page_title: Suzuki GSX series
section_title: GSX Development
hierarchical_section_title: Suzuki GSX series / GSX Development
caption_attribution_description: English: GSX1100 16-Valve head (GS1100)
context_page_description: The GSX Series is Suzuki's range of sport touring motorcycles powered by four-valve per cylinder four-stroke engines. The first GSX models were introduced in 1980 and represented the next step in Suzuki's four-stroke road bike range after the two-valve GS Series.
  In North America though, the Suzuki four-valve and two-valve four-stroke road bikes were both designated as Suzuki GS motorcycles.
  The two-valve engines remained in production in parallel with the four-valve power plants, the larger two-valve four-cylinder engines gaining shaft-drive and being used to power Suzuki's more touring-orientated bikes such as the GS 850G and GS 1100G, while the GSX series represented performance orientation.
context_section_description: The two-valve GS Series was Suzuki's first real foray into four-stroke motorcycles. Although Suzuki produced 90cc and 123cc four-stroke single cylinder road bikes under the brand Colleda in the mid-1950s, up until 1976 Suzuki was primarily a builder of two-stroke motorcycles.  Suzuki's range of road going motorcycles was almost entirely two-stroke in the mid-1970s (the oddball being the Wankel Rotary powered RE-5). The sophisticated Suzuki GT series and the flagship 750cc water-cooled, posi-lube lubricated, three-cylinder two-stroke GT750 characterizing  the breed.  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.
caption: GSX1100 16-Valve head (GS1100)
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