This manual covers the Yamaha 60C, 70C, and 90C outboard motors manufactured in 2004. These water-cooled, carbureted engines feature a CDI ignition system and may include an oil injection system on specific models. Engineered for reliability and performance, these outboard motors are designed to provide dependable power for a variety of marine applications. This document provides comprehensive information to ensure optimal operation and longevity of your Yamaha outboard motor. The purpose of this Service & Repair Manual is to provide detailed guidance for the maintenance, servicing, and repair of the specified Yamaha outboard motor models. It includes essential information such as maintenance schedules, lubrication procedures, fluid capacities, and component-specific service instructions, including carburetor adjustment, spark plug replacement, fuel filter changes, and water pump impeller replacement. A troubleshooting guide with a trouble analysis chart is also provided to assist in diagnosing and resolving potential issues. This manual is an indispensable resource for owners, technicians, and mechanics seeking to maintain their engines.