The bigger-yet lighter-touring enduro

The first concrete information from Germany is in on the newest BMW motorcycle-the R1200GS. It's new from the ground up and may surprise you as much for what is not included as for what is. Other models have a few surprises, too. Let's get to the facts...

Engine
Even if a dual-sport bike is not your style, this newest BMW will no doubt be a starting platform for future models. At 1,170cc, the all-new flat-twin engine is the biggest ever seen in a dual-sport bike. In design, though, it is very similar to the R1150GS engine it replaces. It's still a fuel injected, two cylinder, four valves per cylinder, high-cam, air and oil cooled engine. The extra 40cc of displacement over the previous 1130cc boxer come from a 2.5mm longer stroke to 73mm while the 101mm bore is the same. Valve diameter is up 2mm to 36.35mm on the intake and 31mm on the outlet.

Overall, these changes account for an 18 percent increase in power to 100 bhp and 85 lb-ft. of torque. While more powerful, BMW claims fuel consumption will decrease eight percent. Even more significant, the new R1200GS is 66 pounds lighter than the R1150GS-just 496 lbs. with a full tank of gas.

The most important innovation is the addition of a balance shaft. The R1200GS is the first Boxer engine in history to feature this. While the movement of the opposed pistons in a flat-twin engine cancel out most vibration, "circulating" forces cause some vibration, becoming more pronounced as engine size increases. In an effort to minimize these last vibrations, BMW has added a single balance shaft driven by a spur gear from the crankshaft at the same speed but in the opposite direction. The front balance weight is integrated into the drive sprocket while the rear balance weight is outside of the oil cavity. Two weights, attached 180 degrees apart from one another, are spaced out to keep running conditions smooth even at low engine speeds without losing, according to BMW, the engine's "bullish character."

With the addition of the balance shaft, some of the counter weights could be removed from the crankshaft. Despite an increase in lift from 2.78" to 2.87", the crank is more compact. A single plate dry clutch has been enlarged from 6.5" to 7.1".

Weight reduction continues with slightly lighter pistons and a lighter crankcase. A small but useful addition is a crank cavity air purge membrane. This will reduce pressure fluctuations and air flow within the crankcase to increase engine efficiency with reduced oil foaming and consumption (especially at high speed).

It's easy to identify the new engine by its unique cornered valve covers. Inside you'll find a dual ignition system, similar to that featured in all Boxers since late 2003, updated for R1200GS. The second plug is located at the outer edge of the cylinder with the timing of both plugs now being "freely programmable" to vary in time as a function of load and engine speed. Referred to as "phase shift," this adjustment process is maintained consistently all the way from part to full load. When approaching full load, where dual ignition no longer provides any benefits, the phase shift effect is so large that the spark crosses over on the auxiliary plug into the expansion cycle (60 degrees after top dead center). For all practical purposes, this corresponds to single ignition on the central spark plug.

To control the ignition, the GS has a newly developed engine management system called BMS-K (BMW Engine Management System). It monitors air volume, engine and ambient temperature, air pressure and exhaust gasses from two oxygen sensors placed close to each cylinder.

One of the benefits of BMS-K is the addition of a knock sensor. Hearing early detonation, the engine management computer can retard ignition timing to protect the engine from possible damage. While BMW recommends unleaded premium fuel, the knock sensor allows the engine to run on regular fuel. It also allows a relatively high 11.0:1 compression ratio.

The exhaust system is made up of two manifolds, a pre-silencer with catalytic converter and a tailpipe muffler. The entire system, all the way to the pre-silencer fitted beneath the gearbox is a twin-chamber configuration made of stainless steel. BMW says it used the oval shape muffler in addition to a pressure-control valve to help reduce noise while allowing a "throaty" sound.

The new GS also features a new 600W alternator, lightweight layshaft starter and maintenance-free battery.

Gearbox/Drive Train
The six-speed gearbox remains separate from the engine but has been improved. For the first time, BMW is using high-strength helical gears with smoother and more gentle gear mesh to ensure quiet and smooth shifting. The gear shafts run in ball bearings and the gears themselves in needle bearings allowing longer, 25,000-mile oil service intervals. Shifting is now done by shift rollers running on ball bearings, shift forks and shift sleeves (instead of shift gears used in the past) to ensure smooth positive engagement.

The entire drivetrain has been redesigned. Made of a cast aluminum alloy, the Paralever swing arm is lighter than before but also stiffer and stronger. With forces acting on the final drive housing now being supported above the swinging arm, ground clearance is greater than before, helping protect the swing arm even on rough terrain. The swing arm is attached at the front to the rear subframe instead of the transmission casing for added strength. The pivot point at the final drive is now lower for better geometry and strength. With the re-configured mounting, the driveshaft no longer changes in length as the swing arm moves. This helps to save weight, since the length adjustment unit formerly fitted is no longer required. The geometry also adds more dive compensation. The shaft now comes as one single piece and-like before-runs without oil in the shaft sleeve.

The visual detail of the final drive is a 50-mm hole drilled through the axle pipe of the final drive housing. The hollow axle sleeve will help dissipate heat. The signals for the speedometer and ABS are now read from a sensor directly in front of the crown wheel. The emitter wheel is no longer necessary. Its removal and lighter components help save unsprung weight. The final drive now comes with no-maintenance, lifetime oil.

Suspension
The R1200GS retains the basic configuration of all Boxer suspensions with the engine/transmission unit serving as a load-bearing element and the wheel components being bolted to new steel truss subframes. New features on the rear subframe are the special mounts for the side- and center-stand as well as the driver's footrests now being connected directly to the rear subframe.

The Telelever pivots on the engine housing, as before. It's a new, strong and light, forged aluminum component. Front wheel trail has been reduced .20" to 4.33" and steering head angle remains 62.9 degrees. The forks are now filled with a lifetime oil supply, which, with the fully encapsulated ball joints, means the Telelever is also maintenance free.

The front suspension features a nine-position adjustable spring preload shock absorber with 7.48" of travel. The rear shock has rebound damping adjustment and an infinitely adjustable spring preload by use of a hand wheel. The 7.87" of travel includes a travel-dependent damping (TDD) feature (introduced on the R1150GS Adventure). It provides a progressive damping effect as a function of spring travel, responding smoothly to small bumps while offering good protection for rough terrain.

In the quest to save weight, it's interesting to note the holes drilled into the lower fork bridge. It distributes brake fluid to the flexible steel hoses for the right and left brake calipers without requiring an additional distributor unit.

Purchasers of the new R1200GS will (according to this report from Germany) have the choice of either high-strength cast light-alloy wheels or BMW's well-known cross-spoke wheels measuring 2.50 x 19" at the front and 4.00 x 17" at the rear and running on 110/80-19" and 150/70-17" tires respectively. The five double spoke alloy wheels are new for the R1200GS.

The R1200GS is fitted with BMW's EVO brake system and optional BMW Integral ABS. The semi-linked system includes an on-demand deactivation switch when riding off-road. Brake disc diameter is 12" in front and 10.43" in the rear.

Networked Electronics
Yet another special feature of the R1200GS is the all-new on-board electric system named Single-Wire System (SWS). The basic principle is that it connects all control units, sensors and power consuming items via one single, common wire in order to form a complete network transmitting all signals and power. This eliminates the need for fuses and individual cables for each function. This could certainly factor into the bike's overall reliability.

It also allows the introduction of a high-tech instrument cluster based completely on digital technology. Incorporating the speedometer, tach and the "Info Flatscreen Display," the cluster provides information on oil temperature, fuel level, remaining range of fuel in the tank, clock and gear currently in use. Both overall and trip mileage are presented on demand and any defects are shown on the screen as a printed message. The entire instrument unit is automatically illuminated, controlled by a photoelectric cell.
For theft protection, the R1200GS comes standard with an electronic immobilizer controlled by a transponder in the key (similar to the system on BMW automobiles). An optional alarm system is also available.

Colors/Features
Colors being manufactured (but may or may not be imported to the US) are Ocean Blue metallic, Rock Red and Desert Yellow non-metallic. Two seat colors (Light Grey and Black) as well as two different colors on the tank side cover (Granite Grey and Black, soft paint) provide a total of 12 different combinations.
The new GS provides an all-new, asymmetric dual headlight unit with free-form reflectors under a clear glass cover. The oval design is distinctive and BMW claims it enhances illumination of the road. The windshield adjusts to five different angles without tools.

The 5.28-gallon fuel tank is made of extra-light and impact-proof plastic. The two plastic tank side covers come off with rapid catches. Two more side covers made of thin aluminum and a painted top cover give the tank its shape.
The new two-piece double seat offers two height levels for the rider (33.1" and 33.8"). Possibly available here in the US would be a higher and lower seat option extending the range from 31.9" to 35.0".

A new steel (for strength) tubular handlebar is tapered at each end to allow smaller diameter handles for better grip. New switches and controls have adjustable levers and still use the same BMW logic for the turn signals.

Made of lightweight plastic, the luggage rack is a new design. The removable passenger seat exposes a flat luggage space (the same height as the flat top optional saddlebags). New saddlebags (and case supports) top the list of optional extras. The left-hand case on the muffler side has a max capacity of 37.5 liters, while the right-hand case and top case hold up to 46 liters-total capacity is 130 liters. A feature first seen in the F650GS saddlebags is the single-lever that can reduce the volume (and size) of the cases by up to 9 liters.

For all the details and comparisons to the R1150GS, see the February '04 issue of BMW Owners News (BMW ON, the monthly magazine received by members of the BMW MOA). There is some important information we don't know yet, like price and what will be imported to the US. On paper, the new R1200GS looks like a winner but it's how the motorcycle handles on the street and in the dirt that will determine its success. The BMW ON will have the first ride details in the March issue. Stay tuned!