BMW has built its reputation on six-cylinder power units. This configuration has particular appeal for its smoothness and refinement, but also superior power and performance plus a characteristic sound.
Looking at motorcycles, BMW Motorrad’s engineers have tried to offer the concept of a straight-six power unit but the size of the powerplant has always been a drawback.
Depending on the way the engine was fitted, six cylinders in-line inevitably made the engine either very long or very wide, creating disadvantages in terms of the running gear, weight distribution, and the centre of gravity. A further drawback was the engine weight, usually offsetting the benefits of extra power.
The BMW Concept 6 proves that a straight-six, benefiting from the most advanced construction and production technology, may offer not only a unique machine, but also one with a high standard of riding dynamics.
The new straight-six will further expand the K-Series range of motorcycles in the foreseeable future. And the first model to be introduced will be an innovative and luxurious BMW tourer.
The starting point for the introduction of the straight-six in the new Concept 6 from BMW Motorrad was the extremely compact engine. The power unit is approximately 4" slimmer than all previous straight-six production engines and only slightly wider than a large-capacity four cylinder.
The reduction in width is achieved by the slightly over-square bore-to-stroke ratio, with relatively long stroke and very small gaps between cylinders. To achieve this compact configuration with minimum width, the electrical ancillaries and their drive components are positioned behind the crankshaft and above the transmission.
High-tech lightweight construction makes the unit relatively light with two hollow-drilled camshafts and very light connecting rods. The need for a balance shaft and its drive elements was eradicated, which again means lower weight and enhanced smoothness.
In its layout, the straight-six in the Concept 6 follows the straight-four in the K 1,300 models with cylinders tilted to the front by 55˚. This ensures not only a low center of gravity, but also good weight distribution. A further advantage is the tilted engine provides extra space for the intake manifold above the engine.
The straight-six comes with dry sump lubrication for greater reliability and to keep the crankcase low and flat, allowing the engine to be fitted lower down so the mass is concentrated around the center of gravity.
Output of the new six-cylinder will be in approximately the same as on BMW’s 1.3-liter straight-four power units. Torque, on the other hand, will be at the top of the range, offering 96 lb-ft from just 2,000rpm while being able to rev to 9,000rpm.
Working on Concept 6, the designers at BMW Motorrad focused on technical function and emotional elements. Conceived as a mixture of classic and modern styling with its long front end and short rear, it uses the design language of the Café Racer.
The so-called Split Face, a design element of the latest BMWs, extends from the front fairing along the top of the carbon-fiber fuel tank and forming a contrast to the outer aluminum shell with its white layers. The division into three sections created by the Split Face is further accentuated at the front by the LED headlight and the slender LED rear light extending into the seat hump.
The Concept 6 is also underscored by the six-chamber exhaust system complete with side-pipes and the strong presence of the intake ducts again finished in platinum-look. Aerodynamic components, such as the twin-tipped engine spoiler and the air guide elements derived from the design of the new S 1000 RR Supersports bridges the gap between functional and visible technology.
The suspension of the Concept 6 is built around a light-alloy bridge frame as well as Duolever and lightweight Paralever arms guiding the wheels. 17” HP forged wheels as well as the extra-large brake system with its six-piston fixed calipers emphasize the sporting look of the new machine and its high level of technology.
The outstanding supremacy of the Concept 6 and its drivetrain is also reflected by details such as the instrument panel intentionally kept minimalist but equipped with the necessary instruments and gauges. While a digital display shows road speed, a LED display shows the rider how much torque is available instead of a conventional rev counter.