American Motorcycle Dealer AMD 247 February 2020 | Page 26

BMW R 18/2 Cruiser Concept -
"The Biggest, Baddest Boxer"
Following the debut of the R 18 Mk I Concept at last year's Concorso d'Eleganza Villa d'Este in Italy in
May 2019, and the custom design concepts built for them by Custom Works Zon and Revival Cycles,
BMW has now moved another stage closer to production of its planned heavyweight cruiser with the
unveiling of a Mk II factory prototype (alongside the original) at EICMA recently.
Heritage
The R 18/2 is based around the
highest-capacity 2-cylinder boxer
engine of all time - the 'Big Boxer' - a
completely newly developed 2-
cylinder boxer engine.
BMW claims that "from a technical
point of view, the new 'Big Boxer' ties
in with the traditional boxer engines
that were synonymous with
motorcycles from Munich and Berlin-
Spandau for around 70 years, from the
beginning of BMW Motorrad
production in 1923 through to the
appearance of the air/oil cooled
successor - these were engines with a
clear design, created for optimum
reliability and ease of maintenance,
featuring logically arranged yet
powerful technology.
"With its OHV valve drive, along with
a separate engine and transmission
housing, the new 'Big Boxer' has the
same structural features that
distinguished the very first BMW
Motorrad boxer engine, which at that
time had laterally controlled valves.
The highest-capacity twin-cylinder
boxer engine ever used in motorcycle
series production is a 1,802 cc engine,
resulting from a 107.1 mm bore and
100 mm stroke.
The engine output is 67 kW (91 hp) at
4,750 rpm. The peak torque of 158 Nm
is available at 3,000 rpm, with over
150 Nm available from 2,000 right
through to 4,000 rpm - a generously
sized flywheel mass is said to produce
"exemplary running smoothness"
with the maximum engine speed at
5,750 rpm and idle at 950 rpm.
Air/Oil Cooling
The new 'Big Boxer' is air/oil cooled,
has large ribbed cylinders and cylinder
heads and weighs 110.8 kg (244 lbs)
including gearbox and intake system
and a vertically split aluminum engine
housing. Unlike the classic air cooled
2-valve boxer engines made by BMW,
the 'Big Boxer' crankshaft is forged
from quenched and tempered steel
and has an additional main bearing at
the center - necessary due to the
enormous cylinder volume in order to
prevent undesirable bending
vibrations of the crankshaft.
Like the crankshaft, the two
connecting rods with I-shaft are
mounted on plain bearings and also
forged from quenched and tempered
steel. They accommodate cast
Clearly targeting Harley-Davidson's cruiser sales, BMW's second R 18
Cruiser concept - 1,802 cc of big, bad Boxer - made its public debut at
Custom Bike Show, Bad Salzuflen, Germany in December 2019.
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AMERICAN MOTORCYCLE DEALER - FEBRUARY 2020