I’ve been a believer for a long time that the inline-4 engine is the greatest motorcycle engine in existence. Of course, this belief is almost entirely driven by the emotion it makes me emanate. And if I have to be more specific, I would also tell you that I’m not too big a fan of the crossplane made popular by the R1. You see, it is the old-school, buttery-smooth, and loud howling which is produced as all four cylinders fire in sync, that stirs my body and soul.
Technically, all bike engines are a piece of beauty. It is fascinating to see how they work and deliver unique experiences as they move motorcycles forward. And over the years, my exposure to a variety of them has led me to develop great admiration for another engine design, BMW’s boxer twin.
And what a beautiful engine that is.
Among the parallel twins, V-twins, V4s, L-twins, inline 3s and 4s, the opposing cylinders of a boxer are as unique as they come. It is so recognizable that it is unmistakable. It is quintessential BMW.
And the boxer is a prominent factor that makes the big GS such a wonderful motorcycle to ride. It is one of the most complete motorcycles around and the flat twin is a reason. I’ll admit that I took some time to accept the way it looks. The extending cylinders on either side of a motorcycle appear vulnerable in case of a fall. But that was before I experienced one, beyond which I realized why so many riders out there just love this engine. I also realized that a company like BMW won’t be sticking with this design if it wasn’t strong and long-lasting enough.
Making its very first appearance way back in 1923 in the R32, the boxer twin has played a pivotal role in creating one of the strongest legacies in the motorcycling world. It is an extremely versatile engine and is being successfully used in BMW’s sportbikes, sport-tourers, and of course, the company’s famous adventure motorcycle.
Now, the German motorcycle manufacturer has disclosed its biggest boxer twin ever, all of 1,802cc. And BMW calls it the Big Boxer. This brand new engine will power BMW’s upcoming cruiser, which will be based on the R18 and R18/2 cruiser concept, shown in the recently concluded EICMA.
This air and oil cooled engine produces 91 HP of peak power at 4,750 RPM and 158 NM of torque at only 3,000 RPM. In its current form, it redlines at 5,750 RPM.
This large lump of metal is more than just BMW’s biggest flat twin, it is a tribute to its nearly 100 years of history. And it is a good example of old technology mixing with modern production techniques to ensure reliability without losing the old-school soul. Instead of a contemporary overhead camshaft setup, the Big Boxer gets two pushrods to operate the valves in the two cylinders. And those pushrods are aluminium and along with two camshafts that operate them, they are lighter and stronger for improved performance efficiency.
Modern touches continue with 4 valves on each cylinder and the cylinders themselves are nikasil coated. The pistons are made of cast aluminium as well. In fact, the Stroke of 100mm is shorter than the Bore of 107.1mm to ensure that the lean angle of the motorcycle is not sacrificed much. The entire gearbox is integrated into the backside of the main engine assembly. It is a 6-speed gearbox with helical gears.
Looking at the power numbers and the RPM range, it is clear that this engine is designed to run more on torque than on the horsepower. There is no ShiftCam technology from the more modern liquid-cooled 1,250cc boxer of the big GS. It appears there is no need for it as every engine has its own natural characteristics in the way they propel a motorcycle forward. The big displacement of 1,802cc and 158 NM of torque at a low 3,000 RPM will ensure instant, easy, and stress-free acceleration in all 6 gears. It is like an old-school engine but the one that belongs in the present.
I cannot wait to see the actual cruiser from BMW whenever it is finally out. Looking at the concepts, I would like to assume that the production version should be quite identical and that will be something refreshing to see in the big-cruiser segment.
All Images Courtesy: BMW Motorrad website
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