Gone in a cloud of blue smoke
The 70s was all about the Japanese outdoing each other at every opportunity. Usually we think of the superbikes as the battleground for this war, but things was just as hot further down the capacity song sheet. At 17 you could ride a 250, and the competition to create the fastest quarter-litre machine was no less than that to have the fastest Superbike.
It worked very much like your first bank account and once you had your chosen mount they decision to change brands was not taken lightly. From the first moped to the next stage, manufacturers fought hard to get your vote and Suzuki were among the best at that campaign, in the process bringing us some of the finest small capacity machinery of the period.
Suzuki and Yamaha went down the two-stroke twins route, and were neck and neck all of the way, with both claiming they had the 100mph barrier well and truly licked, seemingly with every incarnation of their respected models. The GT and RD models were evenly matched for the best part of 7 years, despite using different technology to achieve this, Suzuki sticking with the old style piston port engine, while Yamaha used power sapping reed valves. Despite the latter’s claims of boosting low down power because of the reed valves, in actual fact the GT250 has equally amounts of torque, and across similar rev range too, bringing into question the effectiveness of the Yamaha design in all but environmental issues.
These days, the Yamaha RD250 and 400 have become the desirable 70s stroker machinery to own and restore, but the GT is still a great bike and easily the equal of the brigade from the tuning fork brand. Arguable, the GT series is the most handsome of the quarter litre bunch, the Suzuki still exudes cleaner lines and looks more lithe too, and it could be argued that the T20 design was a large part of the inspiration behind the Yamaha twins in the first place. Internally the engines are very similar, so much so that to the untrained eye they look the same, and yet the Suzuki design pre dates the Yamaha one by a good few years. Finding parts to restore a GT could prove challenging, but not impossible as the model was sold all over the globe and many parts, like chrome mudguards etc, were used on other models, so its a case of doing a little home work and scouring the web and breakers.
In use, the GT feels much lighter on its feet than the equivalent RD and far more agile than any KH250 Kawasaki or CB Honda. The bike is compact and relatively easy to move around although it does have a 10mm longer wheelbase than the RD from the same period, braking isn’t as sharp either but is still efficient enough, although rumours abound of notoriously patchy braking in the wet; this was deemed to be so bad that early GT’s even came with a sticker attached to the fork leg proclaiming so.
Get really moving and the Suzook doesn’t hold a line as firmly as the equivalent RD, the Yamaha chassis shares much of its design with the early TZ race bikes and this pedigree is a hard act to beat. In contrast, the GT tubework owes a lot to its 60s heritage and never really moved into the next decade, the front and rear end definitely have minds of their own, especially when trying to change direction at speed. In normal use however the Suzuki is well behaved and compliant to its riders wants, the wide bars fitted as standard allow a good deal of control over the front end.
With a decade of development behind it, the twin cylinder power plant is a well-sorted design, there is little usable power to be had below 4000rpm, while every thing worth having is squeezed in above this figure, but the step up into this area isn’t aggressive as one might imagine. The transition is relatively smooth and calm, the negin just hops up onto the pipe and away you go, leaving a big cloud of blue behind you, the do-gooders of today would have a fit at the thought of the damage it was doing to the ozone.
The revisions made to the gear ratios in the fist few gears help the engine out a good deal in this respect and those often used, mid-box ratios keep the engine singing away without the need to dip the clutch and get it spinning up again when the revs drop down. Maximum power is to be had at 7500rpm and this peak is felt quite clearly through the seat of the pants, the engine will rev on, as most strokers will, but there is little to be achieved by doing so. Torque levels are high for such a dated design, the GT A spec engine produces a creditable 23ft-lb within a stones throw of the peak horsepower, once again vindicating Suzuki’s decision to let the pistons control the inlet timing. Overall, the GT250 A is a superb machine, often underrated and almost forgotten in 70’s history, the larger Suzuki triples, and the X7, stealing most of the limelight from the period.
Suzuki GT250A Model history
The Suzuki success story really started in 1965, many years before the GT range. The T20 “Super Six” arrived to shock the world and is ranked as the machine that effectively started the ruined the British bike industry, thankfully it proved popular and sold very well. It was light, relatively powerful and fast, faster in fact than machines double the capacity, the specification was also very high, it had a 30 hp two-stroke engine, automatic lubrication, six-speed gearbox, rev counter and a twin leading shoe brake at the front. In reality, the 100mph top speed that was claimed by the PR men was on the hopeful side, but 90mph plus, an impressive speed none the less, was an every day reality for the small Suzuki.
The first GT250 was built in 1971 exclusively for the Japanese market, iot was little more than a development of the T20 with its twin-leading shoe front drum brake and rounded looks. By the time the GT had appeared to the rest of the world two years later, it had grown a single, floating caliper, disc brake up front, and the unique ram air-cooling on the cylinder head. Many parts from the early T series still fitted to the new GT however and the designs were virtually identical internally.
The decision by Suzuki to stick with the “old school” piston port design, rather than jump ship to the reed valve induction was not such a bad one; a well-designed piston port engine can be both fast and torquey too. For the A model of 1976 the timing and top end came in for much revision, compression was increased and extra ports were added to the cylinders, while the later development of the original GT250, the X7, did see reed valves used in conjunction with piston porting.
Suzuki GT250 Time Line
1971 Suzuki GT250 R
The first of the GT series was launched almost identical to the T250 it was built for the domestic market only. It produced 30bhp @ 8000rpm
1972 Suzuki GT250 J
Still only built for the Japanese market the J model now looked like the GT we later received in the west.
1973 Suzuki GT250 K
The machine is released to an eager world, the wheelbase is extended by 20mm to 1310mm to increase high speed stability.
Surprisingly the new model was actually a good deal slower and heavier than the T20 of the mid sixties.
1974 Suzuki GT250 L
The black plastic headlight, replacing the metal chrome unit, was just about the only noticeable modification carried out between years.
1975 Suzuki GT250 M
Once again few changes other than minor decal and cosmetic alterations
1976 Suzuki GT250 A
The Ramair is gone forever and the crank gets an extra bearing in the centre. The carbs, now 28mm instead of 26mm, are rubber mounted too and the barrels have a wider stud spacing. New gearbox ratios for 2nd and 3rd gears make the bike a bit quicker off the mark. Pillion rests are moved from the swing arm to separate brackets mounted directly to the frame, and the chrome headlight makes a comeback.
1977 Suzuki GT250 B
Minor cosmetic changes were the order of the day, black headlight and side panels marked the only noticeable differences.
1978 (Feb) Suzuki GT250 C
This was the final GT piston port model with no changes in specification having been made over and above the B model of the previous year as around the corner was something completely different
1978 (May) Suzuki GT250EN X7
The limitations of the dated design soon became apparent and the all-new X7 model was released in the UK. Being 18 kilos lighter it was immediately faster than the old GT design and could genuinely top the 100mph barrier.
Suzuki GT250A Specifications
- Engine – air-cooled twin-cylinder two-stroke
- Capacity – 247cc
- Bore/stroke – 54 x 54mm
- Power – 32bhp @ 7500rpm
- Torque – 23ft-lb @ 6500rpm
- Carburetion – 2 x 28mm Mikuni VM28SS
- Transmission – 6-speed wet clutch chain final drive
- Frame – steel tube twin cradle
- Suspension – 33mm telescopic forks. Twin shock rear
- Brakes – 275 mm disc single piston floating caliper, 180mm single leading shoe
- Wheels – 3.00 x 18, 3.25 x 18
- Weight – 146kgs
- Top speed – 96mph
- Wheelbase – 1310mm
- Fuel capacity – 16ltrs
Suzuki GT250A Gallery
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