The Selped 80K10 was developed with the aim of realizing comparable performance to models in the 125 cm³ class, while taking full advantage of the economy, rideability, and easy handling of a moped. At only 70 kg, this was the lightest model in its class at the time. The compactly designed 80 cm³ 2-stroke air-cooled 1-cylinder engine weighs only 17.5 kg, equivalent to that of a 50 cm³ model. Despite its low weight, this engine is capable of generating maximum horsepower of 6.5 PS as well as smooth and superb acceleration from low- to high- rpm ranges. The engine is paired with a rotary 4-speed transmission. The chassis features a plastic front fender, headlight cover, battery box, and the like, which also help to reduce weight to the equivalent of a 50 cm³ model.

The K90 pairs a pressed backbone frame with the proven high-performance rotary disc valve engine from the A90 that generates maximum horsepower of 8.4 PS and a top speed of 100 km/h. It also features the Cylinder Crank Injection (CCI) lubrication system, which enables continuous riding at high speeds. Design accents include the same fuel tank as the A90.

The K90 is a commercial model with an agile design that combines a new V-shaped frame with a rear fender separated from the frame. A good-looking fuel tank, oil tank, and other parts were adopted to match the new frame. The semi-upright handlebars feature a larger pipe diameter, and are positioned higher and wider than the previous model, realizing an even more comfortable ride. This model is also equipped with 18-inch wheels, one size larger than the K50, which help to improve both riding performance and comfort. The rotary valve 90 cm³ 2-stroke air-cooled 1-cylinder engine generates maximum horsepower of 8.4 PS.

The styling of the K90 was completely updated by changing the shape of the fuel tank and frame cover. The 90 cm³ 2-stroke 1-cylinder reed valve engine realizes its full potential in the low- and mid-rpm ranges, generating maximum horsepower of 7.5 PS and maximum torque of 9.3 N·m. The K90 is an easy-handling model with a dry weight of only 80 kg that remained on sale until it was withdrawn from the market in 2000.