Suzuki DF4A Specifications
| Engine Model: Suzuki DF4A |
| Engine Type: 4-stroke 1-cylinder OHV gasoline outboard engine |
| Total Displacement: 8.4 cu.in (138 cc) |
| Rated Engine Power: 3.9 Hp (2.9 kW) at 5000 rpm |
| Fuel System: Carburetor |
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The Suzuki DF4A is a technologically advanced
portable outboard that redefines expectations for small four-stroke
engines. It is engineered to deliver surprising low- and mid-range
torque for quick acceleration while maintaining the fuel efficiency and
quiet operation characteristic of four-stroke design.
Owners benefit from innovative features including a three-way storage
system that allows the engine to be laid on any side without fuel or oil
leaks, an overhead integral fuel tank that enables gravity-fed starting
even after long-term storage, and a redesigned tiller handle that
minimizes vibration transmission.
The engine's compact dimensions and lightweight construction, with the
S-shaft model weighing only 24.0 kg, make it exceptionally easy to
transport and operate. Whether powering small inflatables, yacht
tenders, or fishing dinghies, the Suzuki DF4A combines modern technology
with proven durability to elevate the small boat experience.
The Suzuki DF4A is built around a single-cylinder overhead valve
four-stroke powerhead utilizing a carbureted fuel delivery system. This
engine represents a complete redesign of Suzuki's portable outboard
lineup, achieving a one-kilogram weight reduction compared to previous
models while maintaining the same 138 cc displacement. The engine is
available in both short shaft and long shaft configurations to
accommodate different transom heights.
Engine Model: Suzuki DF4A
Engine Type: Single-cylinder, 4-stroke OHV gasoline outboard engine
Number of Cylinders: 1
Displacement: 8.42 cu in (138 cc)
Cylinder Bore: 2.38 in (60.4 mm)
Piston Stroke: 1.89 in (48.0 mm)
Maximum Engine Power: 3.9 hp (2.9 kW) at the propeller
Maximum Engine Speed: 4000-5000 RPM
Idle Speed: 1250-1350 RPM
Fuel System Type: Carburetor with manual choke
Fuel Pump Type: Mechanical
Fuel Type: Unleaded gasoline, 91 octane minimum
Fuel Tank Capacity: 1.1 quarts (1.0 liter) integral overhead tank
Lubrication System: Trochoid pump with forced lubrication and oil filter
Engine Oil Capacity: 0.75 quarts (0.70 liters)
Engine Oil Type: SAE 10W-30 or 10W-40
API Service Classifications: SH, SG, SJ, SM, SL, and SN
Cooling System: Water-cooled with thermostat
Ignition System: Digital CDI microcomputer
Starting System: Manual recoil start
Choke System: Manual
Electrical System Rating: 12 Volts
Charging System: Optional alternator
Alternator Rating: 12V 5A or 6A optional
Steering System: Tiller handle with vibration mitigation design
Gear Shift: Forward-Neutral-Reverse (F-N-R)
Gear Ratio: 1.92:1
Gear Oil Capacity: 0.20 quarts (0.19 liters)
Gear Lubricant Type: Suzuki Outboard Motor Gear Oil or GL5 SAE 90
Exhaust System: Through propeller hub
Trim System: Manual trim and tilt with five tilt pin positions
Transom Height (Short Shaft): 15 inches (381 mm)
Transom Height (Long Shaft): 20 inches (508 mm)
Outboard Weight (Short Shaft): 52.8 lbs (24.0 kg) dry weight
Outboard Weight (Long Shaft): 55 lbs (25.0 kg) dry weight
Spark Plug Type: NGK CPR6EA-9
Spark Plug Gap: 0.031-0.035 in (0.8-0.9 mm)
Valve Lash (Intake): 0.005-0.007 in (0.13-0.17 mm) cold
Valve Lash (Exhaust): 0.005-0.007 in (0.13-0.17 mm) cold
Emissions Compliance: CARB 3-Star, EU compliant, conforms to world's
strictest standards
The powerhead of the Suzuki DF4A features a single-cylinder block with
an overhead valve (OHV) design. The cylinder bore measures 60.4 mm, and
the piston stroke is 48.0 mm, contributing to the engine's 138 cc
displacement. An innovative offset crankshaft design positions the
crankshaft slightly off-center of the cylinder, reducing lateral
pressure against the cylinder wall as the piston moves up and down,
resulting in smoother piston movement and improved operating efficiency.
The valve train includes intake and exhaust valves with valve guides,
stem seals, valve springs, spring retainers, and valve cotters. Valve
lash for both intake and exhaust valves must be maintained at 0.13 to
0.17 mm cold, requiring periodic inspection and adjustment every 200
hours.
The cylinder head is secured with bolts torqued to 21.7 lb-ft (30 Nm)
with engine oil applied to the threads. The rocker arm design has been
modified to eliminate excessive play, contributing to reduced noise
levels. The crankshaft bearing utilizes a plane type rather than a
common ball type, further reducing noise and vibration.
The fuel system is centered around a carburetor with manual choke
control. A revolutionary overhead integral fuel tank with a capacity of
1.0 liter is positioned directly above the carburetor, enabling gravity
fuel supply without requiring a primer bulb or external tank. This
gravity-fed system allows the engine to start instantly right after
filling fuel, even after extended storage periods.
The fuel tank incorporates a one-way valve and redesigned fuel cap with
integrated venting. The fuel system includes a mechanical fuel pump and
an in-line fuel filter requiring inspection every 100 hours and
replacement every 400 hours. The breather and fuel lines must be checked
every 100 hours.
The new fuel system design, combined with the advanced lubrication
system, enables the three-way storage capability that allows the
outboard to be transported or stored on any of three sides (port,
starboard, or front) without fuel or oil leakage. The carburetor
requires inspection every 100 hours as part of routine maintenance.
Lubrication is managed by a trochoid pump providing forced lubrication
throughout the engine. The system incorporates an additional oil passage
to the upper and lower crankshaft and connecting rod big end, ensuring
all critical components receive adequate lubrication.
A first-in-its-class oil filter greatly increases the reliability of the
lubrication system. The oil pan has a capacity of 0.70 liters, and a
strategically positioned oil window allows for visual confirmation of
the actual lubricating condition.
Recommended engine oil is SAE 10W-30 or 10W-40 meeting API service
classifications SH, SG, SJ, SM, SL, or SN. Engine oil must be changed
every 100 hours of operation, with the oil filter replaced every 200
hours. The lubrication system, combined with the new fuel system design,
enables three-way storage without leakage concerns.
The cooling system is a water-cooled design with thermostat regulation
to maintain optimal operating temperature. A water pump, driven by the
driveshaft, circulates water from the surrounding environment through
cooling passages in the cylinder block and cylinder head. The thermostat
ensures rapid warm-up and stable temperature control during operation.
The system includes a fresh water flushing port for easy maintenance
after saltwater use. The thermostat must be checked every 100 hours as
part of routine maintenance. The water pump and water pump impeller
require inspection every 200 hours, with the impeller scheduled for
replacement every 300 hours to maintain proper cooling system
performance.
| Mid Section and Lower Unit |
The mid-section houses the driveshaft and exhaust tube, connecting the
powerhead to the lower unit. The exhaust system routes exhaust gases
through the propeller hub. The lower unit contains the gearcase with a
1.92:1 reduction ratio and forward-neutral-reverse shifting mechanism.
The gearcase has a lubricant capacity of 0.19 liters (0.20 quarts) and
requires Suzuki Outboard Motor Gear Oil or GL5 SAE 90 gear lubricant.
Gear oil must be changed every 100 hours of operation.
The propeller shaft incorporates an anode for corrosion protection, with
the propeller nut and pin requiring inspection every 100 hours. Suzuki's
Anti-Corrosion System provides extensive protection with a specially
developed anti-corrosion finish applied directly to the aluminum
surface, maximizing the bond and increasing protection for parts
constantly exposed to saltwater.
The Suzuki DF4A is equipped with manual trim and tilt adjustment. The
system features a tilt pin that can be repositioned in one of five holes
to achieve the desired trim angle. To adjust the trim angle, the motor
is locked in the fully tilted up position, the tilt pin is repositioned
in the desired holes, and the motor is lowered back down. Moving the pin
towards the boat lowers the bow, while moving the pin away from the boat
raises the bow.
Proper trim angle is essential for steering stability and performance;
an incorrect angle can cause the boat to plow, porpoise, or chine walk,
potentially resulting in loss of steering control. The tilt system
offers different up-and-down paths of the shallow drive arm compared to
previous models, with three locking positions when raised and smooth
lowering without locking.
Proper propeller selection is critical to allow the engine to operate
within its specified full-throttle RPM range of 4000 to 5000 RPM under
normal load conditions. The standard propeller for the DF4A is a
three-bladed aluminum propeller with a diameter of 7.5 inches (190 mm)
and a pitch of 6.5 inches (165 mm).
An alternative propeller with a 7-inch (178 mm) pitch is also available.
The propeller selection range is 6 to 7 inches of pitch. All propellers
for this model are three-blade type. The propeller nut and retaining pin
must be checked every 100 hours to ensure secure attachment.
Overall Weight (Short Shaft): 52.8 lbs (24.0 kg) dry weight, not
including propeller and engine oil
Overall Weight (Long Shaft): 55 lbs (25.0 kg) dry weight
Shaft Length (Short Shaft Model): 15 inches (381 mm)
Shaft Length (Long Shaft Model): 20 inches (508 mm)
Propeller Diameter: 7.5 inches (190 mm)
Propeller Pitch: 6.5 inches (165 mm) standard, 7 inches (178 mm)
optional
Every 100 Hours:
Change engine oil
Change gear oil
Check spark plug condition and gap
Check breather and fuel line condition
Check fuel filter for contamination
Check anodes for corrosion
Check thermostat operation
Check carburetor adjustment and condition
Check propeller nut and pin security
Every 200 Hours:
Replace oil filter
Check and adjust valve lash
Check and adjust idle speed
Check water pump operation
Check water pump impeller condition
Every 300 Hours:
Replace spark plug
Replace water pump impeller
Every 400 Hours:
Replace fuel filter
Recommended Fuel: Unleaded gasoline, 91 octane minimum RON
Recommended Engine Oil: SAE 10W-30 or 10W-40 meeting API SH, SG, SJ, SM,
SL, or SN
Engine Oil Capacity: 0.75 quarts (0.70 liters)
Recommended Gear Lubricant: Suzuki Outboard Motor Gear Oil or GL5 SAE 90
Gearcase Capacity: 0.20 quarts (0.19 liters)
Spark Plug Type: NGK CPR6EA-9
Spark Plug Gap: 0.031-0.035 in (0.8-0.9 mm)
Cylinder Head Bolts: 21.7 lb-ft (30 Nm) with engine oil applied to
threads
Propeller Nut: Consult service manual for specific torque value
Transom Mounting Bolts: Consult service manual for specific torque value
Spark Plugs: 15-22 lb-ft final torque
The Suzuki DF4A is a highly versatile powerplant suitable for a broad
spectrum of small boat types and boating activities. It is an ideal
choice for small inflatables, fishing dinghies, and yacht tenders up to
approximately 3.5 meters in length. The engine is perfect for
square-stern canoes or small sailboats needing a light auxiliary power
source. Its compact size and lightweight construction make it excellent
for camping and water trekking where portability and easy transport are
paramount.
The engine is well-suited for beginner boaters thanks to its simple
handling and reliable operation. The DF4A can be easily carried and
mounted by one person, making it ideal for solo boaters and those with
limited physical assistance. The integrated carrying handle in the lower
cover, combined with an additional front grip, provides convenient
two-handed carrying capability. With its four-stroke efficiency, the
engine sips fuel and runs cleanly, meeting all emission standards while
providing strong low-end torque for planing small boats.
The 180-degree steering capability allows the engine to swivel a full
circle for reverse thrust, enhancing maneuverability in tight quarters.
Whether navigating small lakes, exploring coastal waters, fishing
backwaters, or providing reliable auxiliary power, the Suzuki DF4A
offers the power, precision, and efficiency to elevate any small boat
experience.
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