Cycle News is a weekly magazine that covers all aspects of motorcycling including Supercross, Motocross and MotoGP as well as new motorcycles
Issue link: https://magazine.cyclenews.com/i/126662
~ Q.) ~ o .... u o (Top left) The RS is the sport model of the new BMW line. Claimed top speed is 136 mph. (Above left) The RT gets a larger fairing and saddlebags. Note stainless-steel exhaust. (Right) Front view of the RS shows combination mirrors/tum signals/hand guards. and the wind deflector atop the windshield.~ f BMW unveils KJ 00-4 series By Jack Mangus "Stepping over the threshold into a new era of motorcycle manufacture," is how BMW's marketing manager, Karl H. Gerlinger, described the release of the German marques's new K100 series of four-cylinder motorcycles. The IOOOcc watercooled, four-cylinder, in-line engines are installed longitud- 16 inallyand horizontally, a move Gerlinger said was made because "BMW's success depends to a certain ex tent on its exclusivness...one is no longer exclusive with a transversely mounted, four-cylinder, in-line engine, or a four-cylinder V engine. rhese designs are among the mass producer's standard offerings." In a week-long gathering of the world's motoring press in the French Ri\,'era town of La :apo,ule. n,l\\1 executives and engineers extolled the merits of the new motorcycles. Test rides and the discussions which followed indicate BMW has come up with a winner. While the four-cylinder bikes will not be available in the U.S. until October, 1984, they are being released to the European markets in three stages. The non-faired KlOO "basic model" will goon sale in Europe and England this month. The KIOO RS will be available overseas at the end of the year, and the RT early in '84. While no dollar prices have been announced for the American market, the bikes will sell in Europe for approximately 10 to 15% above the comparable Boxer twin models. The all-new 987cc, double overbead camshaft powerplant has a bore x stroke of 67170mm and a 10.2:1 compression ratio. It offers a claimed 90 horsepower at 8000 rpm and torque which one rider who had just completed a test ride said "begins when you sit on it." Two valves per cylinder (rather than four for "weight reduc:tion and easy maintenance") control the intake and exhaust of the fuel mixture, which is delivered by a Bosch LE-Jetronic fuel injection system. Ignition is provided by a Bosch VZ51L Digital Injection System, which reduces the ignition advance to limit engine speed at approximately 8600 rpm and switches off the injection at approximately 8750 rpm "thus avoiding engine damage caused hy false operation. " The engine is part of what BMW calls the Compact Drive System (engine, transmission and drive shaft). The horizontal position of the engine allows easy access to the spark plugs, valves and injection nozzles on the left hand side. Major engine repairs such as replacing the bearings of the crankshaft as well as pistons and connecting rods can be carried out without removing the engine from the frame. The forged steel five-bearing crank- o shaft has balance weights on se\!eG_ crank webs. The eighth and last craIlk web was designed as a spur wheel-.o drive the secondary shaft and c1utcti The longitudinally installed crant permits direct drive to the drive shalt without the usual deviations whic:h cause power loss. .Iii Contributing to the smoothness of the power delivery are two large dampers in the drive train, one in from of the single-disc dry dutch and one behind the three-shaft, five-speed gearbox. The drive shaft rotates in a "light-metal" swingarm. A universal joint at the axis of rotation has an over-size Silentbloc-type torsion damper. The 168-pound engine block is made of a light alloy and like the late model BMW twins, thecylindersdonr't have cast-iron liners. The bearing surfaces are treated with a Scanimet coating of nickel-silicon carbide. Multi-circuit forced feed lubrication provides oil supply to the crank and valve gear by a cog-wheel-driven pump. The oil pump casing also houses the coolant pump, which is also driven by the front end of the output shaft, and pumps approximately three quarts of coolant through the cross-flow radiator. At a coolant temperature of 217 degrees Fahrenheit, an electric fan located behind the radiator is switched on automatically.