Boxer engine with even more power.
BMW’s new sports Boxer benefits from the innovations
already featured on the R 1200GS. Displacing 1170cc, the
two-cylinder powerplant features four valves and two spark plugs
per cylinder, following the basic principle of the flat-twin power
unit of the GS model. But at the same time, far-reaching
modifications ensure much higher peak output than on the RT and ST
models. Particularly, modified cylinder heads enable the R 1200 S
to develop an impressive 90kW smoothly.
Power is transmitted via new, high-load-resistant connecting
rods made of extra-strong steel alloy. The camshafts, with modified
control timing and larger valve lift, now rotate in three bearings,
serving to further enhance the stiffness and precision of the
entire valve drive system. Stiffer valve springs and reinforced
rocker arms take the higher engine-speed of up to 8,800 rpm into
account - a speed never before seen in a BMW Boxer engine.
New pistons are also one of the significant changes made on the
S power unit, increasing the compression ratio to 12.5:1, marking
another record for an air- and oil-cooled power unit. This enormous
compression ratio serves to boost torque at low and medium engine
speeds, the flat-twin developing a maximum torque of 112 Nm at
6,800rpm, despite the emphasis on supreme peak power. On the road,
this means supreme engine response and muscle at all times, the
flat-twin developing its maximum output on premium plus (RON98)
fuel.
At the same time, the engine is also able to run smoothly on
95-octane fuel, thanks to its anti-knock sensors, with only a minor
reduction of power.
Throttle butterflies and intake manifolds enlarged in diameter
by 5 millimetres - to 52 millimetres - work with the modified
intake funnel to boost the cylinder charge, also increasing engine
output. Due to the large intake cross-sections, the throttle
butterfly housings feature special, progressively-acting kinematic
control, the rider’s demands for engine power being delivered
to the throttle butterflies not on a linear curve, but rather with
a variable transmission ratio.
This sophisticated and well-conceived system ensures a smooth
flow of power with superior muscle and pulling force immediately
the rider fully opens the throttle at low engine speeds.
It goes without saying that the machine’s electronic
intake manifold injection, together with the engine management and
exhaust manifolds, is specially tailored to these modified flow
conditions, the interior diameter of the exhaust gas manifolds
being increased by 5 mm to 50 mm on the new R 1200 S.
Despite its sporting character, the high-performance flat-twin
power unit offers the same running smoothness as the existing
models in the R 1200 series – a feature attributable to the
balance shaft.
The dog-shift six-speed gearbox (weighing just 13 kilograms) as
well as lightweight shaft drive have already proven their qualities
on the new Boxer generation and are now being carried over, without
requiring any modifications, to the R 1200 S.
Refined frame.
Another proven concept is the multi-dimensional frame structure
on the R models, integrating the engine into the chassis and
suspension as a load-bearing element: The R 1200 S features a
three-piece frame specially geared to the qualities and
characteristics of this sports motorcycle. The central and front
sections of the tubular frame structure are made of steel, while
the rear frame bolted in place is made up of extra-light square
aluminium tubes. The advantages of this structure are not only low
weight, but also simple and low-cost repair of accident damage at
the rear.
The passenger footrest supports, also bolted on to the frame,
come off easily in just a few moments - for example for riding the
R 1200 S on a race track.
For further information contact:
Alexander Corne
PR & Corporate Communications Manager
BMW Group Australia
Phone: 03 9264 4238
Fax: 03 9562 2799
Mobile: 0439 568 819
Email: alexander.corne@bmw.com.au