This manual covers the Yamaha 90C outboard motor, a robust 4-stroke, water-cooled engine designed for reliable performance on the water. Featuring a 1596 cc displacement and producing 90 horsepower from its 3-cylinder configuration, this motor is engineered for efficiency and power. It offers a Forward-Neutral-Reverse gear selection with a 2.00:1 gear reduction ratio and is commonly equipped with a power trim and tilt system for optimal control. The engine utilizes CDI ignition and an electric start system, with an alternator output of 16A at 1000 RPM. Fuel is delivered via multi-port Electronic Fuel Injection (EFI) on later models or carburetion on earlier versions, running on 87 octane unleaded gasoline. This comprehensive Service Repair Manual / Workshop Manual in English provides essential information for the maintenance and repair of your Yamaha 90C outboard motor. It details critical procedures, technical specifications, and troubleshooting guidance necessary for optimal performance and longevity. Key areas covered include lubrication requirements, such as specific oil types and capacities, along with recommended intervals for gear lube changes. While specific intervals for spark plug and fuel filter replacement are to be referred to within the manual, this document serves as an indispensable resource for owners, mechanics, and technicians to ensure the continued reliability and proper functioning of this powerful outboard motor.