Suzuki has defined sportbike performance for more than 30 years. It started with the legendary GSX-R line, with more than a million sold worldwide. And the dedicated Suzuki engineers behind the GSX-R line take their responsibilities very seriously: Every GSX-R must be very light and best performing in its class, in an unbeatable package. Now Suzuki engineers have applied their expertise and design philosophy to an exciting new street sport 125cm3-class motorcycle, based on the revolutionary GSX-R125. Meet the new lightweight king of the streets, the Suzuki GSX-S125.
There is a science to building high-performance engines, and the GSX-S125’s DOHC engine could be used in a university textbook as an example of how to make a lot of performance out of a very efficient and compact powerplant. The objective is combustion efficiency, optimal balance of the sporty engine character and fuel economy. There is a connection between the GSX-S125 and the race-proven four-cylinder GSX-R600 sold around the world, because the GSX-S125’s single cylinder is almost one-quarter of a GSX-R600.
Although Suzuki engineers experimented with different bore and stroke figures to find the most efficient combination for the GSX-S125, the two engines both use an over-square design, with a larger bore and a shorter stroke, and have a similar bore x stroke ratio, 1.576:1 for the GSX-R600 and 1.505:1 for the GSX-S125. The GSX-S125 engine displaces an actual 125cm3 from a 62mm cylinder bore and a 41.2mm piston stroke. The larger bore makes room for two 24mm intake valves and two 21mm exhaust valves, set upright at narrow angles to improve the shape of the combustion chamber, increasing the compression ratio, performance and fuel economy. The cylinder bore is plated with Suzuki’s own race-proven nickel-phosphorus-silicon-carbide bore coating known as SCEM (Suzuki Composite Electrochemical Material). An aluminum cylinder plated with SCEM weighs much less than an aluminum cylinder fitted with a conventional, pressed-in cast-iron liner, while also reducing friction and improving durability, ring seal, heat transfer and the engine’s ability to maintain consistent high-power output.
An effective liquid-cooling system with a large radiator helps keep the engine at the optimum temperature, producing consistent performance and maximizing fuel efficiency and mileage. The engine makes its high horsepower and reaches its generous torque, delivering strong, effective power across a broad rpm range. And the GSX-S125 comes with a smooth-shifting 6-speed transmission and an electric starter.
