BMW K 1300 GT User Manual

Page 11

Advertising
background image

BMW

Media

Information

10/2008

Page 11

Out of the two overhead camshafts, only the exhaust shaft is driven by
a tooth chain from the crankshaft. The intake camshaft, in turn, is driven by
a gear drive coming from the outlet shaft.

As a result, only one sprocket is required in the cylinder head, helping to
ensure even more precise valve timing and keeping the cylinder head slender
and compact.

Mod fi ed exhaust valve springs and an optimised tightening mechanism
on the timing chain take the new exhaust valve timing of the K 1300 S and the
requirements created in this way fully into account.

The camshafts are positioned directly above the valves, the geometric layout
of the cylinder head ensured in this manner helping to give the drag arms the
ideal transmission ratio of 1:1, meaning that they are subject to only minimum
bending and fl exing loads. As a result, the arms are extremely light and fi ligree
in their design and construction.

The engine speed limit under regular running conditions is now 11,000 rpm
although the engine would be able to run at far higher speeds in terms of
mechanical engine loads as such. The diameter of the valve crowns, as on the
K 1200 S, is 32 millimetres or 1.26" on the intake side and 27.5 or 1.08" on
the exhaust side. In the interest of higher torque, the intake ducts are specially
machined around the valve seat rings.

High compression for maximum effi ciency.
The modifi ed shape of the combustion chambers with their fl at ceiling
guarantees very high geometric compression with a thermodynamically
favourable, largely fl at piston fl oor on the K 1300 S. With its compression
ratio of 13:1, the power unit of the K 1300 S again comes right at the top in
the series production motorcycle market, offering an ideal combustion
process and optimum effi ciency.

Dry sump oil supply.
The K 1300 S features dry sump lubrication introduced on the K 1200 S and
proven over many years – the same technology as is largely used on racing
engines. Apart from superior operating qualities and reliability even under
extreme conditions, dry sump technology quite unique in this segment keeps
the crankcase low and fl at and therefore ensures a low position of the engine
and a low centre of gravity. By leaving out the usual oil sump, the entire engine
may be fi tted 60 millimetres or 2.36" lower down than a conventional power
unit.

Advertising
This manual is related to the following products: