The TU250 is a standard motorcycle made by Suzuki. It is called the ST250 in the Japanese market, and is a popular platform for customization.
TU250x is known as the ST250 E Type in the Japanese market. TU250 is known as the Volty in the Japanese market. The early stage 1995-2004 TU series is actually the Volty series. Volty shares a fairly similar design to ST series but of course there is some difference, such as the shape of the seat and the oil tank. The frame and engine are nearly identical to those used in the Volty and Grasstracker. The cleaner-burning TU250X, however, adds fuel injection and an exhaust oxygen sensor.
TU250 series was discontinued in 2005 and replaced by TU250x in the export market. The TU250G or TU250GB is the Japanese domestic model of Grasstracker Bigboy. Another Japanese variant is the VanVan, with a similar body the other models, and not exported.