and photos courtesy
of BMW AG
BMW Announces the K1200S
High-Performance Sports Bike
BMW K1200S Sets
World Speed Record
K 1200 GT Sport Touring version of the K 1200 S
It's finally here!
The time for speculation is over. Now it's official: the K 1200 S
In motorcycling as in boxing, the unexpected moves
are sometimes the most effective. BMW, successful
for more than eight decades with reliable, durable and,
well... sensible motorcycles, has unleashed a most
unexpected performance vehicle into the hands of
sporting enthusiasts the world over.
BMW first ride impressions
The new 2005 K 1200 S is a synthesis of everything
BMW has learned from decades of motorsport success and
detailed motorcycle development. It is a sport model
without precedent and devoid of compromise. The K
1200 S exists to define maximum performance with
unprecedented sophistication and technology-enhanced
safety measures. Yes, it accelerates aggressively
enough to take your breath away-thanks to an all-new
four-cylinder engine with 167 horsepower-but also
embodies everything BMW has learned about rider comfort
No Overnight Success
For BMW to step into a new realm of performance
required extensive research and development. The K
1200 S is the result of a five-year process that first
looked at the overall concept of a high-performance road
bike and considered several options along the way to
building a sophisticated aluminum-frame sporting model
with an innovative inline-four-cylinder engine.
Central to the development of the K 1200 S was the
realization that the inherent benefits of BMW's
customary designs - the opposed-twin Boxer engine and
the longitudinally mounted four-cylinder in the K series
- could not be ignored in the new model. And a
primary advantage of BMW design has been the
centralization of motorcycle mass and, particularly, the
desire to keep the overall center of gravity low.
Such a philosophy ensures that the motorcycle is
highly maneuverable and yet remains completely stable
and composed even while traversing rough roads.
Furthermore, a low center of gravity makes the
motorcycle more comfortable for riders with shorter
inseams. Take two motorcycles of equal weight, and
the one with the lower center of gravity will feel,
subjectively, much lighter and confidence inspiring.
With the decision made to develop the K 1200 S with
as low a center of mass as possible, BMW engineers set
to work creating inspired and uncommon solutions.
Driven by New Engine Technology
BMW's famed Boxer engines have continued along an
aggressive development path to their current state of
the art, but it has been recognized that an inline
arrangement is the best overall compromise for a
four-cylinder engine when maximum performance and
lightest weight are the primary goals.
BMW chose a novel arrangement for the K1200S's
four-cylinder engine. The liquid-cooled
four-cylinder powerplant is aligned across the frame-a
significant departure from the K-Series standard of a
longitudinally biased configuration. Not only has
the new engine been designed to be as compact as
possible, but in an effort to optimize the motorcycle's
overall center of mass and fore/aft weight distribution,
the cylinder bank is leaned forward 55 degrees from
By canting the cylinder block forward, the
four-valve-per-cylinder head rides much lower in the
chassis, moving the engine's center of mass forward and
down, which helps improve steering response and
front-wheel traction on such a powerful motorcycle.
It might be enough for some manufacturers to come up
with this unique arrangement, but BMW has pushed the
advantages even further. The space created by
canting the cylinder block allows the transmission
shafts to be stacked vertically to help reduce overall
engine height and to better centralize the powerplant's
A direct gear drive from the crankshaft to a wet,
multiplate clutch minimizes driveline losses, while the
compact nature of the engine allows for the use of a
shaft final drive without compromise. The
high-strength crankshaft is forged out of a single piece
of steel, and employs 8 counterweights for excellent
vibration control. In fact, the K 1200 S combines
a superbike's power with a touring bike's low
maintenance requirements, all at a remarkably low
weight: The engine and transmission weigh less
than 180 pounds.
Racing Experience Informs the Design
In an effort to maximize power output, BMW turned to
its history of racing experience for design elements of
the K 1200 S's 1157cc engine. The goal was not
just class-leading power but compactness and low weight.
To reduce engine dimensions, the K 1200 S employs a
unique water pump arrangement. The lightweight
pump is driven directly from the intake camshaft on the
left side of the motorcycle. This location permits
the pump to have very short and efficient connections to
the cooling jacket in the cylinder head and to the
radiator mounted below the front section of the frame.
Reducing the length of hoses saves weight and improve
Other techniques are used to reduce engine weight and
size. For example, the lubrication system employs
a remote reservoir so that the engine does not require a
deep oil sump. The result is an engine that can be
placed lower in the chassis for improved handling.
Inside the engine, the oiling system has been
tailored using BMW's motorsports experience. Using a
technology employed in BMW's famously powerful Formula 1
engines, the K 1200 S's crankshaft is lubricated by oil
pumped directly into the end of the hollow crankshaft,
where it can flow directly to the main-bearing and
connecting-rod journals without the need for a ring
groove in the big-end bearings.
This technology improves lubricating-oil flow and
strengthens the connecting-rod bearings. Finally,
dedicated oil galleries direct lubricant to the bases of
the pistons to help dissipate the high thermal loads
encountered by an engine tuned for this much sheer
Careful attention to the ancillary systems helps
create an engine that is unusually narrow, too.
For example, the camshafts are driven from a single
chain to the exhaust cam; lightweight and accurate gears
drive the intake camshaft from the exhaust camshaft.
This design element allows the engine to be narrower
overall and permits the head to be shorter front to back
than would be possible with conventional technologies.
In addition, the 580-watt alternator is driven by
gear atop the transmission case, further reducing width.
Overall, the engine, at crankshaft level, is less than
17 inches wide, closer to the current 600cc powerplants
than engines in the K 1200 S's displacement class.
The forward-angled cylinder bank reduces the engine's
center of mass but carries other significant benefits as
well. For instance, the intake tract can be very
straight, which improves intake efficiency and power,
and reduces emissions. On the other side of the
cylinder head, the K 1200 S's lightweight exhaust system
can be straighter, also for improved efficiency.
Twin Balance Shafts for Ultimate Smoothness
Inline-four-cylinder engines have characteristic
vibration but the K 1200 S powerplant uses a technology
also explored in the new R 1200 Boxer engines to make it
inherently smooth. Twin balance shafts are gear
driven by the crankshaft at twice the crankshaft speed
and employ rubber bushings to reduce transmission of
noise and vibration. These balance shafts reduce
transmission of second-order vibration from the engine
to the chassis and, therefore, to the rider, who will
experience four-cylinder serenity as never before.
The K 1200 S's four-valve-per-cylinder head uses
modern Formula 1 architecture, with a narrow valve angle
- 10 degrees for the intake valves and 11 degrees for
the exhaust valves, from vertical - to ensure a flat,
efficient combustion chamber. This fast-burning
chamber can then support a high compression ratio -
13.0:1, compared to 11.5:1 for the K 1200 RS - that not
only maximizes power but helps reduce emissions and
improve overall thermal efficiency. In this case,
you can have power and low emissions in one package.
The K 1200 S's 16 valves are operated by lightweight
rocker arms directly on the camshafts, with the cams
displaced slightly outboard and down from the valve
themselves. This configuration reduces the size of
the cylinder head and permits longer valve stems for
increased rigidity and durability. The lowered cam
position also makes the engine shorter, front to back,
considering the 55-degree angle of the cylinder block
from the vertical.
Uncommon Partners: Shaft Final Drive,
Transferring power from the crankshaft to the rear
wheel is a new-design six-speed transmission using
stacked gears in a "cassette" configuration, installed
into the cases from the side. This racing-inspired
technology is not only lighter than conventional layouts
but considerably more compact. The straight-cut
gears are stronger than other types so they can be kept
slender, for an overall reduction in width.
Sportbike enthusiasts have had to live with the muss
and fuss of a chain final drive. No longer.
The K 1200 S uses an updated version of BMW's highly
regarded Paralever system, which employs a simple spur
gear from the transmission output shaft. Although
there are inherent efficiency losses with a dual-gear
shaft system - one gear is used between the engine and
the front of the shaft and another at the rear wheel -
BMW has found from studying the real-world effects of
chain deterioration and lack of maintenance that the
actual losses are extremely small. Compared to
previous shaft-drive systems, the K 1200 S's is far
lighter and more compact.
Intelligent Engine Management
BMW's BMS-K (BMW Engine Management with Anti-Knock
Control) Digital Motor Electronics debuted on the R 1200
GS and is implemented in a highly developed form on the
K 1200 S. It features fully sequential
cylinder-specific fuel injection with integrated
anti-knock control and a new technology called alpha-n
momentum-based engine management.
This innovation takes a range of parameters into
account and uses indirect determination of air volume as
a function of the throttle butterfly angle and engine
speed. Fuel injection is fully sequential; each
cylinder receives a jet of fuel precisely during the
intake stroke. In addition, the fuel delivery
system features variable-pressure technology- this
reduces the need for a fuel-return pipe; the engine
consumes all the fuel delivered to the injection rail.
This system also allows fuel pressure to be varied
for optimum fuel/air mixture, which is then checked by
an oxygen sensor in the exhaust manifold. The K
1200 S's BMS-K also employs an automatic idle speed
control. To ensure maximum output, the throttle
bodies measure a generous 46mm across and use a patented
progressive linkage to improve low-speed throttle
An important part of the BMW-K engine-management
system is an integrated anti-knock system, which allows
the engine to use a very high (13.0:1) compression ratio
for optimum combustion efficiency without the worry of
damaging detonation. Two sensors - one positioned
between cylinders 1 and 2, the other between 3 and 4 --
detect knock and cause the BMS-K computer to retard
ignition timing. As a result, this high-output
engine can be run on a variety of fuels without damage;
the main difference is the power output, which is
greater with high-octane fuel.
And A Radical New Suspension System
BMW remains at the forefront of new suspension design
with the K 1200 S. Using a concept developed by
British inventor Norman Hossack in the 1980s, BMW then
created a front-wheel suspension -- called Duolever --
with perfect kinematics. Conventional front
suspension designs have involved a compromise between
comfort and handling plus varying degrees of anti-dive
effect when applying the brakes.
The modern Duolover system employs two longitudinal
arms in parallelogram arrangement. A rectangular
pivot made up of two almost parallel longitudinal arms
turning within the frame allows free wheel motion.
A bearing is housed in a light alloy casting and is
connected to the longitudinal arms by two ball bearings.
In this way, it can convey steering forces through an
assembly resembling a pair of scissors. A central
spring/damper assembly on the lower longitudinal arm
provides the suspension and damping effect required.
The primary advantages of the Duolever design is that
wheel stroke follows an almost straight line, with the
bike's overall steering rake (castor) and wheelbase
changing only minutely regardless of wheel travel.
This consistent chassis geometry allows optimum
stability while retaining agility. In addition,
the low friction of the longitudinal arms means that
wheel response remains smooth and consistent even under
high lateral forces or when subject to severe bumps.
Because of this, the spring and damping rates can be
kept firm without sacrificing comfort. This is the
ultimate goal: Combine comfort and stability, stability
and agility, high-load absorption and small-bump
compliance. All at once.
In addition, the Duolever, like the Telelever A-arm
system used extensively in the BMW line, transfers
suspension loads into the frame, so that the overall
stiffness of the frame is enhanced. And it's
light: Weighing just 30.2 pounds, the entire Duolever
system is 10 percent lighter than a comparable Telelever.
The Duolever system also provides effective anti-dive
action when braking. Because of the Duolever's
geometry, forces acting on the front wheel when applying
the brakes cause virtually no compression of the spring,
so the chassis attitude remains predictably flat.
However, the dynamic distribution of wheel load gives
the rider important feedback on braking effort similar
to that of a conventional fork.
Full Electronic Control
With the K 1200 S, BMW introduces electronically
controlled springs and dampers. Riders of
high-performance sportbikes are accustomed to reaching
for tools to make fine suspension adjustments, but they
won't have to do any such thing on the K 1200 S.
Using high-quality gas-pressure shocks and coil-over
springs front and rear, the K 1200 S's suspension can be
ordered with an option called ESA -- Electronic
This feature allows the rider to simply press a
button on the handlebar and affect a change in spring
and damping rates front and rear. The rider sets
the load configuration - solo, solo with luggage, or
rider with passenger and luggage - and the system
determines the appropriate spring settings
automatically. In addition, the rider can choose
three riding modes - comfort, normal or sports - and the
ESA will adjust the damping rates to suit. The
damping modes can be changed on the fly, while the
spring settings must be made with the bike at a
standstill. The inherent benefit of the K 1200 S's
ESA is that the damping rates are adjusted equally and
suitably for the riding style.
Innovative Technologies Supported by and Advanced
For the K 1200 S, BMW embraced new chassis
technologies and frame designs with the aim of further
reducing the bike's center of gravity and dramatically
improving chassis rigidity and therefore dynamic
stability. The frame is made up of a special
construction of aluminum alloys. The side elements
are pressure-cast aluminum notable for its very high
strength-to-weight ratio and easy manufacturability.
Joining those elements are alloy extrusions and
die-cast members welded by a high-precision automated
machine. All together, the frame weighs a mere
25.4 pounds. Because the counterbalanced engine
does not vibrate like a typical four-cylinder, it can be
mounted solidly to the frame - no rubber isolators are
necessary. In this way, the frame is further
strengthened by the engine structure.
And it's not just the materials that break new
ground. Because the K 1200 S's engine has been
designed to lay forward, the main frame members could
then be tilted toward the horizontal as well, which
provides two crucial benefits: the overall center of
gravity of the engine/frame unit can then be lower, and
with a straighter path from the front suspension pickup
point to the swingarm pivot, the frame could be more
rigid without suffering a weight penalty.
Impressive Brakes With Adaptive Anti-Lock Control
BMW's acclaimed EVO brake system is standard on the K
1200 S. Integral ABS is available as an option.
Disc diameters in front are 320mm with a single 265mm
disc at the rear. The K 1200 S includes BMW's
Partial-Integral adaptive braking system. Both
brakes -- front and rear -- are activated whenever the
rider pulls the handlebar-mounted lever, but only the
rear brake is activated by the foot pedal. BMW has
continued to develop the EVO ABS system and for the K
1200 S, the technology has been refined once again to
take full advantage of the bike's peerless sporting
These powerful brakes work through new-design wheels
that are light yet strong. They carry traditional
sportbike-sized tires - a 120/70ZR17 in front and a
large-footprint 190/50ZR17 at the rear.
The ergonomic design of the K 1200 S reflects its
aggressive performance but retains the traditional BMW
long-distance sensibilities. The frame is kept
thin between the rider's legs because of the
canted-cylinder engine design. Partly because of
that, the rider's footpegs can be mounted low, for
increased legroom. Despite this, the K 1200 S can
be leaned at an angle of more than 50 degrees.
Cutting Edge Electronics
The K 1200 S breaks so much new ground for BMW that
it would be easy to lose sight of the totality of the
motorcycle's forward-thinking technologies. For
example, like the R 1200 GS, the K 1200 S employs BMW's
single-wire, CAN-bus electrical system, which greatly
reduces the number of wires used in the main harness and
dramatically reduces weight and complexity. Part
of the CAN-bus is a new fully electronic instrument
cluster featuring Info-Flatscreen for additional system
information available at a glance.
Options and Accessories
A comprehensive list of BMW options and accessories
are available for the K 1200 S. These include:
Anti-theft warning system -
Heated handgrips - Low-profile seat - ABS Brakes
Accessories: BMW Navigator II GPS
moving-map system - Center stand - BMW adjustable side
cases - Tank Bag