he "flying commode." The "pregnant duck." The "trussed turkey."
The "plumber's nightmare."
These are just some of the
less-than-complimentary nicknames bestowed on Suzuki's 652cc
XR23B, the ultimate version of the cubedup rotary-valve square-four ultrabike
which the Japanese factory's chief designer,
Makoto Hase, concocted in the mid-70s,
complete with its distinctive fat exhausts
wrapped around the twin-shock rear end.
Often loosely referred to as the RG700,
T
56
JULY 6,2005 • CYCLE NEWS
Suzuki's steroid-laden superbike was more
properly known by its XR23 factory designation and was initially conceived by Hase
in 1976 as a rolling' test bed to advance
development of the company's XRI4
500cc Grand Prix contender, which had
demonstrated its potential the previous
year by winning the Dutch TT in the hands
of Barry Sheene, thus delivering proof that
Suzuki had come of age as a motorcycle
manufacturer after previously dominating
the 50cc and I25cc tiddler GP classes in
the I960s. This was the prelude to Suzuki's
mid-70s domination of 500cc racing, with
Sheene becoming the first man to win the
500cc World title for the marque in 1976,
then doubling up the following year in a
class whose grids were now dominated by
the company's rotary-valve square-four in
customer RG500 form, earning it the title
of the "modern-day Manx (Norton)."
Suzuki's, and Sheene's, first 500cc
World title was earned with the 76 version
of the XRI4, which for the first time
adopted what would come to be the classic 54x54mm "square" cylinder dimensions
for the class, but it still retained the same
level cylinder configuration for its squarefour rotary-valve engine as its short-stroke
75 predecessor. But during 1976, Hase
and his team of Suzuki engineers developed a larger 652cc version of the motor,
which for the first time featured stepped
cylinders and a cassette-type extractable
gearbox - both features which would
remain part of the design until its replacement a decade later by the RGV500 V-four.
Obtained by boring the engine out as far as
it would go, with 62mm-diameter pistons,
