BMW K 1300 GT - Manual (Page 8)

BMW
Media
Information
10/2008
Page 8
The engineers at BMW Motorrad have skilfully eliminated the disadvantage of
a relatively high centre of gravity on the engine inevitable with a conventional
four-cylinder concept in typical BMW style. Precisely for this purpose,
therefore, the cylinder axis of the K 1300 S power unit, as on the former
model, is inclined to the front at an angle of 55°. This not only lowers
the centre of gravity, but also helps to ensure a well-balanced distribution
of weight – an essential factor particularly for the sporting rider crucial
to a precise feeling on the motorcycle and clear feedback.
A further advantage is that the spec fi c angle chosen on the engine provides
ample space for a free-fl owing intake system directly above the engine and
allows ideal confi guration of the frame profi les according to the fl ow of power.
This upgraded, second generation of four-cylinder power units in the 85-year
history of BMW Motorrad and the 25-year history of the K-Series fully
refl ects the traditional philosophy of BMW Motorrad to offer demanding,
unique and, at the same time, highly superior solutions. As before, therefore,
the engine concept boasted by the K 1300 S is acknowledged as the
currently most advanced and consistent confi guration in worldwide motor-
cycle construction.
Increase in capacity to 1,293 cc by enlarging the cylinder
bore and extending engine stroke.
The crankshaft of the K 1300 S power unit, as before, is made of forged
heat-treated steel and comes with eight counterweights as well as an offset
angle of 180° traditional at BMW in order to ensure consistent fi ring intervals
Apart from the cylinder bore enlarged by 1.0 millimetres (0.39"), particularly
the increase in cylinder stroke from 59.0 millimetres or 2.32" by 5.3 milli-
metres (0.21") to 64.3 millimetres (2.53") serves to increase engine capacity
by 136 cc.
As before, the stroke/bore ratio of 64.3/80.0 millimetres (2.53/3.15")
(K 1200 S: 59.0/79.0 mm; 2.32/3.11") ensures adequate bearing journal
overlap in the interest of superior stiffness. Both the main and connecting
rod journals measure 38 millimetres or 1.5" in diameter.
The lubrication system has been carried over from the K 1200 S, with the
balance shaft bearings adapted to the new requirements of the K 1300 S.
The camshafts in the cylinder head are driven by a chain which, in turn,
is driven by a sprocket forced-fi tted on to the right end of the crankshaft.