Page 29 - Riding On Spring

quality comes at a price of course, and the GTO/GTR was more costly than a 1971 Tri-
umph Bonneville, but, could hold its own in a drag race with it. A standing 400 Metres
in 14.6 seconds.

The GTO is full of quirky features. Once in 5th gear, a small light illuminates in the
tacho indicating that there’s one gear to go. The gears are all the way up for neutral
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a black mark on the bitumen. The gear lever can operate either side of the gearbox,
(the Americans were just changing to compulsory left-hand gear change on all motor-
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The motor is oil injected via a geared pump, automatically
metering the correct amount depending on revs, like most two strokes back then. The
rear light illuminates when the front brake activates, something quite rare in the late
60’s. The bike can be started in any gear (handy for that embarrassing moment at the
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stand next to the bike and kick it into life.

The engine has a claimed 40hp with ample torque. 5th and 6th gears have high ratios
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low for a two stroke that tops out at 7,500 revs where maximum power is developed.
Thus noise and vibration levels are reduced at highway speeds with the bonus of
reduced engine wear. This is borne out by excellent fuel usage of 22 km/litre, easily
bettering most two-stroke competitors.

The GTO isn’t perfect though. A precipitous 840mm seat height makes mounting an
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don’t help either. Best to place the bike on the centre-stand and use the pegs like
stirrups, horse mount style. They’re certainly not a small machine! Once on the bike,
another problem emerges, the high-rise pipes force the rider’s legs well apart, almost
into the birthing position. Riding long distances can be a somewhat painful experience
with bowed out legs for a few hours after dismount. The shape of that glorious tank
does give the rider somewhere to grip with the knees. The functional twin black dial
gauges also enhance the machines appearance
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On a run, the GTO emits a ‘growl’ quite unlike any other vintage two-stroke. It just
gathers up its skirt and goes without having to wring its neck for peak performance.
Both tyres are a narrow 3.25 inches, which look quite inadequate, especially when
considering the grunt available at the rear wheel.
Why did Bridgestone cease manufacturing these mighty machines? The most logical
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and that these bikes needed a major upgrade to stay competitive, something that
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hence Bridgestone’s decision. It’d take huge capital to produce a competitive four-
stroke range of machines. Selling price was another factor, high
quality demanded a high price.

I often wonder what a 2021 Bridgestone would look like today? The Japanese factories
would have heaved a sigh of relief back in 1971 when Bridgestone folded. However,
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‘Big Four’, as they retired into their secret research rooms to develop their range of
four strokes.

My Bridgestone GTO is possibly one of the last manufactured in mid 1971. It gets out
regularly on Club runs. Some say it’s sacrilege to use it, that it should reside in the
lounge forever, but NO WAY, it was built to run and run it will.

NEVILLE GRAY #3394, LM#13

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Engine – air-cooled 345cc twin, two-stroke, rotary disk valve, oil injection.
Compression ratio 9.3:1 Carburation - twin Amal VM 26 SC type Front brake - twin leading shoe
Rear brake - single leading shoe Dry weight - 157 k Fuel capacity - 15.2 litres
RIDING ON 29