1974 BMW R90/6 - 7-Page Vintage Motorcycle Road Test Article

Description

1974 BMW R90/6 - 7-Page Vintage Motorcycle Road Test Article
Original, Vintage Magazine article
Page Size: Approx. 8" x 11" (21 cm x 28 cm) each page
Condition: Good
Bavarian Motor Works has been around
for a long time making motorcycles, cars,
and airplanes (The BMW logo is based
on an airplane propeller.), among other
things. Far years their motorcycles have
been considered the epitome of reliability,
comfort, and elegance. But more recently,
without sacrificing its reputation for civil-
ity. the West German marque has been
cultivating a sporting image for its motor-
cycles.
One of the results of BMW’s change
in attitude is an increasing use of their
machines as sporting motorcycles. More
BMW cafe racers and production road
racers are appearing on the scene all the
time.
For the past few years BMW has been
active in local and national championship
road racing. Their record on the national
circuit hasn't been spectacular, but their
West Coast rider, Reg Pridmore. has
dominated California open class produc-
tion road racing to the point that when
he’s present with his 750 BMW. the only
question is who will finish second. At the
two production races at AMA nationals
last year (Laguna Seca and Pocono), Prid-
more brought the BMW home third be-
hind factory Kawasaki riders.
Another result of BMW’s sports orien-
tation was the addition of two new 900cc
models to the top of their line: the R90S,
a cafe racer, and the subject of this lest,
the R90/6.
THE BIKE: The basic BMW layout-
that is. the horizontally-opposed flat twin
engine, utilizing a driveshaft—is currently
unique to BMW in this country despite
its use in the past by Marusho. Zundapp,
and Ural, among others (although Honda
has been experimenting with a shaft-drive
flat four).
The engine-transmission unit looks
huge and heavy, but its appearance is
deceiving. Much of the room inside the
cases is taken up by a large airbox. and
the illusion of bulk is added to by the
horizontal cylinders which protrude out
into the airstream, thus keeping cool. The
engine is only about 29 inches wide, but
11 inches on each side are taken up by
the cylinder and head. Because the crank-
shaft is set parallel to the direction of
travel and the crank throws are offset, the
cylinders are offset—the left one is slightly
ahead of the right.
The engine is basically a bored-out
600cc BMW. The 70.6mm stroke is com-
mon to the entire BMW line, and the
R90/6 has a bore of 90mm. Pushrods
operate overhead valves, and the 180-
degree crankshaft keeps the pistons op-...
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