Yamaha F50H Specifications
| Engine Model: Yamaha F50H |
| Engine Type: 4-stroke inline 4-cylinder SOHC 8-valve gasoline outboard engine |
| Total Displacement: 60.8 cu.in (996 cc) |
| Rated Engine Power: 50 Hp (36.8 kW) at 5500 rpm |
| Fuel System: Electronic Fuel Injection (EFI) |
____________________________________________________________________________________
The Yamaha F50H is a 50-horsepower,
four-stroke, in-line four-cylinder outboard engine, representing a
benchmark of refinement and technology in Yamaha's mid-range lineup.
This engine family includes three distinct models - the F50HEHD, F50HED,
and F50HET - each tailored for specific steering configurations while
sharing the same advanced 996cc platform.
All models are equipped with electric starting and a hydraulic power
trim and tilt system, offering boaters a sophisticated, powerful, and
exceptionally smooth experience. The F50H series is renowned for its
quiet operation, outstanding fuel efficiency, and the seamless response
of its Electronic Fuel Injection system, making it a versatile and
dependable choice for a wide array of mid-sized boats.
The Yamaha F50H is constructed around a refined and efficient powerhead.
It features a 4-stroke, SOHC, in-line 4-cylinder, 8-valve engine
configuration. The engine displacement is precisely 996 cc (60.8 cu in),
achieved through a bore and stroke of 65.0 mm x 75.0 mm (2.56 in x 2.95
in).
This powerhead produces a maximum prop shaft output of 36.8 kW (50 hp)
at 5,500 rpm. The engine is engineered to operate within a full throttle
operating range of 5,000 to 6,000 rpm, with a specified engine idle
speed of 700-800 rpm. The compression ratio is stated as 9.5:1. Fuel
consumption at 5,500 rpm is 17.6 L/h.
The power unit of the F50H is engineered for durability, efficiency, and
smooth power delivery. The engine's design incorporates a long intake
manifold and increased piston stroke, contributing to a broad, flat
torque curve and impressive acceleration. Its smooth torque
characteristic is attributed to the long intake manifold design and
increased piston stroke, which differs from conventional designs.
The valve train requires periodic adjustment, with specified valve
clearances of 0.15-0.25 mm (0.006-0.010 in) for the intake valves and
0.25-0.35 mm (0.010-0.014 in) for the exhaust valves when the engine is
cold. The ignition timing ranges from ATDC 10.0 to BTDC 25.0 degrees
depending on operating conditions.
The F50H features Yamaha's advanced Electronic Fuel Injection (EFI)
system, which precisely meters fuel for optimal combustion under all
conditions. Managed by a microcomputer receiving data from six different
engine sensors, this system ensures cleaner performance, impressive fuel
economy, and seamless throttle response.
The EFI system features reduced vaporization for enhanced performance.
The recommended fuel is regular unleaded gasoline with a minimum octane
rating of 86. The engine is supplied with fuel from a separate tank with
a capacity of 25.0 L (6.6 US gal).
The lubrication system is a wet sump type, meaning the engine oil is
stored in a sump within the engine. The recommended engine oil is
high-quality 4-stroke outboard motor oil, such as Yamalube, in SAE
10W-30 or 10W-40 viscosities, meeting API SE, SF, SG, SH, SJ, or SL
service classifications. The engine oil capacity with oil filter
replacement is 2.1 L (2.2 US qt), while the capacity during a change
without filter replacement is 1.9 L (2.0 US qt).
The cooling system is raw-water, thermostatically controlled, drawing
water from the body of water to cool the engine. A freshwater flushing
device is integrated for easy maintenance. Exhaust gases are expelled
through the propeller boss for efficient underwater exhaust and noise
reduction.
The ignition system is a TCI (Transistor Controlled Ignition) unit,
providing precise spark timing for reliable starting and efficient power
across the RPM range. The system includes the Prime Start feature for
effortless cold starts, similar to starting a car.
The specified spark plugs are NGK DPR6EB-9, with a required gap of
0.8-0.9 mm (0.031-0.035 in). The charging system incorporates a
high-output alternator of 12V - 16A with a built-in rectifier/regulator,
providing 9A battery charging capacity to maintain battery charge for
the electric start and other electrical accessories.
| 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 1.85:1 (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 gear oil capacity of 0.43 L (0.45 US qt).
This outboard is equipped with a hydraulic power trim and tilt system,
allowing for effortless adjustment of the engine angle with the touch of
a button. The trim angle can be adjusted through five positions on the
hydro unit.
For shallow water operation, the system provides a standard shallow
water drive feature, allowing the engine to be operated at a tilted
angle for safe navigation. The steering angle is 40 degrees to both port
and starboard.
The Yamaha F50H is compatible with a range of aluminum and stainless
steel propellers to match various boat types and applications.
Authorized Yamaha dealers can recommend the correct propeller based on
boat hull, load, and intended use to ensure the engine operates within
its recommended full-throttle RPM range of 5,000-6,000 rpm. The
propeller drive system utilizes a spline connection.
F50HEHD (Tiller Handle Model): Overall length is 1,380 mm (54.3 in).
Overall width is 386 mm (15.2 in). Overall height (long shaft) is 1,435
mm (56.5 in) with a transom height of 527 mm (20.7 in). The dry weight
for this model is 111 kg (245 lb).
F50HED (Remote Control Model): Overall length is 698 mm (27.5 in).
Overall width is 386 mm (15.2 in). Overall height (long shaft) is 1,435
mm (56.5 in) with a transom height of 527 mm (20.7 in). The dry weight
for this model is 112 kg (247 lb).
F50HET (Remote Control Model): Overall length is 698 mm (27.5 in).
Overall width is 386 mm (15.2 in). Overall height (long shaft) is 1,435
mm (56.5 in) with a transom height of 527 mm (20.7 in). The dry weight
for this model is 113-114 kg (249-251 lb).
Regular maintenance is essential for the longevity of the F50H. The
engine oil and oil filter should be changed according to the
manufacturer's schedule, with the oil filter change torque specified at
18 Nm (13.5 lb-ft). The gear oil in the lower unit should be checked
regularly for the presence of water or metal particles and changed
annually or every 100 hours.
The water pump impeller is a wear item that should be inspected and
replaced periodically, 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. Valve clearance inspection and adjustment should be performed
at recommended intervals.
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. Modern warning systems monitor oil
pressure, temperature, and other key parameters, activating audible and
visual alerts if malfunctions occur. The engine is compatible with
Yamaha's Digital Network Gauges for precise control and monitoring. An
optional Y-COP engine immobiliser system is available for enhanced
security.
Spark plug: 17 Nm (12.5 lb-ft)
Propeller nut: 34 Nm (25 lb-ft)
Oil drain plug: 27 Nm (20 lb-ft)
Oil filter: 18 Nm (13.5 lb-ft)
The Yamaha F50H is a versatile power source ideally suited for a wide
range of mid-sized watercraft up to approximately 5 meters in length.
Its 50-horsepower output, combined with the convenience of electric
start, EFI, and power trim and tilt, makes it a perfect match for
aluminum fishing boats, center consoles, bay boats, and utility boats
commonly used on inland lakes and coastal waters.
The tiller-handle F50HEHD model is particularly popular for tiller-steer
fishing boats, while the remote-control F50HED and F50HET models are
ideal for console-steer vessels. The four-stroke technology provides
exceptionally clean and quiet operation, making it suitable for various
recreational applications including fishing, touring, and family
outings.
____________________________________________________________________________________
| Outboard Engines Technical Specifications |
| Small Engines Technical Specifications |
| Car Engines Technical Specifications |
| Industrial Engines Technical Specifications |
