Here's a translation of a recent Motorrad article on the New K Unveiling, as posted on the IBMWR list. Pics and German text may be found at http://www.galnedansken.com/ny_sida_26.htm.
Comments or discussion on this most interesting development?
BMW is building a completely new four cylinder machine. New not only for the Munich company but also for the entire industry. In a world exclusive, Motorrad unveils the sensational engineering of the future K-BMW.
Quicker. More Powerful. Lighter.
The Bavarians were always good for surprises. While big name
manufacturers were letting their single cylinder street bikes die
quietly, the Munich folks launched the F650 series to great success. And while all of the other motorcycle builders still grapple with the disadvantages of the telescopic fork, BMW with the Telelever introduced a new front suspension, whose undisputed advantages gave chassis builders something to think about.
With respect to ABS, catalytic converter technology, and shaft drive with Paralever the White and Blue were forerunners and already by the end of the '80s had won over their customers with these features, while the competition practiced quicker,
more powerful, lighter.
That remained so until today. Now everything changes. The new
K-BMW offers not only sensational technology, it's also quicker, more powerful and lighter. Much more powerful and faster than all BMWs before it.
The new K advances to a powerful sport-tourer of the impact of
the Honda CBR 1100 XX or even the Suzuki GSX 1300 R Hayabusa. The transversely mounted in-line four cylinder is designed for displacements from 1000 to 1300 cc, the sport-tourer from Munich is to debut probably with 1200 to 1300 cc. 160 to 170 PS should satiate even the most power hungry enthusiasts.
With a top speed of 285 kph (175 mph) and blessed with
fulminating power, the new BMW no longer has to hide from anyone. Most important. It's shaft-driven. Nevertheless, with a full tank of gas the weight is said to be below the magic 250 kg. limit, and that's with a center stand.
Typical BMW: Developed in a wind tunnel, the fairing will offer
optimal protection, rider and passenger will be quite comfortably cut off from the wind blast. The right side-mounted four into one exhaust offers a sporty exhaust note. To address safety and the environment, a new ABS system and the latest exhaust technology rounds out
Obviously, the Sport Tourer is only the beginning of a new model
series. Thus far, a spectacular naked bike is certainly conceivable.
The world hasn't yet seen something like this in a large-scale
production series. BMW is revealing that the Telelever was merely the first step to a new technology. The engineers ignite the next phase with a logically constructed package of double-wishbone front suspension and shaft drive with a flat, nearly horizontally mounted frame truss. In this way, a minimal overall height and lower center of gravity are achieved as well as a much shorter wheel base and stiffer front suspension in comparison to the current K.
Finally, the rear shock works with a progressively operating lever system. The front suspension sets standards. Two triangular links lead to a fork whose form is ideally suited to occurring forces(the path of the bending force). A pair of ball joints, which tie the fork with the links, comprise the steering axle. A scissor linkage with two likewise triangular pieces transmits the steering forces. It compensates for the up and down movements of the front spring. A vertical shock braces the lower link against the frame.
Designed in the 80s by Englishman Norman Hossack (actually a
Scotsman, raised in Rhodesia. See http://www.hossack-design.co.uk/), what advantages does this system offer? It permits a more compact frame structure in comparison to the telescopic fork, since there's no conventional steering head where extreme bending forces over the long arm of the fork act on the frame. Reinforcement alone holds the orientation of the steering yoke. The two links of the new design conduct the forces by a direct path into the frame.
Further advantage: better response behavior of the front suspension, since the stiction between the slider and fork tube of a telescopic fork is out of the picture. Also important: Neutralization of diving under braking for optimal application of ABS and nearly constant dimensions in the chassis geometry over the entire compression range of the spring.
As a whole, the double wishbone suspension is yet again superior
to the Telever. Namely, the latter is burdened also, by all
preferences, by a structural disadvantage. Trail is reduced upon
extension of the shock, the steering axis thus becoming more steeply angled, something which could lead to instability at high speeds. No big deal with Boxers or Tourers, but for ultra-quick machines rather problematic.
The single-sided swing arm is supported on the frame by a lever
system progressively operating on the shock. The arm is positioned by the short engine with stacked transmission shafts. A strut above the swing arm now braces the shaft effect. As in the case of the R1200 GS shown recently in MOTORRAD 19/2003, the pivot point of the final drive unit lies underneath the end of the shaft drive housing, which seems unusual.
The New Four Cylinder
Finally, the BMW engine developers were allowed to break with
tradition. Now the Munich folks are building an in-line
transversely-mounted four cylinder with the transmission inside the engine cases. That cuts down on engine length and weight. In order to also attain the least possible engine height, the cylinder bank is angled forward 60 degrees. At 1200 cc, the short stroke, laid out four cylinder revs to 11500 rpm, which allows for an output of 160 to 170 PS.
A ram air system feeds the huge air box with fresh intake air,
which at higher speeds can be held responsible for a power-increasing pressure effect. New fuel injection supplies fuel to the engine - of course outfitted with a three-way catalytic converter and secondary air system.
Of interest is the cam drive. A Hy-Vo chain on the right side
spins only the exhaust cam then gears set the intake cam into rotation. Valve actuation is accomplished through followers. The crankshaft, with its right web as a primary drive gear, spins forward and drives the upper transmission input shaft along with the clutch. The output shaft resides transversely below the input shaft close to the swing arm pivot. Thus, the drive shaft employing two U-joints runs with very little drive
line snatch. The generator and starter ride piggy back on the cylinders which cut down on the width of the engine.
So the new K-BMW captivates with a technological offensive. It
might not even still be called a K. The name is currently a secret.
With 170 PS (165 bhp?) and a weight under 250 kilograms (550 lbs.) the new sport tourer plays in a different league than the old K1200 RS.
New Dimensions in the Chassis.
The drawn up front of the frame holds the steering bearing and the shock under which are positioned the two longitudinal links. The clearly visible scissor linkage transmits the steering input of the rider.
The pivot point for the mounting of the final drive unit has been moved to the bottom side of the single-sided, two jointed swing arm. This allows for an over-lying strut to compensate for the shaft effect.
Pg. 4, bottom:
Two wishbone linkages with the help of two ball joints position the fork-shaped wheel carrier. Geometric dimensions such as rake and trail change only minimally as the spring compresses.
The first transversely mounted BMW engine has cylinders angled sharply forward which allows for a lower center of gravity and a compact frame.
Pg. 6, top:
The two-jointed single-sided swing arm provides room for a close-fitting exhaust cannister and consequently the basis for a narrower silhouette. The vertical shock with hydraulically-adjusted preload is no longer directly linked to the swing arm but through a lever system which provides for a progressive spring rate.
Pg. 6, bottom:
A silent Hy-Vo chain on the right side drives the exhaust camshaft.
This saves having the additional crankshaft bearing of a centrally
driven design. Gears set the intake camshaft in motion. The intake ports run in a straight line nearly vertically from above for