BMW K 1300 GT - Manual (Page 13)

BMW
Media
Information
10/2008
Page 13
into the cylinder head make the usual pipes superfl uous, with all remaining
hoses leading to the radiator being kept extremely short. And with the engine
requiring only two litres of coolant, the entire structure again helps to save
weight.
The patented radiator carried over from the K 1200 S is trapezoidal in
shape and bent in its contours. Again helping to improve the centre of gravity,
the radiator is fi tted at the front of the motorcycle beneath the fairing. Through
its high standard of effi ciency and aerodynamic optimisation of the fairing
and fl ow conditions, the radiator requires a relatively small surface of only
920 cm² to reliably dissipate heat under all conditions. A further advantage
is that the integrated thermostat keeps the warm-up periods very short. And
last but not least, the dirt protector fi tted in front of the radiator is likewise
optimised for perfect aerodynamics.
Optimum arrangement of all ancillary units.
To keep the engine as slender and compact as possible, the electrical
ancillaries and their drive units are fi tted behind the crankshaft in the open
space above the gearbox. The alternator, in turn, is driven by the primary
gear on the clutch, developing maximum output of 580 W and maximum
electric power of 50 Amps. The pre-shaft starter is connected to the
engine by a freewheel drive unit operating on the alternator drive gear.
Power transmission – reinforced multi-disc oil bath clutch,
optimised cassette gearbox and HP Gearshift Assistant.
For the fi rst time in the history of shaft-drive BMW motorcycles the
predecessor to the K 1300 S, the K 1200 S, came with a multi-plate oil bath
clutch with friction plates measuring 151 mm/5.94" in diameter as well as
a gearbox integrated in the engine housing by angular drive.
Given the compact dimensions and the concentration of masses ensured
in this way, this confi guration continues to offer sign fi cant benefi ts and is
therefore also featured in the new K 1300 S. The clutch has however been
upgraded through optimised linings and mod fi ed plate operating springs
to the higher power and torque of the engine. At the same time dosage of the
clutch, the operating force required and the engagement travel of the clutch
have also been optimised by increasing the size of the slave cylinder from
32 to 34 millimetres (1.26 to 1.34").
In designing and laying out the gearbox at the time, BMW did not take
the usual approach. Instead, the gearbox was conceived as a separate unit
for subsequent installation, a so-called cassette gearbox. This concept
comes straight from motorsport, where it allows parts to be exchanged quickly