Yamaha Four Stroke 425HP Outboard Engine

Yamaha Four Stroke 425HP Outboard Engine

Yamaha has built an enviable reputation for building highly reliable, technology driven, big horsepower engines. We have now taken this to the extreme with the release of the all-new V8 425 XTO (Extreme offshore) outboard.

This beast of an engine has been designed from the ground up to deliver maximum power and thrust. Powered by a big bore, 5.6 litre, naturally aspirated engine, the XTO Offshore opens up a whole new class of large outboard driven boats, delivering a more reliable, fuel efficient and premium quality engine solution.

The XTO Offshore is not only our most powerful outboard, it is also our most technologically advanced, with the introduction of Yamaha’s first fully integrated power system.

This system combines a revolutionary fully integrated electric steering system, with our premium CL7 multifunction display, advanced ‘drive-by-wire’ throttle controls and Helm Master joystick docking and positioning controls - creating a truly effortless boating experience.

Other key features include an in-water gear lube change system, oversized rugged gear case and hardened gears, massive 90 Amp power-generation system and large diameter XTO OS high thrust prop.

Presented in a very stylish, compact and powerful looking package, this outboard is sure to be the envy of every boat owner.

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5559CC V8 Engine

The massive 5.6 Litre, 32 valve, direct fuel-injection, four-stroke engine delivers enough power to push large and heavy offshore boats. The self-tensioning chain immersed in an oil bath ensures quiet, maintenance free and consistent valve timing.

Integrated Electric Steering

This industry first ‘steer-by-wire’ system uses an electric motor to directly move and secure the outboard, without any hydraulics or electric pump. This delivers very fast, precise, leak free and maintenance-free steering – that uses less power and is packaged in a clean rigging set-up.

Fully Integrated Power System

The fully integrated power system creates a truly effortless boating experience. The system combines integrated electric steering, ‘drive-by-wire’ throttle controls, Yamaha’s premium CL7 multifunction display and Helm Master joystick docking and positioning controls.

High Output Alternator

This powerful three winding, three phase charging system generates up to 90 Amps of electrical power. Additionally, 55 Amps of power can be generated while idling. This high output alternator enables a stable supply of power for running a wide array of electrical devices.

Direct Fuel Injection

First four-stroke outboard to use direct fuel injection in the outboard industry. A three stage fuel pump system sprays fuel at high pressure directly into the combustion chamber, resulting in better fuel burn, more power and improved fuel efficiency.

In-Water Gear Lube Servicing

The draining and replacement of the lower unit gear lubricant can occur while the boat is docked on the water, making the servicing of larger boats easier, quicker and cheaper.

Multi-Part Cowling System

By designing the cowling in separate, easily removable parts - getting to specific sections of the outboard for servicing is now quicker and easier. This new cowling design also makes it possible to service larger boats while they are docked on the water.

Redesigned Lower Unit

The hydrodynamically designed, oversized gear case enables higher maximum speeds and greater stability when turning. The high quality marine grade stainless steel components and hardened gears have been designed to handle extreme loads and highly corrosive marine environments.

Plasma Fusion Cylinders

The plasma fusion process creates a cylinder wall surface that is 60% harder than steel, removing the need for conventional steel cylinder sleeves. This significantly reduces weight, improves fuel efficiency and increases the engine capacity, resulting in an improved power-to-weight performance.

Thrust Enhancing Exhaust Routing

Blade slippage is decreased significantly when in reverse due to the exhaust gases being ducted through a ‘relief’ bypass located above the anti-cavitation plate. This improves braking capacity and reduces vibrations through the boat.


Exclusively designed for the XTO Offshore outboard, the specially designed large surface area blades generate extreme thrust for excellent acceleration, cruising, top-end speed and reduced ventilation. Includes Yamaha’s Shift Dampening System (SDS) for quieter, smoother and ‘clunk free’ gear shifting.


Our latest and most advanced display has been developed for Yamaha's range of Digital Electronic Control (DEC) outboards. The user-friendly, seven-inch touchscreen is fully customisable and can monitor up to four outboards. Functions include GPS navigation and the ability to connect to a fish finder, sonar, radar and camera.


Yamaha’s integrated Helm Master system (optional) allows for easy joystick controlled docking and precision boat positioning to deliver an effortless boating experience. Simply twist the joystick to change the boats angle or bump the joystick in any direction to move the boat accordingly. Set precise location, direction or drift settings with ease.


Many of Yamaha's mid-range and high horsepower props come with Yamaha’s exclusive Shift Dampener System (SDS). This system absorbs forces created when an engine shifts in and out of gear, resulting in a quieter, smoother and ‘clunk free’ shifting.

Engine Type

4-Stroke, 32 Valve DOHC Direct V8

Bore x Stroke (mm)

96 x 96

Fuel Tank Capacity (l)

User Selectible

Displacement (cc)


Fuel Management




OEDA Emission Rating


Lubrication System


Alternator Output

90 Amp high Output Alternator

Gear Ratio

1.79 (25/14)

Starter System


Operation Method

Steer By Wire

Trim & Tilt Method

Power Trim & Tilt

Digital Gauges


Transom Height (mm [inch])

X: 640 [25.1] | U: 767 [30.1] | E: 894 [35.1]

Dry Weight (kg)

X: 442 | U: 453 | E: 463

Yamaha XF425


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