This manual covers the GSX-R400, a renowned sportbike produced from 1984 to 1987, including models with chassis codes GK71B and GK73A. The legacy in performance motorcycles is evident in the GSX-R400, which offered a potent blend of handling and speed within its displacement class, often earning accolades for its engineering and dynamic capabilities. This model represents a significant entry in the sportbike lineage, providing an accessible yet thrilling riding experience. This comprehensive workshop service and repair manual provides in-depth information for owners and technicians. It details maintenance schedules, engine rebuild procedures, fuel system servicing, cooling system management, chassis and brake system repairs, and electrical system diagnostics. With detailed illustrations, torque specifications, and troubleshooting guidance for common issues, this manual is an indispensable resource for maintaining, repairing, and ensuring the optimal performance of your GSX-R400.