From the V-8-powered Boss Hoss to the Sears Allstate “Twingle” (split-single), motorcycle engines have enjoyed a quizzical variety of configurations. In a future Top 10 we’ll countdown the most bizarre motorcycle engines, but for this list let us examine the engines that have come to dominate motorcycle power production.
Boss Hoss doesn’t own the patent for V-8-powered motorcycles. Morbidelli produced an amazingly bland sport-touring model in the mid-’90s, but probably the most awesome V-8 motorcycle was the Moto Guzzi Grand Prix racer of the 1950s (pictured above). There’s also a history of Franken-engines machined to life in garage laboratories of mad engineers anywhere motorcycle enthusiasts are found.
9. Inline Six
We’re super appreciative BMW brought back the inline six-cylinder in its K1600 models. The engine configuration had a popularity contest in the late ’70s and early ’80s with Benelli, Honda, and Kawasaki (pictured) all manufacturing some version. Let us not overlook, however, the most badass Six to ever exist, the 250cc RC166.
8. Opposed Four/Six
Honda pretty much owns this engine configuration. The flat-Four/flat-Six has powered every Gold Wing model since 1975, as well as a few others: F6B, Rune, Valkyrie. Besides Honda, a few OEMs have produced opposed-Fours including Wooler and Zundapp. Brough Superior produced a crazy-cool opposed-Four (pictured) where the cylinders were stacked vertical, instead of horizontal.
7. Opposed Twin
Like Honda’s ownership of the opposed-Four/Six, BMW is the OEM most closely associated with the flat-Twin. It became known as a Boxer for the way its pistons hammer back and forth. Matter of fact, BMW’s first motorcycle, the 1923 R32, was powered by a flat-Twin. In a time before ubiquitous liquid-cooling, the flat-Twin was an obviously efficient way to air-cool an engine, putting both cylinders into clear airflow. Ural and Dnepr utilize the same cylinders-in-the-wind design as BMW, but Douglas (pictured) mounted the cylinders of its opposed-Twin between the wheels.
Could be their compact size, the odd number of cylinders, the combination of four-cylinder revviness and Twin-like torque, the wailing drone they make when on song, or all of the above that endears inline-Triples to many motorcyclists. We were happy to see a resurgence of Triple-powered motorcycles beginning with Triumph in the 1990s, then MV Agusta and now Yamaha. Most who have owned a three-cylinder forever have a soft spot for the engine configuration.
The compact design of the V-4 has found its way into numerous race bikes – it was the go-to configuration for 500cc two-stroke Grand Prix machines for two decades. The V-4 also makes for a unique streetbike engine: Interceptor, Magna, Motus, ST1100, VMAX, etc. The most famous/unique V-4 is Honda’s NR750 – the only oval-piston engine now, and probably forever.
4. Parallel Twin
When the Brits ruled the motorcycle universe, the parallel-Twin was their engine configuration of choice, powering everything from Triumph Bonnevilles (pictured), to BSA Rockets and Norton Commandos. Triumph’s 1937 Speed Twin can be credited with starting the trend. Triumph continues using the parallel-Twin design in many of its modern retro models, as do other OEMs such as Honda (NC700, Africa Twin), BMW (F800 lineup), Kawasaki (EX500, Ninja 650) Yamaha (Super Ténéré), just to name a few.
The single-cylinder engine has probably powered more motorcycles – street and dirt – than any other engine configuration. Early on, the Single was the most uncomplicated engine to produce and maintain, and it still is. While use of Singles has waned in popularity among street bikes, modern dirt bikes all utilize single-cylinder engines. Some noted modern street bike exceptions include KTM’s 390 and 690 Dukes, Suzuki’s Boulevard S40, and Yamaha’s SR400. Most scooters also utilize single-cylinder engines.
The Big Four’s UJMs made inline-Fours famously popular, beginning with Honda’s 1969 CB750 Four, but the four-cylinder engine existed long before the Japanese made it their own. MV Agusta successfully raced four-cylinder Grand Prix bikes beginning in the 1950s, and Gilera’s four-cylinder Grand Prix success was realized prior to MV’s. Outside of racing, four-cylinder motorcycles have been produced by various OEMs including Indian and Pierce (pictured).
Without the V-Twin, American motorcycle production would almost cease to exist; all current models from Harley-Davidson, Indian (pictured) and Victory are only available with a V-Twin powerplant. Even though Ducati has recently been describing its engines as L-Twins in an attempt to distinguish them, they are simply 90-degree V-Twins rotated forward in their frames. Moto Guzzis also use 90-degree V-Twins, which have perfect primary balance as opposed to narrower-angle V-Twins. All the Japanese brands have V-Twins in their lineup, as does KTM, Aprilia and most defunct motorcycle manufacturers. The V-Twin configuration is arguably the best combination of aesthetics, economy, sound, and performance.