. This all-new engine, while making less peak power than some competitors, showcases the unique character of a large-displacement air-cooled unit. BMW also offers the updated R 12 nineT and the R 12, both retaining the core twin-cam boxer engine, albeit with chassis and suspension refinements.

Ducati: Timeless Desmodromic Charm

Ducati, while known for its high-performance liquid-cooled superbikes, keeps its air-cooled heritage alive in its Scrambler line. The Ducati Scrambler 800 and the larger Ducati Scrambler 1100 utilize engines derived from older, beloved models like the Monster series. The Scrambler 800 is powered by an 803cc air-cooled L-twin featuring Ducati’s signature desmodromic valve actuation, producing around 75 hp. The Scrambler 1100 ups the displacement to 1079cc, delivering 85 hp and more torque, with both models sharing 12,000 km (7,500 miles) service intervals. These bikes offer a taste of Ducati’s classic character, blending modern usability with timeless engine technology.

Harley-Davidson: The King of Air-Cooled V-Twins

Harley-Davidson’s identity has long been intertwined with its large-displacement, air-cooled V-twin engines. While the introduction of liquid-cooled models like the V-Rod, LiveWire, and Pan America might suggest a shift, the vast majority of Harley-Davidson’s current range remains air-cooled. The Milwaukee-Eight engine, introduced in 2016, powers most of their modern cruisers and touring bikes. Available in 107, 114, and 117 cubic inch displacements, these 45-degree V-twins are air/oil-cooled and feature eight valves per cylinder. The iconic Evolution engine, found in the Sportster line since 1986, is also a notable air-cooled powerplant, known for its distinctive 2-valve, twin-cam design. While Harley-Davidson has experimented with "precision liquid cooling" in cylinder heads for some premium models, their core offering remains the inimitable sound and feel of an air-cooled V-twin.

Honda: A Nod to the Past

Honda’s modern motorcycle line-up is predominantly liquid-cooled, having phased out most of its air-cooled road bikes. The beloved CB1100, a retro-styled four-cylinder machine, has been discontinued. However, Honda still offers the rugged XR650L in some markets. This dual-sport motorcycle features a 644cc SOHC air-cooled thumper engine and even retains a carburettor. For a more road-focused experience, the Honda H’ness CB350 and its sibling, the CB350RS, offer a modern take on classic styling with a 348cc air-cooled single-cylinder engine. These bikes deliver a relaxed riding experience, with the CB350 producing around 21 hp.

Kawasaki: Retro Charm with the W800

The Kawasaki W800 stands out as Kawasaki’s sole remaining air-cooled model, a tribute to the brand’s earlier W650. Available in standard and Café variants, the W800 is powered by a 773cc SOHC parallel-twin engine that is, remarkably, purely air-cooled, lacking even an oil radiator. With a low compression ratio of 8.4:1, it produces a modest 48 hp, making it an accessible option, particularly for newer riders or those prioritizing classic aesthetics and a relaxed pace. The W800 also shares 12,000 km (7,500 mi) service intervals with some Ducati models.

Indian: Thunderstroke Power

Indian Motorcycles, another brand with a rich heritage in air-cooled V-twins, continues to offer several models with its Thunderstroke engine. While the Indian Scout, FTR, and Challenger models feature liquid-cooled engines, the Indian Chief line, including the Chief Bobber, Super Chief, Chieftain, Springfield, Roadmaster, and Vintage, are all powered by the air/oil-cooled Thunderstroke V-twin. Available in 111 and 116 cubic inch (1811cc and 1890cc) displacements, these engines are 49-degree V-twins with 2-valve heads and hydraulic lifters. The Thunderstroke 116 boasts a higher compression ratio (11:1) compared to the 111 (9.5:1), offering increased performance.

Moto Guzzi: Transverse Twins

Moto Guzzi, an Italian manufacturer renowned for its characterful and aesthetically pleasing motorcycles, largely adheres to air-cooled engines, often paired with shaft drive. Their transversely mounted V-twin engines, with cylinders flanking the rider, benefit from excellent air flow. Models like the Moto Guzzi V85 TT adventure tourer and the Moto Guzzi V7 Stone are prime examples, both utilizing an 853cc air-cooled 90-degree V-twin. While Moto Guzzi introduced liquid-cooled engines in late 2021 with the Mandello V100 and the reborn Stelvio, the vast majority of their current offerings remain true to their air-cooled roots.

Royal Enfield: Accessible Classics

Royal Enfield, a brand synonymous with vintage motorcycling, continues to produce a range of air-cooled models. The Royal Enfield 650 Twins, the Interceptor 650 and Continental GT 650, are powered by a modern yet air/oil-cooled 648cc parallel-twin engine. This engine, with its 270-degree crankshaft, offers a pleasing character and is known for its reliability and ease of maintenance, requiring no premium fuel due to its modest 9.5:1 compression ratio. Other Royal Enfield models, such as the Himalayan adventure bike and the Meteor 350, also feature air-cooled engines, making them accessible and enjoyable options for a wide range of riders.

Suzuki: Enduring Simplicity

Suzuki offers a couple of stalwart air-cooled models that have stood the test of time. The Suzuki Boulevard S40 (also known as the LS650 Savage) is a lightweight cruiser powered by a 652cc SOHC air-cooled single-cylinder engine. While discontinued in some markets, it remains a popular choice for its manageable power and approachable nature. More famously, the Suzuki DR650SE continues to be produced in its virtually unchanged, air-cooled, carburettor-fed form. This dual-sport icon features a 644cc SOHC motor and is a testament to the durability and simplicity that air-cooled designs can offer.

Yamaha: The Bolt and Beyond

The Yamaha Bolt, along with its variants and the SCR950 Scrambler, represents Yamaha’s current offering of new air-cooled motorcycles. The Bolt is powered by a 60-degree air-cooled V-twin engine, similar to that found in the V-Star 950. Designed as a Japanese alternative to bikes like the Harley-Davidson Iron 883, the Bolt prioritizes style and relaxed cruising over outright performance. Until 2017, Yamaha also produced the kickstart-only SR400, a minimalist single-cylinder machine that perfectly embodied retro simplicity.

Smaller Capacity Air-Cooled Machines

Beyond the larger displacement models, numerous smaller-capacity motorcycles also utilize air-cooled engines. These are often found in dual-sport, pit bike, and commuter segments, where it’s easier to meet emissions and noise regulations. Notable examples include the Honda Grom, Monkey, and Super Cub, all featuring 124cc air-cooled singles. Similarly, the Kawasaki Z125 Pro offers a 125cc air-cooled single. Many Chinese and Indian manufacturers also produce a wide array of sub-200cc air-cooled motorcycles.

The Future of Air-Cooled

While the trend towards liquid cooling is undeniable, the continued availability of new air-cooled motorcycles from manufacturers like BMW, Harley-Davidson, Indian, Royal Enfield, and others is a cause for celebration among enthusiasts. These machines offer a tangible connection to motorcycling’s past, providing a unique character and a simpler mechanical experience that many riders cherish. As these engines become increasingly rare, their appeal is likely to grow, making them desirable not just for their ride, but as rolling pieces of history.

Frequently Asked Questions

What are the main advantages of an air-cooled engine?

Simplicity, fewer parts, no coolant to change or leak, and often a more direct mechanical feel.

What are the disadvantages of an air-cooled engine?

Generally lower peak power output compared to liquid-cooled engines, and potentially more frequent valve servicing.

Are all “air-cooled” bikes truly just air-cooled?

Most modern examples are technically “air/oil-cooled,” meaning they incorporate an oil radiator to help manage engine temperatures.

Which manufacturers currently offer new air-cooled motorcycles?

As of the information provided, BMW, Ducati, Harley-Davidson, Honda, Kawasaki, Indian, Moto Guzzi, Royal Enfield, and Suzuki offer models with air-cooled engines.

Will air-cooled engines disappear completely?

It is likely that new air-cooled engines will become increasingly rare due to stricter emissions and performance demands, similar to trends seen in the automotive industry.

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