This manual covers Yamaha C40hp, P40, C50hp, and 50hp 2-stroke outboard motors, including 40hp (28hp) and 50hp (35hp) Jet Drive models manufactured between 1998 and 2003. These robust outboard motors are engineered for reliable performance and durability in various marine applications. This service repair manual provides comprehensive guidance for the maintenance and repair of these specific Yamaha outboard motor units. The purpose of this manual is to serve as an essential resource for owners, mechanics, and technicians. It details critical maintenance procedures, troubleshooting steps, and technical specifications necessary for the upkeep of your Yamaha outboard motor. Key areas covered include general information, periodic inspections, fuel system, power unit, lower unit, electrical system, bracket unit, and diagnostics, all supported by detailed diagrams, illustrations, and step-by-step instructions to ensure optimal performance and longevity.