The Joy of Six: BMW's New Six Cylinder Luxury-Tourers

BMW's new six-cylinder luxury-tourers are poised to give Honda's Gold Wing some serious competition

By Roland Brown, Photography by Jean-Marie Guerin, BMW

"There's a German word, souverän, which means supremely self-assured," says David Robb, BMW's American-born design chief. "That's what we've tried to give the K1600GT and GTL. They have a relaxed performance that even our four-cylinder tourers can't approach." It's easy to understand Robb's confidence. Both new models have clear ties to the current K1300GT and previous LT models, but the 1649cc, DOHC six-cylinder engine they share promises to take the Bavarian Motor Works into a new era of refined performance.

When the naked Concept6 debuted at Italy's Milan Show last November, BMW spokesmen said its engine would initially power a tourer. Just eight months later we're looking at two: the K1600GT with sportier, European ergonomics, and the luxurious, laid-back GTL for the U.S. market.

That engine produces a claimed 160 horsepower at 7500 rpm, with 130 lb.-ft. of torque at 5000 rpm. And 70 percent of that torque is available from 1500 rpm. Dry weight of the complete bike is said to be closer to BMW's latest K1300GT than the old K1200LT, which would mean less than 660 pounds dry. At 226 lbs. (including intakes, clutch, gearbox and alternator) the six-cylinder engine is heavier than the 187-lb. K1300 four. But at 22 inches wide, it's roughly 4 inches narrower than previous six-pot bike engines, and barely wider than most fours. Relatively small-bore cylinders measuring 72.0 x 67.5mm help, as do the 5mm gaps between sleeves.

The DOHC, dry-sump design uses familiar BMW architecture, such as four valves per cylinder and the same 55-degree cylinder angle as the K1300, but there are innovations. Camshafts with individual lobes pressed onto a steel tube are about 2 pounds lighter than a normal casting. Though previously employed in diesel car engines, they're unique in all of motorcycling.

Throttle control is via BMW's E-Gas ride-by-wire system, which gives a choice of three modes: Rain cuts peak torque, while Road and Dynamic deliver alternative response characteristics while allowing maximum performance. All modes link with an optional, S1000RR-style traction-control system-complete with lean sensor-that is much more sophisticated than the ASC system used on previous BMW tourers.

Though the new bikes retain BMW's basic K-series layout-aluminum beam frame, Duolever front suspension and Paralever rear-chassis design differs from previous touring models. Forward-canted cylinders allow the main beams to curve inward, keeping the bike relatively narrow between the rider's knees and at the swingarm pivot. The frame is about 1.6 inches wider than the K1300's at its widest, but still narrow where the rider makes contact. It's also stiffer.

Much emphasis was placed on weight reduction. "We started with a goal and put energy into it until this was reached," said project manager Gerhard Müller. "The main frame is chill-cast, which allows different thicknesses. Then it's temperature-treated to make it more rigid. The rear subframe is aluminum-unusual for a touring bike. But careful design means it's okay to support a passenger and luggage.

"We tried to save weight at each end of the bike, to centralize mass and give handling that will surprise you," Müller continued. "We tried to make the bike very agile and manageable, even if it is big." The 120-degree crank requires no balance shaft, making the six a stressed member of the 35-lb. frame. The front subframe, which holds lights and instruments, is made of magnesium and feels amazingly light. It's made in two halves and joined by self-tapping screws, eliminating air gaps in the threads and minimizing corrosion.

Cycle parts are familiar BMW items. Optional electronic suspension adjustment via ESA II allows pushbutton tuning of front and rear rebound damping, as with previous ESA systems, along with rear shock spring rate and preload settings. BMW's Integral ABS is upgraded with an extra pressure sensor. And the electronic trickery doesn't end with the suspension.

The instrument panel incorporates a near-6-inch color monitor that gives information about functions ranging from the selected suspension settings, fuel consumption and range, to playlists created on the iPod-compatible sound system (optional on the GT, standard on the GTL). Here's a surprise: Both the speedo and tach use conventional analog gauges, though the former's numerals seem too small to read at a glance.

You'll have to wait a while to see for yourself. The official unveiling will be at Germany's Cologne Show this October, with a press launch over the winter and bikes arriving in showrooms in April or May. Prices are yet to be determined, but they won't be cheap. Still, the K1600GT and GTL look poised to make almost as big an impact on BMW's traditional touring sector as the S1000RR did on the sportbike scene this year.

Perhaps the most innovative feature is an optional adaptive headlight, which may make this the safest bike yet after dark. The standard headlight combines two halogen high-beams with a single central xenon projector beam (and reflector mirror) for the low-beam. The system uses level sensors to compensate for load, and provide reliable illumination on a straight road. The adaptive option shines the low beam in the correct place even when the bike is cornering. An S1000RR-style lean sensor works with a stepper motor, moving the xenon projector beam's mirror to suit the bike's cornering angle. From the demonstration we saw, this looks like a genuine breakthrough. It's likely to be offered along with traction control in an optional safety package.

That headlight also gives the front end a distinctive look, along with the broad, electronically adjustable windscreen. Both models are visually very similar but the GTL's handlebars are pulled further back, its footpegs are lower and further forward, and the stepped seat is one piece rather than two. A passenger backrest is incorporated in the GTL's top box. There's even a button on the handlebar to lock the saddlebags that are standard on both models, as are cruise control and heated handgrips and seat.

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