This document provides comprehensive technical information for the Yamaha F300, LF300, F350, and LF350 marine outboard motors. These four-stroke gasoline engines are engineered for reliable marine propulsion, representing Yamaha's commitment to quality and performance in demanding aquatic environments. Their robust design and advanced features ensure efficient operation for a wide range of boating applications. This Factory Service Repair Manual is designed to be an essential resource for owners, technicians, and mechanics. It covers general information, detailed specifications, technical features, rigging procedures, and troubleshooting guidance. The manual includes in-depth coverage of the electrical system, fuel system, power unit, lower unit, and bracket unit, along with a complete maintenance schedule and step-by-step maintenance procedures. This extensive documentation ensures proper upkeep and repair, maximizing the longevity and performance of your Yamaha outboard motor.