This manual covers the GS and GSX series motorcycles produced between 1979 and 1985, including models with 250cc, 400cc, and 450cc engine variants. These motorcycles are known for their robust engineering, offering a blend of performance and reliability that made them popular in their era. The GS series laid the groundwork for larger displacement offerings, evolving into the sportier GSX line, which often featured advancements like DOHC valve trains and responsive handling. With a focus on mechanical integrity and rider feedback, these models represent a significant chapter in motorcycle heritage. This comprehensive service repair workshop manual provides detailed, vehicle-specific information for owners and technicians. It covers a wide range of essential topics, including general information, routine maintenance procedures, detailed specifications, periodic checks, lubrication, cooling systems, transmissions, drive chains, fuel systems, steering, suspension, bodywork, intake and exhaust, and the electrical system. The manual offers step-by-step instructions for engine overhaul, advanced troubleshooting, and component repair, mirroring the procedures used by authorized dealer service departments. It is designed to facilitate effective maintenance and repair, ensuring the longevity and optimal performance of your GS or GSX motorcycle.