Shiftcam - BMW R 1250RS Rider's Manual

ShiftCam

Principle of ShiftCam
function
The motorcycle is equipped with
the BMW ShiftCam technology -
a technique for varying the valve
timing and the valve stroke on
the inlet side. The centerpiece
of this technology is a one-piece
inlet trip camshaft that has two
cams per valve to be actuated:
one for partial load and one for
full load. The partial load cam
has been developed with re-
gard to fuel economy optimiza-
tion and smooth running. The
partial load cam reduces both
the control times adapted for
this purpose and the inlet valve
stroke. Furthermore, the inlet
cams for the left and right inlet
valve differ in stroke and angle
position when the partial load
cam is activated. This causes a
staggered opening of the two in-
let valves, which have different
widths. The advantage is that
the fuel-air mixture flowing into
the combustion chamber is more
strongly swirled and more effec-
tively burned. Overall, this results
in optimal fuel efficiency and no-
ticeably improves the smooth-
ness of running. The full load
cam is optimized for performance
and releases the maximum inlet
valve stroke. In order to vary the
valve timing and the valve stroke,
the inlet camshaft is shifted ax-
ially. For this purpose, the pins
of an electromechanical actua-
tor mesh with a shift gate on the
inlet camshaft. This allows for
the actuation of the inlet valves
depending on load and motor
speed and, as a result, an un-
compromising symbiosis of per-
formance and low fuel consump-
tion.
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