New Boxers Break Cover!
NEW BOXERS BREAK COVER!
ROUNDUP
DESPITE THE DEBUT OF the exciting new 160horsepower, inlineFour-powered K1200R and S, there is no doubt that BMW remains faithful to the Boxer Twin, the engine upon which the German manufacturer built its considerable legend.
For proof, look no farther than the all-new R1200RT and ST. Spy photos of both bikes surfaced at the end of last year, forcing BMW’s hand to the point that it pushed the public debut of the touring-oriented RT to the last big event of the year, December’s Bologna Motor Show, while still keeping the more sporting ST under wraps as best it could.
The R1200RT is, of course, absolutely fundamental in the Boxer model line. The core of the bike is the new 1170cc engine, a hopped-up version of the one powering the R1200GS. Claimed output is now 110 horsepower at 7500 rpm, making it the first production Boxer Twin to soundly break the 100-hp barrier. Torque is a healthy 85 foot-pounds at 6000 revs. Throttle bodies and valve sizes are the same as on the GS (36mm inlet and 31mm exhaust), but higher volumetric efficiency is achieved through use of a bigger, freer-breathing airbox and larger-diameter intake runners. In addition, the cam profile is slightly more aggressive. But most important is the solid boost in compression ratio to 12.0:1, a impressive value for a bigbore, air-cooled engine.
Teamed with a new slickshifting six-speed transmission, the RT should offer a performance level similar to that of the present longitudinal-Four-powered K1200GT.
The RT is much lighter than the old RI 150RT, dropping some 44 pounds in the redesign that features many of the lightweight GS components, including the Paralever rear suspension and similar chassis construction. Curb weight, ready to go with the 7.1-gallon (!) tank topped off (but no side bags, which are a must on any RT), is now a much more acceptable 570 pounds. This promises improved handling, further enhanced by the revised Telelever front end. This new unit is more rigid and features less variation in its steeper 26.7-degree rake and 4.3-inch trail as the wheel moves through its travel, as compared to the still-available R1150RT’s 27-degree/4.8-inch unit. Wheelbase remains 58.5 inches.
The natural question is why didn’t BMW adopt the new and much more efficient Duolever front end developed for the K1200S? The word from Munich is that preference was given to the Telelever for riding comfort reasons related to longer wheel travel.
Tires, wheels and brakes are all first-class, with twin 320mm Brembo front discs squeezed by four-piston
calipers, and sporty-size radiais, a 120/70-17 front and 180/55-17 rear. Brembo also did the lighter wheels, which contribute heartily to the overall weight reduction, but more importantly reduce unsprung mass.
As is now typical for BMW, two adjustable seats are offered: the “low” 30.7-31.5 or standard 32.3-33.0 inches.
The smooth, R100RSinspired lines of the RI 150RT have given way to much more aggressive-looking bodywork that should offer increased aerodynamic efficiency and more effective weather protection. The fairing features a new, more powerful headlight and, right below, a large air intake, split at the center to create a visual connection
with the grill of BMW cars.
Not shown in Bologna, but sharing the same power unit and most of the rolling gear, is the new R1200ST, a sporttouring model that replaces the not-so-successful RI 150RS. With an announced curb weight below 500 pounds, this new ST sets the clock back to the days of the unforgettable R100RS. Expected to join the BMW corral early in 2006, it represents the return of a real all-around high-performance Boxer Twin, unless Munich decides to go one notch farther by developing, say, a 115-120-hp, Duolever-suspended R1200S. Now that would be the great return of the Rennsport legend!
Bruno de Prato
