ENGINE / DRIVE

INTAKE SYSTEM / ELECTROMOTIVE THROTTLE ACTUATOR

The new boxer engine, used in the BMW R 1200 GS for the first time,has vertical through-flow unlike all previous standard BMW Motorrad opposed-twin engines. The advantage is that the design of the intake channel no longer depends on the camshaft control, so it was possible to realise identical intake lengths for both cylinder sides. Compared to the hitherto horizontal through-flow of the cylinder heads, the vertical through-flow permits an optimally straight intake port with a correspondingly simple chain guidance of the camshaft drive.

The new digital engine control system, the so-called BMS-X, is also used for the first time in the boxer engine in the new R 1200 GS.. Its main features are fully sequential injection, a compact layout and low weight. The Alpha/n-based engine management system with torque interface draws on a wide range of parameters. For example, it enables perfectly controlled torque output and adaptation of response to a diverse range of conditions via the electromotive throttle actuator characteristics attributed to the various riding modes. The control system is based on the volume of intake air which is determined indirectly via the throttle valve angle and the engine speed. Based on additional engine and environmental parameters (including engine temperature, air temperature and environmental air pressure), the engine control system determines individually adapted levels for injection volume and ignition timing together with stored mapping characteristics and pre-set correction functions.

Carburetion is handled by an electronic fuel injection system via a throttle valve body system with an opening width of 52 millimetres instead of the previous 50 millimetres. Newly designed, markedly raised intake air snorkels and a generously sized intake silencer ensure optimum feeding of cool intake air and thus optimum filling.

An electromotive throttle actuator system is used to control the throttle valves. Here the rider’s commands are passed on from the sensor in the accelerator twist grip to the fully electronic engine control system and converted into a throttle valve position as appropriate to the riding mode selected by means of instant electronic adjustment.

The electromotive throttle actuator in the new BMW R 1200 GS allows improved ridability and optimised running smoothness in the near-idling range since the engine control detects any differences between the two cylinders in terms of mean pressure and compensates by means of selectively adapting the throttle valve angles. Furthermore, in conjunction with the optional ASC and riding modes, different throttle response characteristics can be set (soft, optimum, direct) according to the intended purpose. Much improved controllability has enabled a reduction of twist grip angle from 85 to 70 degrees. Another advantage of this technology is the realisation of a cruise control function as a comfort option. This is the first time electronic cruise control has been available for a BMW GS as an optional feature for the R 1200 GS, making long motorway journeys more comfortable, for example.