This page is about the Suzuki GSX-S family and where it came from.
The GS750 introduced in 1976, along with the parallel-twin GS400, was Suzuki’s first large multi-cylinder four-stroke motorcycle. The GS was Suzuki’s version of what was and is referred to as a Universal Japanese Motorcycle, so common was this 4-cylinder four-stroke configuration amongst the Japanese manufacturers at the time. The 63 bhp air-cooled, twin-cam, in-line four cylinder, GS750 road bike set the pattern for the GS/GSX range until the birth of the first of the race-replicas, the 1985 air/oil-cooled Suzuki GSX-R750. The GS750 two-valve engine showed the influence of Suzuki’s long history of two-stroke design and manufacture; the new four-strokes sporting pressed together roller bearing crank-shafts universally used in two-stroke bottom ends.
The key feature of the GSX engine was the change from the common two-valve per cylinder hemispherical combustion chamber with domed piston design of the GS engine, to a four-valve per cylinder Twin Swirl Combustion Chamber (TSCC) with flat topped piston design. The TSCC design was essentially a modification of the Pent-roof combustion chamber design to which was added a slightly raised ridge running along the combustion chamber roof parallel to the gas flow of the inlet charge. This was to encourage controlled swirl of the incoming fuel-air charge in order to increase the fuel burn speed through better flame front propagation. The higher burn speed, coupled with lowered heat loss from the shallower combustion chambers created by comparatively narrow included valve angles and the flat topped piston meant that the GSX engines produced more power and torque than the same sized GS mills.
The other major difference with the first GSX engines was the move from direct overhead cam actuation of the valve by shim and bucket of the GS engines, to valve actuation via short forked rocker arms in the GSX -the valves stems and springs being located inboard from the camshafts due to the reduced included angle between inlet and exhaust valves. Apart from the heads the GS/GSX engines were of a common design.
The current range of bikes by that name are completely different designs that use derivatives of former super sports engines from the early-to-middle GSX-R series.
Among the earliest GSX models were the two-cylinder GSX 250 and the GSX 400.
These Suzuki GSX models were the evolution of the GS series of two-valve-per-cylinder air and oil-cooled four-stroke motorcycles. The first four-valve engines were produced for the 1980 model year, but retained the “GS” designation for the US and Canadian markets until the release of the GSX-R models in 1986 (1985 outside the US). These GSX engines were based on Suzuki’s “TSCC” (Twin-Swirl Combustion Chamber) engine design, and shared little with previous two-valve models. In 1999, only for the Asian market, the sport-touring Thunder GS 250 emerged. Subsequently, to be given the designation GSX in 2001. By 2005, that was then completely discontinued. The Suzuki Katana, which had the same “TSCC” engine design but, with the designation of GSX-S. Although, that had little in common with the more modern GSX-F Katanas which are, like the previously mentioned Thunder, sport-touring bikes.
The TSCC engine was once again redesigned in 1983 with the introduction of a completely new GSX 750, Suzuki’s first modern mono-shocked sportbike in both a naked (GSX 750E) and half-faired (GSX 750ES) version. Although this bike received solid reviews from testing magazines (and came to be the testers’ preferred 750 sport machine for the year), its release was an ill-timed duel against Honda’s all-new V4 engine in the form of the VF750 Interceptor.
The 1983 GSX 750ES had air-adjustable anti-dive forks, preload and compression-adjustable rear mono-shock (“Full-Floater”), disc brakes at both ends, a fuel gauge and digital gear indicator.
The bike disappeared from dealers in 1984, to be replaced with the GS 700 – a bike with a de-stroked engine and minor cosmetic differences. Minor tweaks included taller pistons and slightly differing cam lift and timing. This plus a change in factory gear ratios enabled Suzuki to produce a motorcycle with near-identical performance specifications to the GSX 750ES, even though engine displacement was 15 per cent smaller to satisfy the revised US import guidelines. These included increased tariffs imposed by the US government on all imported motorcycles displacing more than 700cc (repealed in 1988). This 50 per cent tariff was the reason behind the glut of de-stroked 650 cc and 700 cc Japanese motorcycles sold in the US in the mid-1980s – unique to the rest of the world – and is also the reason the GSX-R debuted in the US a full year later than the rest of the world. It was available as the naked GS 700E and as the GS 700ESwith bikini fairing.
This work was mostly in vain for the US market, however, as the GSX 750S Katana was completely restyled in 1984, and the GSX-R 750 was released abroad, painting a certain demise for the comparably ho-hum ES. 1984 also saw an update in color schemes for the GSX 750ES in the rest of the world, with the naked “E” being dropped in favor of the half-faired “ES” and a new “EF” model with full upper and lower sport fairings (never available as a factory option in the US).
The GSX 750E lived on for a few more years abroad, but was eventually superseded by the GSX-F series Katanas. The GSX-S Katanas were also dropped from Suzuki’s regular lineup, replaced by the GSX-R series. The GSX 1100 lived on with significant styling changes for the 1984 model year, including a full-faired 124 bhp monster of a musclebike, the GSX 1100EFE (US: GS1150EF). The larger bikes, although still sought-after as classic superbikes, were also replaced by the GSX-R and GSX-F (sold as a Katana in North America only) lineups, with significant body styling changes such as an electrically operated screen in the 1100F, upgraded suspension and braking components, and frame revisions.
The GSX 750S (US: Katana) received an updated engine for 1984, along with Suzuki’s other big-bore four-valver models. This is the engine that the first Suzuki GSX-R Series bikes were based on.
Current GSX models are powered by derivatives of this in-line, four-cylinder engine with four valves per cylinder, which is also used in the Suzuki Bandit Series up to the end of the 2006 model year. They feature a combined air/oil cooling system called SACS (for ‘Suzuki Advanced Cooling System’).
The current GSX series is produced as the GSX600F and GSX750F faired sport touring models, now in their second generations, and the unfaired, twin-shock GSX 750 and GSX 1400 models.
The bike was used to win the 2007 Endurance FIM World Championship.
The GSX650F, produced from 2008, is essentially a variation on the Bandit 650, with much the same specification and components. The additional lower fairing, however, gives it a sportier look similar to that of the Suzuki GSX-R Series(though the Bandit chassis means that it carries 110 lb extra weight compared with a GSX-R), the engine has had a small amount of remapping to encourage revs, and the suspension is tweaked. It also has a one-piece seat, unlike the Bandit.
The earlier GSX750 and GSX1200 Inazuma (GSX750W and GSX1200W) were offered in Japan and Europe for a short time besides the GSF1200 Bandit to cater for a clientele that went for a more traditional styling and a somewhat higher build quality. When they proved sufficiently popular for overseas export, they were quickly developed into the current GSX 1400.
These modern non-US GSX-models carry little in common with their early to mid-eighties cousins other than a distant ancestor in their powerplant. The GSX 1100S Katana has been reissued as an anniversary model several times for the Japanese domestic market (where the GSX 400S Katana remains a very popular model with styling straight from the early-1980s), and Yoshimura has recently released a small handful of fully re-worked factory GSX 1100S Katana models for sale, requiring potential buyers to win an essay contest before being granted the opportunity to purchase one of these bikes.
The first GSX-R of 1984 was a breakthrough model and the closest that any Japanese manufacturer had yet come to building a “race bike with lights”. Throughout the 1970s the big four Japanese manufacturers had built bikes with a similar architecture: steel double loop frames, air-cooled inline fours with either SOHC or DOHC configurations.
At the start of the 1970s two valve per cylinder heads were ubiquitous, by the end of the decade four valve heads were available on the high end bikes. The similarity of the designs across brands and years led to the coining of the term “UJM” for Universal Japanese Motorcycle, which began with Honda’s CB-750 of 1969.
These bikes were available in a variety of sizes from 350cc to 1200cc from all four of the Japanese manufacturers, and beginning in 1976 served as the basis for production-based race bikes in the American Motorcycle Association (AMA) Superbike Series. As a result of the experience on the race track it became obvious that the big UJMs were not ideal for racing. Weight was high, frames lacked stiffness and flexed in disturbing ways, power from the big motors overwhelmed the tire technology of the day.
Beginning around 1980 all four manufacturers began to modify the UJM formula in different ways to achieve performance advantages on the track and product differentiation in the market. In 1982 Honda introduced the VF series, which used a V4 rather than inline-four motor configuration. The first model year only cruiser style bikes were offered, but in 1983 the first sport bike based on the V4 became available:the Honda VFR-750 Interceptor. AMA rules for Superbike racing were changed in 1983 to decrease maximum engine size from 1025cc to 750cc. The Honda Interceptor was ready to compete in this new category. In addition to the innovative V4 engine configuration, it was liquid cooled, and it sported a rectangular tube steel frame, to increase stiffness, as opposed to the more traditional round tubes of the UJM era. The Interceptor was a breakthrough for Honda, and it won many races, including Daytona, and was the second-place finisher in the series. A year later, in 1984 the entire front row at Daytona were Interceptors and Freddie Spencer repeated his win on the V4 Honda.
In 1985 both Yamaha and Suzuki answered the challenge with their own innovations. Yamaha offered the FZ750 which was the first in a series of bikes with 5 valves per cylinder. While it was still an inline 4, the cylinders were set at a 45 degree angle, unlike the more typical nearly vertical placement common to UJMs. The frame was rectangular section steel like the Honda.
It was into this competitive environment that Suzuki dropped the first 750cc GSX-R model ready to race in the new size mandated by AMA Superbike rules. The GSX-R had the most conventional engine of the three: a four valve per cylinder, inline four – it was a clear descendent of the previous GS series of motors. Cooling was provided by what Suzuki described as an air-oil mix. Oil temps were kept low by a large oil cooler, and engine internals were designed to push the oil at pressure as a spray where it was most needed, notably the underside of the pistons. The principal designer for the bike was Hiroshi Fujiwara, a Suzuki engineer.
The frame was the most innovative aspect of the bike. Suzuki abandoned steel altogether and built the frame from welded square section aluminium tubing. To gain the rigidity they wanted, the tubes were quite large, giving the bike a unique appearance. Whereas the Honda and Yamaha were fast street bikes that could be easily raced, the Suzuki was clearly a race bike that could be ridden on the street. The seating position was the racer’s crouch, not the street rider’s semi-upright one. It shipped stock with the motor tuned to deliver 100HP, but could be easily boosted to 135 with the race tuning kit. It was the lightest of the superbikes by a good margin, weighing only 388 lbs. Styling too was aggressive and unique, with a signature full fairing holding two round headlights, starting a trend that continues on supersport motorcycles to this day.
Despite the excellence of the bike it was not able to immediately dethrone the Honda team, who won the AMA Superbike series with the VFR Interceptor from 1984 to 1988. In 1989 Suzuki did accomplish this goal. By then the Suzuki had already become the favorite of privateers, racers not backed by a factory. Its relative simplicity (compared to the V4), cost and reliability made it the obvious choice for individuals competing on their own dime. Over time it has also established an excellent record in endurance racing winning the Bol’d’Or 12 times between 1993 and 2011.
The 750cc GSX-R of 1985 was followed by an 1100cc version in 1986. If the 750cc bike was a fast and capable race-bike for the street, the 1100 was an exercise in raw power and excess. A bit heavier than the 750, at a claimed 435 lbs, but with considerably more power (130 hp stock) and torque. Previous to both of these models, 1984 Suzuki released the GSXR400 (internal model number GK71b), on sale only in Japan, taking advantage of licensing laws there which were prohibitive of bikes over 400cc.
Second generation: 1988
The second generation of GSX-Rs, by then available in 250cc sizes too (primarily for Japan), was released in 1988, again initially on the flagship 750cc, the 1100cc version as well as the smaller siblings following a year later. The new generation GSX-R kept the same basic layout of the previous generation, but the frame was now made of large cast and formed parts, as opposed to the welded from basic rectangular tubes as in the previous generation. New “slingshot” carbs were another new feature, one that gave the model its nickname and were announced on the body with decals proclaiming this innovation.
Between major revisions all models received updates annually, sometimes quite significant, and the model name was incremented with the next letter in the alphabet beginning with F for the 1985 model. The generations are marked by major changes in the frame and/or engine.
The second generation grew in power (and weight) as suspension components were continually upgraded to deal with the increased power and traction of the improving tires of the era. By 1991 the 750cc machine was up to 458 lbs. 1991 was the first year where the dual round headlights were replaced with a more aerodynamic shape.
Third generation: 1992
In 1992 the GSX-R 750 was given the model designation GSX-R 750WN – the “W” signifying the first water-cooled engine. The innovative air-oil design of 1985 was simply no longer able to provide enough cooling for the power the engine was putting out, now a claimed 118 hp. The weight of the previous year, 458 lbs, was maintained while adding the water cooling. Also to be noted this was the last year of the “Power Jet” which came stock on the carburetors since 1989. These were noticeable by the short fuel line to the left of the carburetor, running the length from the fuel bowl to the top of the bell housing. Basic function of the power jet was the smooth out fuel delivery from 9.5k- 10k rpm all the way to the rev limiter.However, these jets were blanked out on the US models but were fully functional for Canadian buyers and other countries. The water cooled bikes would not be available to the US until 1993.
Fourth generation: 1994
A comprehensive redesign, still using the same basic frame and engine architecture but shaving an impressive 22 lbs off the bike to get it down to 436 lbs. The following year would be the last for the double downtube / angled top tube frame design that had originated on the 1985 GSX-R.
Fifth generation: 1996
The old frame design, a unique signature of the GSX-R was dated. By 1996 all of the manufacturers were using aluminum frames, and most of them were stiffer and lighter than the Suzuki frame, and featured large beams running in a straight line from the steerer tube to the swingarm pivot. The 1996 followed this principle, and along with the new frame a completely revised engine was used. As a result of this comprehensive redesign the GSX-R began its return to the front of the production racer pack, finally beginning to achieve the AMA Superbike domination it had been designed for a decade previously. The new architecture allowed the GSX-R to win an impressive 10 of 11 consecutive AMA Superbike championships beginning in 1999.
The 1996 GSX-R was a return to the original formula, with an emphasis on light weight, not just raw power. Weight was back down to an impressive 394 lbs.
Sixth generation: 2000
The year 2000 again saw a total redesign of the engine, now with dual throttle valve electronic fuel injection. A new frame was also introduced in this model that was lighter, and had a longer swingarm than the previous model. Performance was improved, and the 2000 model became one of the most appreciated of all GSX-Rs. More than a decade later, in 2011, Cycle World magazine would describe it as “one of the greatest sportbikes of all time”. Suzuki marketed the bike as “the most advanced GSX-R ever”.
After a several year break a new big-bore GSX-R was offered. In place of the unique 1100cc displacement of the old model a more standard displacement of 1000cc was produced. (This aligned better with some racing series.)
The new 1000 was built with the “modern style” architecture and it resulted in an even larger weight loss for the litre-bike: from 487 lbs to 374 lbs.[
Suzuki has released a up spec model GSX-R1000R; this R model comes with a Motion Track Brake System, Bi-directional quick shifter and launch control. Also on the R model, as reported by Sport Rider, are the same Showa Balance Free Front (BFF) fork and Balance Free Rear Cushion (BFRC Lite) shock that come standard on the 2016 Kawasaki ZX-10R.