This manual covers the Suzuki GS250 Twin, GSX250, GS400 Twin, and GS450 Twin models manufactured between 1979 and 1985. These air-cooled, 4-stroke parallel-twin motorcycles, featuring either DOHC (GSX) or SOHC (GS) engines, were known for their reliable performance and solid engineering, establishing Suzuki's reputation in the street motorcycle market during the 1980s. The GS series offered a balanced blend of power and handling suitable for everyday riding and touring. This comprehensive Factory Service Repair Workshop Manual provides detailed, step-by-step instructions for the full service and repair of these Suzuki models. It covers all major systems, including engine overhaul, fuel and electrical systems, transmission, brakes, and suspension, along with maintenance procedures, troubleshooting guides, and technical specifications. With detailed photos, diagrams, and exploded views, this English-language manual is an essential resource for owners and technicians aiming to maintain and repair their Suzuki GS series motorcycles.