The 125 S10 is equipped with a 1-cylinder rotary valve engine inherited from a GP racing machine, which was adopted by Suzuki for the first time on a practical model, and paired with a new dual muffler system. Despite having only a single cylinder, the 125 S10 generates the same level of performance as a 2-cylinder model. This dual-exhaust/dual-muffler system breaks away from the conventional approach of adopting a single muffler on 1-cylinder models. It suppresses excess increases in back pressure and realizes ideal exhaust performance, making effective use of the high power available from the engine. It also ensures excellent acceleration, resulting in a model that combines the high-speed performance of a sporty machine with the gutsy performance at low rpms of a commercial bike.

The K125 is a highly practical model that incorporates Suzuki’s original Cylinder Crank Injection (CCI) system into the engine from the 125 S10 that debuted in 1964, eliminating the need to mix lubricating oil into the fuel. In addition to a larger fuel tank and headlight, this model also features an adjustable 3-way suspension that can be set in accordance with the weight of the load being carried and the road conditions. A steel clutch plate was also adopted for greater durability. The 125 cm³ 2-stroke 1-cylinder engine has a unique dual-exhaust/dual-muffler configuration. In combination with a rotary valve, this engine realizes high power at both low and high rpms. Top speed is an impressive 110 km/h.

The K125 combines a 125 cm³ 2-stroke 1-cylinder engine with dual mufflers to generate maximum horsepower of 10.5 PS. This is a highly practical model with several new safety-oriented features such as position lights built into the headlight and side reflectors on both sides at the front and rear. The engine is paired with a rotary 4-speed automatic transmission. This model also features a large carrier capable of carrying large items with ease and a user-friendly starter.

Equipped with a double-muffler type 125 cm³ 2-stroke air-cooled 1-cylinder engine with proven and impressive durability, the K125 is a commercial bike with ample performance for a wide range of applications. A full transistor type ignition system was adopted during a minor change to realize steady ignition. The fuel tank was also redesigned, raising its capacity to 13 liters and extending the riding range.