This Technical Workshop Manual provides comprehensive coverage for the 25HP Marathon and 25HP SeaPro outboard motors, manufactured between 1998 and 2003. These 2-stroke, water-cooled gasoline engines are designed for reliable performance, delivering 25 horsepower and featuring a CDI ignition system. The manual is presented in English and offers detailed information essential for understanding and maintaining these robust marine propulsion units, emphasizing their engineering quality and operational efficiency for various watercraft applications. This manual serves as an indispensable resource for owners, mechanics, and technicians. It includes detailed service and repair procedures, diagnostic guidance, and troubleshooting steps to ensure optimal performance and longevity of your outboard. With clear, illustrated instructions, zoomable diagrams, and exploded views of components, this manual facilitates everything from routine maintenance, such as lubrication with specified 2-stroke outboard oil, to complete engine restoration and rebuilds. It is compatible with multiple operating systems, ensuring accessibility for a wide range of users.