Description

Read Before You Buy 2008 Yamaha 40HP Engine

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2008 Yamaha 40HP 4-Stroke EFI Outboard Motor For Sale

The 2008 Yamaha 40HP is a practical mid-range outboard designed for boat owners who need dependable propulsion, smooth four-stroke performance, and economical operation without moving into a heavier high-horsepower engine class. Powered by a 747cc three-cylinder powerhead, this Yamaha combines electronic fuel injection, SOHC valve technology, natural aspiration, and mechanical controls in a compact marine package.

This particular engine is listed as a 2008 used Yamaha 40HP with approximately 222 operating hours, a 20-inch shaft, and a dry weight of approximately 214 lbs / 97 kg. Its combination of manageable weight and 40HP output makes it suitable for aluminum fishing boats, skiffs, jon boats, inflatables, pontoons, utility vessels, and other appropriately rated recreational boats.

Product Overview

The Yamaha 40HP provides a useful balance between compact dimensions and practical marine performance. Its three-cylinder configuration is designed to deliver smooth power while providing enough torque for small-to-mid-size boats carrying passengers, fishing equipment, fuel, and other onboard gear.

The engine uses a 747cc four-stroke powerhead with SOHC valve technology and electronic fuel injection. EFI provides controlled fuel delivery for consistent starting, throttle response, and operation across different engine speeds and loads.

With a 20-inch shaft, mechanical controls, and a listed dry weight of approximately 214 pounds, this engine can be a practical choice for both replacement and repower applications.

Key Features

• 40 HP output
• 2008 model year
• Used condition
• Approximately 222 operating hours
• 747cc displacement
• 3-cylinder configuration
• 4-stroke engine
• SOHC valve design
• Electronic Fuel Injection
• Naturally aspirated
• 20-inch shaft
• Approximately 214 lbs / 97 kg dry weight
• 16-amp alternator
• Mechanical controls
• Smooth mid-range torque
• Wet-sump lubrication
• Corrosion-resistant marine construction
• Suitable for freshwater and saltwater applications
• Suitable for fishing, recreational, and utility boats

Technical Specifications

Specification	Details
Brand	Yamaha
Model	2008 Yamaha 40HP
SKU	Y435689
Category	Outboard Engine
Condition	Used
Model Year	2008
Horsepower	40 HP
Fuel Type	Gasoline
Displacement	0.75 L / 747cc
Number of Cylinders	3
Engine Configuration	Inline 3-Cylinder
Engine Cycle	4-Stroke
Valve Configuration	SOHC
Fuel System	Electronic Fuel Injection
Aspiration	Naturally Aspirated
Shaft Length	20 inches
Weight	214 lbs
Dry Weight	97 kg / 214 lbs
Operating Hours	Approximately 222
Rated Output	29.4 kW / 40 HP
Rated Speed	6,000 RPM
Bore x Stroke	65 mm × 75 mm
Alternator	16 Amp
Controls	Mechanical

40 HP Performance

The Yamaha 40HP produces 40 horsepower, making it a versatile choice for smaller boats that require more power than portable outboards but do not need a larger 50–90HP engine.

The three-cylinder configuration provides smooth power delivery while the 747cc displacement provides useful torque for acceleration and cruising.

The listed rated speed is 6,000 RPM, with the engine generally operating within approximately 5,000–6,000 RPM at wide-open throttle, depending on the exact configuration and propeller setup.

Actual performance depends on:

• Boat weight
• Hull design
• Propeller selection
• Engine mounting height
• Passenger load
• Fuel and equipment load
• Water conditions
• Boat trim

A lightweight aluminum fishing boat can achieve very different performance from a heavier pontoon using the same engine.

747cc Three-Cylinder Engine

The Yamaha 40HP uses a 747cc three-cylinder powerhead.

The three-cylinder configuration offers a practical balance between smoothness, power, weight, and compact dimensions.

The 747cc displacement gives the engine enough capacity to provide useful mid-range torque while remaining suitable for boats where excessive engine weight is undesirable.

This makes the 40HP particularly practical for fishing and recreational boats that regularly operate under varying loads.

Four-Stroke SOHC Design

The Yamaha 40HP uses a four-stroke combustion cycle and a single overhead camshaft (SOHC) configuration.

The four-stroke design is well suited to owners who want smooth and predictable operation during cruising, fishing, trolling, and general utility use.

The SOHC arrangement provides straightforward valve control while supporting efficient airflow through the three-cylinder powerhead.

Electronic Fuel Injection

The engine uses Electronic Fuel Injection (EFI) to regulate fuel delivery.

EFI can provide several advantages over older carbureted systems, including:

• Easier starting
• Smoother idle
• More consistent throttle response
• Precise fuel metering
• Better fuel control
• Stable operation across different loads
• Efficient combustion

For a used outboard intended for regular boating, EFI provides convenient operation while reducing dependence on manual fuel-system adjustments.

Naturally Aspirated Operation

The Yamaha 40HP is naturally aspirated.

It does not use a turbocharger or supercharger. Instead, its 40HP output is produced through the 747cc displacement, three-cylinder configuration, SOHC valve system, and electronic fuel injection.

The naturally aspirated design provides predictable power delivery and is well suited to general-purpose marine applications.

20-Inch Shaft

This particular Yamaha 40HP is specified with a 20-inch shaft.

A 20-inch shaft is commonly used with boats having a long-shaft transom and can be suitable for many fishing boats, aluminum boats, inflatables, and recreational vessels.

Correct shaft length is important for maintaining proper:

• Propeller depth
• Cooling-water pickup
• Engine mounting
• Boat handling
• Acceleration
• Propeller efficiency

Before installation, verify the boat’s transom height and manufacturer’s recommended shaft length.

214-Pound Dry Weight

The engine is listed at approximately 214 lbs / 97 kg dry weight.

This places the Yamaha 40HP in a manageable weight class for many small and mid-size boats.

The engine weight should nevertheless be considered when performing a repower. Replacing a significantly lighter engine with the Yamaha 40HP can alter:

• Stern height
• Static trim
• Boat balance
• Planing behavior
• Handling

The boat’s transom should always be rated for the engine’s horsepower and weight.

Mechanical Controls

The Yamaha 40HP is listed with mechanical controls.

This makes it important to verify compatibility with the boat’s existing throttle, shift, steering, and rigging systems during a repower.

Before installation, check:

• Throttle cable
• Shift cable
• Steering system
• Control box
• Engine harness
• Battery connections
• Instrumentation
• Mounting hardware

The exact control arrangement should be confirmed for the individual used engine.

16-Amp Alternator

The detailed specification lists a 16-amp alternator.

The charging system can provide electrical power for the starting battery and onboard equipment while the engine is running.

For boats equipped with multiple electronics, the electrical requirements of the vessel should be evaluated to ensure that the battery and charging system are appropriately sized.

Wet-Sump Lubrication

The engine uses a wet-sump lubrication system.

Regular engine-oil maintenance is important for protecting the internal components and maintaining proper lubrication.

For a used engine, it is useful to establish:

• When the oil was last changed
• When the filter was replaced
• Whether the engine has been serviced regularly
• Whether the engine has experienced overheating or oil-pressure warnings

The correct oil type and service interval should follow the applicable Yamaha maintenance requirements.

Boat Applications

The Yamaha 40HP can be suitable for a wide range of appropriately rated boats.

Potential applications include:

• Aluminum fishing boats
• Small center consoles
• Jon boats
• Fishing skiffs
• Inflatable boats
• Pontoons
• Utility boats
• Small recreational boats
• Tender boats
• Light commercial vessels

The appropriate boat size depends on the hull design, vessel weight, passenger capacity, and manufacturer horsepower rating.

Fishing Applications

The 40HP class is particularly useful for fishing boats that need a balance of maneuverability and useful cruising power.

The Yamaha 40HP can be used for:

• Freshwater fishing
• River fishing
• Lake boating
• Coastal fishing
• Trolling
• General cruising
• Utility transportation

The engine’s three-cylinder design provides smooth operation for long periods on the water.

Used Yamaha 40HP — Approximately 222 Hours

This particular engine is listed as a 2008 used Yamaha 40HP with approximately 222 hours.

Operating hours provide useful information, but they should not be used as the only indicator of a used engine’s condition.

Important inspection areas include:

• Compression
• Starting performance
• Idle quality
• Cooling-water flow
• Diagnostic information
• Gearcase condition
• Gear oil
• Propeller
• Water pump
• Fuel system
• Spark plugs
• Alternator
• Battery connections
• Corrosion
• Service history

An engine with documented service history can provide considerably more useful information than an engine evaluated only by its hour count.

Saltwater Operation

The Yamaha 40HP can be used in saltwater environments, but proper maintenance is important.

Saltwater can contribute to corrosion around:

• Engine mounting brackets
• Fasteners
• Electrical connections
• Cooling passages
• Steering components
• Lower unit
• Sacrificial anodes

After saltwater operation, freshwater flushing can help remove salt deposits from the cooling system.

Regular inspection and replacement of sacrificial anodes is also important for coastal use.

Fuel Requirements

The supplied specifications indicate the Yamaha 40HP should use unleaded gasoline with a minimum octane rating of approximately 87 and no more than approximately 10% ethanol.

Fuel quality is especially important on an EFI engine.

Good fuel practices include:

• Using clean gasoline
• Avoiding stale fuel
• Checking for water contamination
• Maintaining fuel filtration
• Inspecting fuel lines
• Properly storing the boat and fuel

The exact fuel requirements should be confirmed for the engine’s individual configuration.

Maintenance

Regular maintenance is essential for preserving the performance of a used Yamaha 40HP.

Common service areas include:

• Engine oil
• Oil filter
• Lower-unit gear oil
• Spark plugs
• Fuel filter
• Water pump and impeller
• Cooling system
• Sacrificial anodes
• Propeller
• Battery
• Electrical connections
• Steering system
• Throttle and shift controls

The supplied maintenance information references oil and filter service at approximately 100 hours or annually, following the applicable initial break-in requirements.

For this engine’s approximately 222 hours, maintenance records should be reviewed to determine which services have already been completed.

Propeller Selection

Propeller selection has a significant effect on the performance of a 40HP outboard.

The correct propeller depends on:

• Boat weight
• Hull design
• Boat length
• Passenger load
• Engine mounting height
• Intended use
• Desired acceleration
• Cruising speed

The goal is to allow the engine to reach its appropriate full-throttle RPM range while providing good acceleration and efficient cruising.

A propeller suited to a lightweight fishing skiff may not be suitable for a heavier pontoon or utility boat.

Repower Applications

The Yamaha 40HP can be a practical replacement engine for an appropriately rated boat.

Before repowering, verify:

• Maximum boat horsepower
• Transom height
• Shaft length
• Engine weight
• Steering system
• Throttle and shift controls
• Electrical connections
• Fuel system
• Propeller
• Engine mounting arrangement

The 214-pound dry weight should be compared with the engine being replaced to ensure that the boat’s balance and transom loading remain appropriate.

Why Choose to Buy 2008 Yamaha 40HP Engine?

The Yamaha 40HP offers a useful combination of compact size, three-cylinder smoothness, EFI fuel delivery, and four-stroke operation.

Key advantages include:

• 40 HP output
• 747cc displacement
• Three-cylinder configuration
• Four-stroke operation
• SOHC valve technology
• Electronic fuel injection
• Naturally aspirated design
• 20-inch shaft
• Approximately 214-pound dry weight
• 16-amp alternator
• Mechanical controls
• Wet-sump lubrication
• Suitable for fishing and recreational boating
• Practical repower option for appropriately rated boats

Frequently Asked Questions

How much horsepower does the Yamaha 40HP produce?

The engine produces 40 horsepower, equivalent to approximately 29.4 kW.

What year is this Yamaha 40HP?

This particular engine is listed as a 2008 model.

How many hours does it have?

The engine is listed with approximately 222 operating hours.

What is the displacement?

The engine has a listed displacement of 0.75 liters / 747cc.

How many cylinders does it have?

It uses a three-cylinder configuration.

Is the Yamaha 40HP a four-stroke?

Yes. It is a four-stroke outboard engine.

Does it use electronic fuel injection?

Yes. The detailed specifications identify the engine as using electronic fuel injection.

What is the shaft length?

This particular engine is listed with a 20-inch shaft.

How much does the Yamaha 40HP weigh?

The listed dry weight is approximately 214 lbs / 97 kg.

Does the Yamaha 40HP have an alternator?

Yes. The detailed specification lists a 16-amp alternator.

Can it be used in saltwater?

Yes. It can be used in saltwater, but freshwater flushing, corrosion protection, and regular inspection are important.

What boats can use a Yamaha 40HP?

Depending on the manufacturer’s rating, it can be suitable for aluminum fishing boats, skiffs, jon boats, inflatables, pontoons, utility boats, and other small-to-mid-size vessels.

What fuel should be used?

The supplied specifications indicate unleaded gasoline with a minimum octane rating of approximately 87 and no more than about 10% ethanol.

What is the recommended operating RPM?

The engine is listed at 6,000 RPM rated speed, with a typical operating range of approximately 5,000–6,000 RPM at wide-open throttle.

Is 222 hours a lot for a 2008 Yamaha 40HP?

The reported 222 hours should be considered together with the engine’s age, service history, storage conditions, and mechanical condition. Hours alone do not establish the condition of a used marine engine.

Specification Note

The supplied product information contains a small discrepancy regarding the alternator. The detailed specification lists a 16-amp alternator, while one FAQ references a 17-amp alternator.

For the product listing, the detailed specification of 16 amps should be used unless the exact engine identification or service documentation confirms otherwise.

Final Thoughts

The 2008 Yamaha 40HP 4-Stroke EFI Outboard is a practical choice for boat owners looking for reliable mid-range propulsion in a manageable package.

With 40 HP, 747cc displacement, three-cylinder four-stroke construction, SOHC technology, EFI, a 20-inch shaft, approximately 214 lbs of dry weight, mechanical controls, and around 222 operating hours, it is well suited to fishing boats, aluminum boats, skiffs, jon boats, inflatables, pontoons, and utility vessels.

For a used engine of this age, buyers should place particular emphasis on service history, compression, cooling-system performance, lower-unit condition, corrosion, fuel-system condition, and overall mechanical inspection before installation or repowering.