This service repair manual provides comprehensive technical information for Yamaha 25J, 30D, 25X, and 30X outboard motors. These engines are engineered for reliability and performance, making them a trusted choice for various marine applications. This manual covers a wide range of model variants, ensuring detailed guidance for specific configurations. The purpose of this manual is to assist both do-it-yourself owners and experienced mechanics in the repair and maintenance of these Yamaha outboard motors. It includes detailed sections on general information, specifications, periodic inspections, fuel and electrical systems, power and lower units, and troubleshooting. With easy-to-follow, step-by-step instructions, high-resolution diagrams, and wiring schematics, this guide is an essential resource for keeping your Yamaha outboard motor in optimal working condition.