Suzuki DF2.5 Specifications
| Engine Model: Suzuki DF2.5 |
| Engine Type: 4-stroke 1-cylinder OHV gasoline outboard engine |
| Total Displacement: 4.1 cu.in (68 cc) |
| Rated Engine Power: 2.5 Hp (1.8 kW) at 5750 rpm |
| Fuel System: Carburetor |
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The Suzuki DF2.5 is recognized for its
exceptional portability and ease of use, weighing a mere 13.0 kg.
Despite its small size, it incorporates advanced four-stroke technology,
offering cleaner operation and greater fuel efficiency than traditional
two-stroke engines of similar power. The engine features an integrated
0.9-liter fuel tank, positioned for gravity feed to the carburetor,
simplifying the starting procedure.
A twist-grip throttle on the tiller provides precise speed control. The
DF2.5 is engineered with Suzuki's focus on durability, including a
comprehensive anti-corrosion system for long life in marine
environments. Its compact dimensions and built-in carrying handle allow
for easy transport and storage, making it an ideal companion for small
watercraft.
Engine Model - Suzuki DF2.5
Engine Type - 4-stroke single-cylinder OHV gasoline outboard engine
Number of Cylinders - 1
Displacement - 68 cc (4.1 cu-in)
Cylinder Bore - 48.0 mm (1.89 in)
Piston Stroke - 38.0 mm (1.50 in)
Maximum Engine Power - 1.8 kW (2.5 hp)
Full Throttle Operating Range - 5250 - 5750 r/min
Idle Speed - 1800 - 2000 r/min (1900±100)
Compression Ratio - 9.0:1
Fuel System Type - Carburetor
Carburetor Model - Walbro LMJ-26
Fuel Type - Unleaded gasoline (91 octane minimum)
Ignition System - Transistorized
Cooling System - Water-cooled
Exhaust System - Through propeller hub
Starting System - Recoil starter
Choke System - Manual
Throttle Control - Twist grip
Gear Shift - Forward - Neutral
Reduction System - Bevel gear
Gear Ratio - 2.15:1
Steering System - Tiller
Trim and Tilt System - Manual, 4-position tilt pin
Transom Height (Short) - 381 mm (15 in)
Trim Angle Range - 6 to 20 degrees
Maximum Tilt Angle - 74 degrees
Dry Weight - 13.0 kg (28.7 lbs)
The powerhead is built around a single-cylinder configuration with a
displacement of 68 cc. It utilizes an OverHead Valve (OHV) design with
two valves per cylinder, one for intake and one for exhaust. The
cylinder bore inside diameter measures 48.000-48.015 mm, with a maximum
permissible out-of-round of 0.050 mm. The piston skirt diameter is
47.975-47.990 mm, resulting in a piston-to-cylinder clearance of
0.018-0.033 mm.
The piston pin outside diameter is 11.995-12.000 mm, with a piston pin
bore inside diameter of 12.002-12.008 mm, providing a clearance of
0.002-0.013 mm. The connecting rod big end inside diameter is
19.015-19.025 mm, with a crank pin outside diameter of 18.990-19.000 mm,
resulting in an oil clearance of 0.015-0.035 mm.
Connecting rod side clearance at the big end is 0.20-0.70 mm. The piston
rings include a top ring, second ring, and oil ring. The top and second
rings have a width of 1.21-1.23 mm and an end gap of 0.15-0.35 mm. The
top ring side clearance is 0.02-0.06 mm. The crankshaft maximum runout
is 0.050 mm.
The cylinder head incorporates the valve train components and combustion
chamber. The cylinder head warp limit is 0.050 mm. Valve head diameter
is 20.0 mm for the intake and 18.0 mm for the exhaust. Valve head
thickness for both valves is a minimum of 0.50 mm. The intake valve stem
outside diameter is 3.975-3.990 mm, while the exhaust valve stem is
3.960-3.975 mm. Valve guide inside diameter for both valves is
4.000-4.012 mm.
Intake valve stem-to-guide clearance is 0.010-0.037 mm, and exhaust
clearance is 0.025-0.052 mm. Valve seat width for both intake and
exhaust is 0.8-1.0 mm. The valve spring free length is 22.42 mm. Cam
height for both intake and exhaust lobes is 28.480-28.680 mm. Valve
lash, critical for proper engine timing, is set to 0.13-0.17 mm for both
the intake and exhaust valves.
The DF2.5 features a straightforward and reliable fuel delivery system
centered on a Walbro LMJ-26 carburetor. An integrated 0.9-liter fuel
tank is mounted directly on the engine, allowing for gravity feed to the
carburetor. This design simplifies operation and eliminates the need for
a separate remote fuel tank for many applications.
A manual choke is provided for cold starts. The twist-grip throttle
control on the tiller handle allows for smooth and precise engine speed
adjustment. The engine is designed to run on regular unleaded gasoline
with a minimum octane rating of 91.
The lubrication system is a wet sump design utilizing a trochoid pump to
circulate oil under pressure to critical engine components. This
pressurised system reduces friction and wear, enhancing the engine's
longevity.
The engine oil capacity is 0.38 liters (0.40 quarts) of SAE 10W-30 or
10W-40 oil, meeting API service classifications SE through SJ. The
engine incorporates a replaceable oil filter. The DF2.5 design allows
for convenient three-way storage without risk of oil leakage, a
significant advantage for a portable outboard.
Engine temperature is regulated by a water-cooled system. Cooling water
is drawn into the engine through intakes on the gearcase and circulated
by a rubber impeller water pump. A thermostat maintains the optimal
operating temperature for combustion efficiency and performance.
The system includes a fresh water flushing attachment, allowing owners
to easily flush the cooling passages with fresh water after use in salt
or polluted water, extending engine life. A tell-tale port provides a
visible indication that the cooling system is operational.
| Mid Section and Lower Unit |
The mid-section houses the driveshaft and provides the mounting
interface to the transom bracket. The lower unit contains the gearcase,
which is filled with 0.070 liters (0.073 quarts) of Suzuki Outboard
Motor Gear Oil or SAE 90 GL5 gear oil.
The gears provide a reduction ratio of 2.15:1, optimising propeller
speed for effective thrust. The shift mechanism enables engagement of
Forward and Neutral gears. Exhaust gases are expelled through the
propeller hub.
Trim and tilt adjustments are performed manually. The engine is fitted
with a manual tilt system that uses a pin in one of four adjustment
positions on the transom bracket.
This allows the operator to select the optimal trim angle between 6 and
20 degrees for the boat's running attitude under various load and water
conditions. A tilt release lever disengages the lock, allowing the
engine to be tilted to a maximum angle of 74 degrees for beaching,
trailering, or storage.
The DF2.5 is designed to use three-bladed aluminum propellers. The
propeller diameter is 188 mm (7.4 in). To accommodate different boat and
loading conditions, two primary propeller pitches are available: 115 mm
(4.5 in) and 135 mm (5.4 in).
The 4.5-inch pitch propeller provides more low-end thrust for heavier
loads, while the 5.4-inch pitch propeller is suited for lighter
applications where higher speed is desired.
The overall length is 437.0 mm (17.2 in), overall width is 262.0 mm
(10.3 in), and overall height is 963.0 mm (37.9 in). Designed for a 381
mm (15 in) transom, the engine has a dry weight of only 13.0 kg (28.7
lbs).
Every 100 hours of operation or annually, the following tasks should be
performed: change engine oil, change gear oil, check and clean the spark
plug (adjusting the gap to 0.6-0.7 mm or 0.024-0.028 in), inspect the
fuel line and breather, check the fuel filter, inspect the condition of
the sacrificial anodes, verify thermostat operation, and check the
carburetor, propeller nut, and cotter pin.
Every 200 hours, in addition to the 100-hour checks, the engine requires
inspection and adjustment of valve lash, checking and adjusting the idle
speed, and inspecting the water pump and its impeller.
Every 300 hours, the spark plug should be replaced with an NGK CR6HSA,
and the water pump impeller must be replaced to prevent cooling system
failure.
Cylinder head bolt - 13 Nm (9.5 lb-ft)
Conrod cap bolt - 7 Nm (5.0 lb-ft)
Crankcase bolt - 11 Nm (8.0 lb-ft)
Cylinder head cover bolt - 7 Nm (5.0 lb-ft)
Flywheel nut - 45 Nm (32.5 lb-ft)
Spark plug - 10-12 Nm (7.5-9.0 lb-ft)
Valve adjusting lock nut - 7 Nm (5.0 lb-ft)
Intake pipe bolt - 11 Nm (8.0 lb-ft)
Carburetor mounting bolt - 10 Nm (7.0 lb-ft)
Engine oil drain plug - 10 Nm (7.0 lb-ft)
Gearcase bolt - 8 Nm (6.0 lb-ft)
Water pump case bolt - 5 Nm (3.5 lb-ft)
Propeller shaft bearing housing bolt - 8 Nm (6.0 lb-ft)
Swivel shaft nut - 10 Nm (7.0 lb-ft)
Tiller handle pivot bolt - 17 Nm (12.5 lb-ft)
The Suzuki DF2.5 is engineered for the smallest watercraft. Its
ultra-lightweight and portable nature make it an ideal primary power
source for small inflatable boats, dinghies, canoes, and kayaks. It is
also a popular and dependable choice as an auxiliary motor for small
sailboats, providing maneuvering capability in harbors and a backup
power source. With its 2.5 hp output, it is well-suited for recreational
boaters seeking an efficient, quiet, and reliable outboard for tender
duties and sheltered waters.
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