Yamaha 40VEOS Specifications
| Engine Model: Yamaha 40VEOS |
| Engine Type: 2-stroke inline 3-cylinder gasoline outboard engine |
| Total Displacement: 42.6 cu.in (698 cc) |
| Rated Engine Power: 40 Hp (29.4 kW) at 5000 rpm |
| Fuel System: Carburetor |
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The Yamaha 40VEOS is a 40-horsepower,
three-cylinder, two-stroke outboard engine from Yamaha's 40V series,
designed for boaters seeking a lightweight and powerful motor with the
convenience of electric start and oil injection in a manual-tilt
configuration. This model is specifically configured for remote control
operation, offering sophisticated features within a portable package.
The 40VEOS is celebrated for its smooth power delivery, robust
construction, and the ease of its oil injection system, which eliminates
the need for pre-mixing fuel, making it a dependable choice for a wide
array of mid-sized boats.
The Yamaha 40VEOS is constructed around a proven and efficient
powerhead. It features a 2-stroke, in-line 3-cylinder engine
configuration. The engine displacement is precisely 698 cc (42.6 cu in),
achieved through a bore and stroke of 67.0 mm x 66.0 mm (2.64 in x 2.60
in). This powerhead produces a maximum output of 29.4 kW (40 hp) at
5,000 rpm. The engine is engineered to operate within a full throttle
operating range of 4,500 to 5,500 rpm. The compression ratio is stated
as 6:1.
The power unit of the 40VEOS is engineered for durability and efficient
combustion. The engine uses a loop charge scavenging system to optimize
the fuel-air mixture and exhaust flow. Intake is managed by a reed valve
system, known for its reliability and precise control of the air-fuel
charge entering the cylinders.
| Fuel System and Lubrication |
The 40VEOS features an advanced oil injection lubrication system, which
automatically mixes the oil and fuel in the correct proportions for the
engine's operating conditions. This system eliminates the need for
pre-mixing fuel in a separate tank. The engine is fed by three
carburetors (one per cylinder) to ensure precise fuel metering.
The recommended fuel is regular unleaded gasoline with a minimum octane
rating of 86. The engine oil must be a high-quality 2-stroke outboard
motor oil meeting NMMA-certified TC-W3 grade, and it is stored in a
dedicated engine oil tank with a capacity of 1.5 L (1.6 US qt).
The ignition system is a CDI (Capacitor Discharge Ignition)
microcomputer unit, which provides precise, automatic electronic advance
for optimal performance and starting ease across the RPM range. The
system includes the Prime Start enrichment feature for effortless cold
starts.
The specified spark plugs are NGK B7HS-10 or BR7HS-10. The charging
system incorporates an alternator output of 12V, 6A with a
rectifier/regulator to maintain battery charge for the electric start
and other electrical accessories.
The cooling system is a raw-water, pressure-driven type, drawing water
from the body of water to cool the engine. Exhaust gases are expelled
through the propeller boss for efficient underwater exhaust and noise
reduction.
| Mid Section and Lower Unit |
The lower unit is engineered for strength and efficiency. It uses a
spiral bevel gear with a reduction gear ratio of 1.85 (24/13). The gear
shift positions are the standard Forward-Neutral-Reverse (F-N-R),
engaged via a positive-action dog clutch.
The propeller shaft utilizes a spline drive system, and the propeller
direction, when viewed from the rear, is clockwise. The correct
lubricant for the lower unit is hypoid gear oil meeting API GL-4 SAE 90
specifications, with a total gear oil capacity of 0.43 L (0.45 US qt).
This outboard is equipped with a manual tilt system, allowing for
adjustment of the engine angle through five preset positions. The tilt
angle can be set at 8, 12, 16, 20, or 24 degrees.
This enables the operator to set the boat's attitude for optimal
performance and fuel efficiency under various load and water conditions.
For shallow water operation and trailering, the system provides a
maximum tilt-up angle of 66 degrees. The steering angle is 40 degrees to
both port and starboard.
To accommodate various boat types and applications, the Yamaha 40VEOS
can be fitted with a wide selection of aluminum propellers to ensure the
engine operates within its recommended full-throttle RPM range. The
available propeller options, all with three blades, encompass various
diameter and pitch combinations.
These include: 3 x 10 x 15, 3 x 10-1/4 x 14, 3 x 10-3/4 x 16, 3 x 10-3/4
x 17, 3 x 10-3/8 x 13, 3 x 10-5/8 x 12, 3 x 11-1/8 x 13, 3 x 11-1/4 x
14, 3 x 11-3/8 x 12, 3 x 11-5/8 x 11, 3 x 11-3/4 x 10, 3 x 12-1/4 x 9, 3
x 12 x 11, and 3 x 12 x 12.
The Yamaha 40VEOS is available in a short shaft configuration. The
overall length is 670 mm (26.4 in) and the overall width is 349 mm (13.7
in). The overall height is 1,192 mm (46.9 in) with a transom height of
381 mm (15.0 in). The dry weight for this model is 74.5 kg (164 lb).
Regular maintenance is essential for the longevity of the 40VEOS. A
critical pre-operation check involves verifying the oil level in the
remote engine oil tank. The gear oil in the lower unit should be checked
regularly for the presence of water or metal particles and changed
according to the manufacturer's schedule, which generally recommends an
initial change after the first 10 hours of operation and then annually
or every 100 hours.
The water pump impeller is a wear item that should be inspected and
replaced periodically, typically every 1-2 years or if there are signs
of reduced cooling water flow, to prevent overheating. The spark plugs
should be removed, inspected, cleaned, and the gap adjusted annually,
and replaced as needed. All moving parts, such as steering linkages and
tilt tube, require regular greasing with water-resistant marine grease
to prevent corrosion and ensure smooth operation.
Cylinder head bolt (1st step): 15 Nm (11 lb-ft)
Cylinder head bolt (2nd step): 28 Nm (20 lb-ft)
Engine unit bolt: 21 Nm (15 lb-ft)
Flywheel nut: 110 Nm (80 lb-ft)
Reed valve bolt: 1 Nm (0.7 lb-ft)
Spark plug: 25 Nm (18 lb-ft)
Propeller nut: 30 Nm (22 lb-ft)
Lower unit bolt: 40 Nm (29 lb-ft)
Propeller shaft housing bolt: 16 Nm (11 lb-ft)
Tiller handle mounting nut: 38 Nm (27 lb-ft)
Steering friction mounting nut: 20 Nm (14 lb-ft)
Tiller handle pivot bolt: 38 Nm (27 lb-ft)
Muffler bolt: 21 Nm (15 lb-ft)
Exhaust manifold bolt: 21 Nm (15 lb-ft)
Exhaust guide bolt: 21 Nm (15 lb-ft)
The Yamaha 40VEOS is a versatile power source ideally suited for a wide
range of mid-sized watercraft. Its 40-horsepower output, combined with
the convenience of electric start and oil injection, makes it a perfect
match for bay boats, center consoles, tiller-steer utility boats, and
aluminum fishing boats commonly used on larger inland lakes and coastal
waters.
The manual tilt system provides reliable, simple operation while
maintaining the ability to navigate in shallow water. The oil injection
system and remote control capabilities provide an elevated level of
convenience for boaters seeking a powerful, easy-to-operate outboard
without the complexity of power trim.
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