This manual covers the Yamaha 4SD Outboards, a line of 4-stroke, in-line outboard motors designed for marine propulsion. Engineered for reliability and performance, these engines represent a robust solution for boat owners seeking dependable power on the water. Their internal combustion engine design ensures efficient operation, making them a trusted choice for various marine applications. The purpose of this English-language digital manual is to provide comprehensive service, repair, and maintenance information for the Yamaha 4SD Outboards. It includes detailed, step-by-step procedures for disassembly, repair, assembly, and inspection, supported by exploded diagrams. This resource is invaluable for owners, mechanics, and technicians, offering a cost-effective alternative to dealer-specific information and ensuring the continued optimal performance and longevity of the outboard motor.