SuzukiXR238BO
ften loosely referred to as the RG700,
Suzuki’s steroid-laden superbike was
originally conceived in 1976 as a testbed
to advance development of the Japanese
company’s XR14 500GP contender. This
was the start of Suzuki’s mid-70s GP domination, with
Barry Sheene the first man to win the 500cc world title
for the marque in 1976, retaining it in 1977.
Barry’s first title was earned on a bike with the
classic ‘level’ cylinder configuration for its RG500
square-four rotary-valve engine. But that year Makoto
Hase and his Suzuki R&D team developed a larger
652cc version with overbored stepped cylinders and a
cassette-type extractable gearbox – both avant-garde
race features. The extra capacity initially delivered
too much power for the flimsy chassis and skinny rear
tyres of the period to handle, so it was detuned to a
less extreme 101kW (135hp) at 10,800 rpm, still the
first bike ever to deliver the coveted 1:1 hp/kg power-
to-weight ratio. It was much more powerful than any
other racebike of the day, and a lot more than the
85kW XR14. In fact, it became the first modern racer
to break the 300km/h mark when trapped at 303km/h
at Fuji Speedway in testing.
Suzuki’s view of the XR23 was as a rolling testbed
for its 500GP program so it wasn’t homologated for
World Championship Formula 750 racing, which at the
very least would have required a spurious attempt to
construct 25 street versions, as Yamaha had pretended
to do (but never in fact did) in order to make the
TZ700/750 eligible. Instead, four bikes were built and
hastily air-freighted to Britain just five days before
the April 1977 Transatlantic Match Races – one each
for Texaco Heron teamsters Barry Sheene and Steve
Parrish (riding for the British squad), plus a spare for
Bazza, and a fourth bike for American Pat Hennen.
Although it was Sheene who gave the XR23 its debut
race win, Hennen finished top scorer for the series.
Suzuki then left the four 652cc bikes in Britain for them
to race in the 1977 Superbike series, and were rewarded
with the series title for Sheene with four race wins, and
two more for Hennen en route to third.
It was a satisfactory debut season for Suzuki’s project
bike, which led to the 1978 debut of the factory’s all-
new XR22 500cc GP contender, which adopted the
same stepped cylinder format and cassette gearbox.
But it came without the ten-pound iron bar that Barry
had fitted to his bike to keep the front wheel more or
less in contact with terra firma when exiting turns!
Also for 1978, Suzuki produced an uprated maxi-
racer, the XR23A, with then-experimental Nikasil-
coated cylinders. Top speed at Fuji was now 309km/h,
though power was the same and dry weight unchanged
at 136kg, while the chassis and suspension were
identical to before, but with slightly bigger 300mm
front brakes. Again, the bikes were raced mainly in
the UK, with Hennen once again finishing top overall
points scorer in the Transatlantic Match Races. He
had apparently learnt the set-up tricks of the Golden
Shocks better than Barry, one reason for his success
alongside his equal mastery of the wheelstanding
rodeo racer’s rush of power. But it was Sheene who
retained his MCN Superbike series crown with six race
victories, after the American sadly suffered his horrific
career-ending injuries in the Isle of Man TT.
Hennen’s enforced retirement meant that there
was a spare XR23A available, and this was entrusted
to Dutch white knight Wil Hartog for the rest of 1978,
culminating in his beating Barry to win the final round
of the MCN Superbike series at Brands. After this,While the XR238B was a
handful, Suzuki also made
a full-size RG750 in the
winter of 1976/77. But
its 112kW was too much
for the drive chains and
tyres of the times and the
project was dropped