This Service Repair Manual covers the Yamaha 4MHU and 5MHU models. These outboard motors are designed with a 4-stroke, single-cylinder engine configuration, delivering reliable performance with either 4 HP or 5 HP output. They feature water cooling and a CDI ignition system, ensuring efficient operation. The tiller handle provides straightforward steering and manual tilt functionality, making them suitable for a variety of small watercraft applications where dependable power is essential. This manual provides comprehensive guidance for the maintenance and repair of your Yamaha outboard motor. It details essential procedures, including recommended maintenance schedules and specifications for fluids and fuel. Technical information on engine and transmission components, along with performance system details, is included to assist with diagnostics and repairs. By following the instructions within this manual, owners and technicians can ensure the longevity and optimal performance of their Yamaha 4MHU or 5MHU outboard motor.