The water-cooled Boxer’s cylinder heads have been rotated forward 90 degrees. The intakes
BMW’s trademark Boxer engine is more than iconic. Introduced as an industrial engine in 1921 and first fitted in a motorcycle two years later, those jutting, horizontally opposed cylinder heads have been a signature of BMW motorcycles for nearly 90 years. And no bike has been more closely associated with the Boxer engine in recent years than the equally iconic R1200GS, which invented modern adventure touring when it was released as the R80G/S in 1980. The giant GS has since become BMW Motorrad’s best-selling model. More than 30,000 examples are sold worldwide each year, accounting for one-third of total BMW motorcycle sales. Why on earth, then, would the Munich-based manufacturer risk massive customer loyalty and consumer acceptance by making a major change like adding water-cooling to this flagship model?
Because it has to. The current 1170cc Boxer engine is already straining to keep up with more powerful competition, even after the addition of DOHC heads from the HP2 Sport last year. Liquid-cooled engines make more reliable horsepower.
Emissions compliance is also an issue. Motorcycles are mandated to meet tighter Euro 4 standards in 2012, with Euro 5 compliance on the horizon three years later. Some suggest the current air/oil-cooled Boxer will have difficulty meeting these demands. Liquid-cooled engines warm up faster and run at cooler, more consistent temperatures, improving combustion efficiency and reducing overall emissions. Liquid-cooled engines also muffle mechanical clatter better, so NVH (noise-vibration-harshness) emissions are greatly reduced as well.
For all those reasons, expect to see a new, liquid-cooled Boxer replace the venerable Oilhead later this year. Well-disguised prototypes (shown here) have already been spotted undergoing testing at BMW’s Munich Development Center. Compact radiators, cooled by small electric extraction fans, are located under large air shrouds on either side of the steering head. Close inspection also reveals that the cylinder heads have been rotated forward 90 degrees. The throttle bodies are now located above the cylinders, in true downdraft orientation, and exhaust now exits from below the cylinders—rather than the front—presumably to improve combustion efficiency.
Numerous chassis upgrades are evident as well. Front brake calipers are now radial-mounted and the rear tire appears wider—perhaps 170mm to replace the present 150mm fitment—suggesting an upgrade in both load capacity and handling. The rear of the bike has been flip-flopped: The exhaust now exits on the right side and the shaft drive is located on the left. This has some GS-junkies speculating about a new and hopefully more reliable transmission and final drive, perhaps now with a wet clutch like the K-bikes, to improve a notorious weakness with the current GS platform.
The R1200GS is traditionally a techno-logical showpiece, so debuting the liquid-cooled Boxer engine on this model makes sense. The original Airhead GS might have been celebrated for stone-ax simplicity that allowed anyone with a sledgehammer and stick welder to field-service the bike at the most remote Siberian outpost, but it’s been a sled-dog’s age since then. Oil cooling was added in 1995, and in this era of EFI, Integral ABS, Electronic Suspension Adjustment, ASC traction control and more, liquid cooling might be the least complex technology added to the GS in at least two decades.
Technophobes protested when Porsche abandoned air-cooling on its iconic 911 model in ’98, but the water-cooled Type 996 that followed launched a new era of performance without sacrificing character or capability. The situation will likely be the same for BMW, introducing a new level of performance and practicality, making the Boxer engine relevant and attractive to the next five generations of motorcycle enthusiasts.