REVIEW: BMW R 1200 GS

THE NEW BMW R 1200 GS FULFILS THE OLD DREAM OF THE IDEAL TOURING ENDURO:

Superiority in every respect, outstanding performance and superior comfort even on the longest tour, equally superior handling and agility for maximum riding pleasure on winding country roads and mountain passes give the rider exactly what he wants. Add to this low weight of just 225 kg or 496 lb quite unique in this class, plus outstanding chassis and spring qualities, and you can be sure to enjoy even the toughest tours on the roughest terrain.

The BMW R 1200 GS offers an unparalleled synthesis of harmony in its combination of offroad an onroad riding qualities. With its predecessor, the R 1150 GS uniquely successful over so many years, setting the standard in its segment consistently throughout its lifecycle, the R 1200 GS now takes you into a new dimension, raising the outstanding features of its predecessor to an even higher level on all important counts.

At the same time it goes without saying that the R 1200 GS continues all the traditional features and fortes so characteristic of all BMW motorcycles: First-class and extra-safe riding conditions ensured by even more stable running gear with the unique BMW Telelever for the front wheel and a newly designed weight- and geometry-optimised Paralever at the rear.

 

High-performance brakes of the highest calibre together with BMW’s unique Motorcycle Integral ABS guarantee supreme safety even in a critical situ­a­tion. Superior environmental compatibility, in turn, is ensured by a fully con­trolled three-way catalytic converter with the most advanced emission management – a technology, incidentally, which has been a natural feature on all BMW motorcycles for years.

Equipped with dual ignition, brand-new Digital Motor Electronics featuring integrated knock control, as well as further improved catalytic converters and separate oxygen sensors for each cylinder, the R 1200 GS increases the leadership of BMW motorcycles in the large-volume touring enduro segment to an even higher standard than ever before.

A further feature not to be forgotten is the maintenance-free driveshaft avoiding the need for unpleasant and time-consuming service particularly on long trips. The sophisticated new luggage system as well as the wide range of accessories available straight from the factory and tailored to the R 1200 GS also help to clearly prove that this new machine is powerfully continuing the tradition of large-capacity BMW touring enduro’s which now goes back almost 25 years to the R 80 G/S launched in 1980: This is most certainly the original straight from the inventor of this type of motorcycle, a machine once again setting the standard in this class.


New engine – even more powerful, comfortable and cleaner.

 

In its design principle and fundamental structure, the newly developed flat-twin power unit of the R 1200 GS follows the same standards as BMW’s former, proven engine. But at the same time the new power unit is a new development all-round, with fully revised and improved components. Optimisation of engine geometry and application of the most advanced calculation and simulation methods serve to reduce the weight of the engine by 3 kg or 8 per cent despite its larger capacity and wider range of functions. Engine width, in turn, is the same as before.

This is the biggest engine ever seen in an enduro so far, the increase in cubic capacity to 1,200 cc providing the foundation for superior output of 100 hp and muscular torque throughout a speed range wider than ever before in the past. The result is superior power under all conditions and in all situations – clearly a great advantage above all on difficult off road terrain, with power and torque constantly available regardless of engine speed, the gear in mesh, and the conditions facing the rider.

CRANKDRIVE AND ENGINE BLOCK – 1,200 CC AND BALANCE SHAFT TO ELIMINATE ALL VIBRATIONS.
The most important innovation featured on the basic engine block is the balance shaft eliminating any unpleasant vibrations: Despite their superior design principle with the cylinders opposing each other to provide a perfect balance of free mass forces (connecting rods and pistons moving to and fro) in their overall effect, conventional flat-twin engines cannot run entirely without vibrations. The inevitable displacement of the cylinders always generates “circulating” mass forces (that is forces not acting on one and the same level) causing unpleasant vibration the rider will feel on the handlebar, footrests and seat. The severity of such mass forces and the vibrations caused in this way increases as a function of engine size and, in particular, engine speed.

This is precisely why the engine of the R 1200 GS is the first power unit in the history of the Boxer engine to feature a balance shaft: Running in the opposite direction, the shaft carries two balance weights 180° apart from one another and exactly spaced out in size to provide a counter-force which, superimposed on the mass forces in the crankshaft, reduces vibrations to an absolute minimum. This keeps running conditions smooth and comfortable throughout the entire speed range, vibrations even being dampened in particular at low engine speeds without the flat-twin losing its bullish character.

The balance shaft itself is arranged exactly where it should be, saving space through its intelligent and elegant concept: Running in anti-friction bearings, the balance shaft is positioned within the countershaft and is driven by a spur gear from the crankshaft (1:1 transmission ratio). The rear balance weight is outside of the oil cavity and is bolted on to the shaft extending completely from one end to the other. The front balance weight, in turn, is integrated in the drive sprocket.

Like on the former engine, the countershaft again serves to drive the oil pumps and carries the sprockets driving the camshaft. The transmission ratio of the countershaft versus the crankshaft is therefore 2:1, the countershaft itself being driven by a roller chain.

The crankshaft is also a new design from the ground up – it is now even more compact in the interest of extra stiffness and the cranks themselves are even closer together (a modification made possible, internally, by the narrower counterweights). Despite the increase in lift from 70.5 mm or 2.78´´ to 73 mm or 2.87´´, this change in design helps to reduce weight by 1 kg or approximately 9 per cent. And to give the crankdrive the balance effect required, some of the counter-masses have been moved to the flywheel and the drive gear on the balance shaft.

As on the older R1150 GS, the flywheel holds the single-plate dry clutch, nut now enlarged in diameter from 165 to 180 millimetres. The clutch lining is free of asbestos and heavy metals, the pressure plate, membrane spring and gear plate being balanced individually to allow easy and convenient assembly of these components without any negative effects on running smoothness.

The structure of the pistons has been only slightly modified versus the previous engine, the new power unit featuring lightweight box-type pistons with three rings which, weighing just 410 grams, are once again a bit lighter still than the former pistons (420 grams).

The crankcase is much lighter than before, use of the most advanced computer methods together with innovative casting technology serving to optimise wall thickness as well as the stiffness and strength of the crankcase, weight being reduced in the process by 1.4 kg.

Well-conceived and effective solutions are also to be found in – seemingly insignificant – details such as the crank cavity air purge: To minimise undesirable pressure pulses within the cavity, with air pressure going up and down as a result of piston motion, a valve complete with membrane openings fitted here opens and closes the air purge outlet automatically as a function of pressure conditions in the crank cavity and at the same time provides a large air purge cross-section whenever required. This serves to reduce pressure fluctuations and air flow in the crankcase to a minimum, with an advantageous effect on engine output, internal efficiency (reduction of ventilation loss), oil foaming, and oil consumption particularly at high speeds.

MODIFIED CYLINDER HEADS AND LIGHTER VALVE DRIVE.

Maintaining their basic design and configuration, the cylinder heads have also been modified. From outside they are recognisable by their different contours with striking cornered valve covers.

The principle of chain-driven camshafts below the valve plane and the operation of valves by means of tappets and rocker arms has been maintained. The reason, quite simply, is that this design concept has proven its qualities countless times – and although it is not necessarily designed and laid out for high speeds, the concept has confirmed its qualities and reliable function even under tough racing conditions in the BMW Motorrad BoxerCup. The big advantages of arranging the camshafts in this way are the economic use of space available (width of the cylinder head) and the ease of maintenance so important both in everyday use and on long journeys (adjustment of valve clearance).

Valve diameter is up by 2 mm or 0.79´´ (intake 36.35 mm/1.43´´ versus the former 34 mm/1.34´´, outlet 31 mm/1.22´´ versus 29 mm/1.14´´). To ensure better and more efficient dissipation of heat, the outlet valves are filled with sodium. Valve duct design has been modified to match the larger valve diameters and the duct contours have been improved in their dynamic flow conditions. In conjunction with the increase in engine capacity, these modifications contribute to the 18 per cent increase in engine output 101 hp and torque85 lb-ft. As the final result of this design improvement using the most advanced, computer-aided methods, weight of the cylinder heads has been reduced by 15 per cent.

Internal oil cooling of the cylinder heads already featured on the former engine has been adjusted to the higher level of output and torque by improving flow conditions and avoiding any kind of throttle effect. Oil cooling improves the dissipation of heat from the valve rim and ensures a more consistent distribution of temperature within the cylinder head. All this contributes to the engine’s robust thermal stability and helps to ensure the high standard of reliability so typical of a BMW. And these are definitely the criteria that count when travelling full of luggage to all four corners of the globe under the most difficult conditions.
NEW ENGINE MANAGEMENT NOW FEATURING TWO OXYGEN SENSORS, MODIFIED DUAL IGNITION AND KNOCK CONTROL.

The new R 1200 GS further improves the leading position BMW Motorrad has had for years in the area of electronic engine management. The Digital Motor Electronics code-named BMS-K (BMW Engine Management System) is an in-house development tailored specifically to the requirements of a motorcycle. Fully sequential fuel injection, integrated knock control, faster processing of complex sensor signals by means of the most advanced microelectronics, compact layout and low weight are the most important features worth mentioning in this context.

The principle of indirect air volume monitoring and control by means of the throttle butterfly angle and engine speed (alpha-n control) carried over from BMW’s existing motorcycles has been further enhanced on the R 1200 GS, creating a concept referred to as torque-based engine management.

The basic parameters determining the optimum engine operation point remain engine speed and the throttle butterfly angle monitored by a separate potentiometer on each cylinder. Applying additional engine and ambient parameters (such as engine temperature, air temperature, and air pressure), engine management, together with control maps and correction functions contained within the system, tailors the injection volume and ignition timing exactly to the engine’s and rider’s current requirements. Taking so many factors into account, the system is able to control torque with supreme accuracy, adjusting engine running conditions perfectly to all relevant parameters.

Fuel is injected into the intake duct exactly as required and exactly on time for the intake cycle of the respective cylinder (fully sequential fuel injection). With one oxygen sensor being allocated to each cylinder, fuel/air composition is controlled individually in each cylinder according to current requirements. Both oxygen sensors are arranged close to the engine in the respective exhaust manifold, thus ensuring individual and even more precise emission management. Whenever necessary, the fuel/air mixture may be adjusted much faster than before, naturally with individual control and adjustment of each cylinder.

The positive results of this process are exemplary emission management, greater fuel economy, improved riding conditions, and an even finer response to the rider’s commands. Or, to put it in a nutshell, even greater environmental compatibility together with enhanced sheer riding pleasure.

BMS-K also incorporates all the functions of automatic idle speed control as well as cold start enrichment with warm-up control. An appropriate increase in idle speed while warming up is ensured automatically and exactly on demand by so-called “idle speed steppers” (controlled bypass ducts for additional air) integrated in the throttle butterfly manifolds, together with a corresponding adjustment of the fuel injected.

Featured in all BMW Boxers (with the exception of the 850-cc power units) since 2003, dual ignition has been further modified and improved in the R 1200 GS. The auxiliary spark plug is now arranged at the outer edge of the cylinder, the ignition timing of both plugs being freely programmable and possibly varying in time as a function of load and engine speed in order to further optimise running smoothness, emission management, and fuel economy. Referred to as phase shift, this adjustment process is maintained consistently all the way from part load to full load.

In practice this means different ignition timing points on both spark plugs in defined control map areas: 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 in the expansion cycle (60° at TDC). For all practical purposes this corresponds to single ignition on the central spark plug under full load.

The BMW R 1200 GS introduces a new system of knock control never seen before with these features in a motorcycle engine. Knock combustion is recognised by a solid body sound sensor matched specifically to the cylinders. Receiving the appropriate signals, the electronic engine manage­ment will take back the ignition angle (i.e., it retards the angle) and protect the engine from possible damage. Engine temperatures are also taken into account in evaluating the signals, helping to supplement the safety function.

Benefiting from knock control, the geometric combustion ratio on the engine has been increased to 11.0:1, certainly a remarkable figure for an air/oil-cooled engine with cylinders of this size. Specific fuel consumption benefits accordingly, the R 1200 GS being almost 8 per cent more fuel-efficient than its predecessor in the EU2 test cycle.

Designed for unleaded premium fuel (RON 95), the engine, thanks to knock control, is able to run also on regular fuel (RON 91) or other fuel qualities sometimes to be found in various countries, without requiring any kind of manual intervention or adjustment. Within the limits available, knock control adjusts the ignition angle automatically to the fuel on which the engine is running.

Interacting with a wide range of sensors, knock control adjusts to even the most extreme conditions and requirements, for example with the engine having to withstand extremely high temperatures and thermal exposure in desert areas. To provide this reliability, the electronic engine management adjusts engine running parameters and thus ensures supreme reliability under all conceivable operating conditions.

 

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