Suzuki DF15 Specifications
| Engine Model: Suzuki DF15 |
| Engine Type: 4-stroke 2-cylinder SOHC gasoline outboard engine |
| Total Displacement: 18.4 cu.in (302 cc) |
| Rated Engine Power: 15 Hp (11 kW) at 6000 rpm |
| Fuel System: Carburetor |
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The Suzuki DF15 is recognized for its
lightweight and compact design, which has been achieved through
extensive engineering refinements to make it easier to carry and
transport than its predecessors. The engine is built with a focus on
fuel efficiency, leveraging Suzuki's four-stroke technology to deliver
greater range on less fuel. Its operation is noted for quiet
performance, aided by through-propeller hub exhaust, contributing to a
more comfortable boating experience.
The engine is available in both manual and electric start
configurations, as well as short and long shaft lengths to accommodate
various transom heights. Built with Suzuki's anti-corrosion system, it
is suitable for use in both freshwater and saltwater environments, with
features like a freshwater flush port for easy maintenance after
saltwater use. It is an ideal power source for small fishing boats, jon
boats, tenders, and inflatable craft.
Engine Model - Suzuki DF15, DF15E, DF15R
Engine Type - 4-stroke two-cylinder SOHC gasoline outboard engine
Number of Cylinders - 2
Displacement - 302 cc (18.4 cu-in)
Cylinder Bore - 58.0 mm (2.28 in)
Piston Stroke - 57.0 mm (2.24 in)
Maximum Engine Power - 11.0 kW (15.0 hp)
Full Throttle Operating Range - 5400 - 6000 r/min
Idle Speed - 850 - 950 r/min (900±50)
Compression Ratio - 9.0:1
Fuel System Type - Carburetor
Carburetor Model - Keihin BCM 23-11.5
Fuel Type - Unleaded gasoline (87 or 91 octane minimum)
Ignition System - Digital CDI
Cooling System - Water-cooled
Exhaust System - Through propeller hub
Starting System - Manual recoil or electric
Choke System - Manual or automatic
Throttle Control - Twist grip or remote control
Gear Shift - Forward - Neutral - Reverse
Gear Ratio - 2.08:1
Steering System - Tiller Handle or Remote Control
Trim and Tilt System - Manual, 5 tilt pin positions
Transom Height (Short Shaft) - 381 mm (15 in)
Transom Height (Long Shaft) - 508 mm (20 in)
Trim Angle - 4-20 degrees
Maximum Tilt Angle - 67 degrees
Dry Weight (Short Shaft, Manual) - 44.0 kg (97.0 lbs)
Dry Weight (Short Shaft, Electric) - 46.5 kg (102.5 lbs)
Dry Weight (Long Shaft, Manual) - 45.0 kg (99.0 lbs)
Dry Weight (Long Shaft, Electric) - 47.5 kg (104.7 lbs)
Alternator Rating - 12V 6A (12A on some models)
The powerhead is constructed around an inline two-cylinder configuration
with a displacement of 302 cc. The engine is a direct water-cooled,
4-stroke cycle gasoline unit with SOHC valve mechanism. The cylinder
bore inside diameter measures 58.000-58.015 mm, with a maximum
permissible out-of-round of 0.050 mm. The piston skirt diameter is
57.965-57.980 mm, resulting in a piston-to-cylinder clearance of
0.0271-0.0425 mm.
The piston pin outside diameter is 13.995-14.000 mm, with a piston pin
bore inside diameter of 14.002-14.008 mm, providing a clearance of
0.002-0.013 mm. The connecting rod big end inside diameter is
29.025-29.034 mm, with a crank pin outside diameter of 28.989-29.000 mm,
resulting in an oil clearance of 0.025-0.045 mm. Connecting rod side
clearance at the big end is 0.10-0.20 mm.
The crankshaft journal outside diameter is 31.989-32.000 mm with an oil
clearance of 0.020-0.047 mm. Maximum crankshaft runout is 0.040 mm and
crankshaft thrust play is 0.6 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. The top and second ring end gap is 0.10-0.25 mm. Top and
second ring side clearance is 0.02-0.06 mm. The engine mounting utilizes
a shear mount design to isolate and dampen vibration from the hull.
The cylinder head incorporates a Single OverHead Camshaft (SOHC) valve
train with two valves per cylinder. The SOHC is mounted over the
cylinder head and driven by the crankshaft through a timing belt (cogged
belt). Unlike conventional overhead valve (OHV) engines, this design has
no push rods, allowing valve movement to follow crankshaft rotation
without delay.
The cylinder head warp limit is 0.050 mm. Intake valve head diameter is
26.0 mm, and exhaust valve head diameter is 22.0 mm. Minimum valve head
thickness for both valves is 0.50 mm. The intake valve stem outside
diameter is 5.475-5.490 mm, while the exhaust valve stem is 5.450-5.465
mm. Valve guide inside diameter for both valves is 5.500-5.512 mm.
Intake valve stem-to-guide clearance is 0.010-0.037 mm, and exhaust
clearance is 0.035-0.062 mm.
Valve seat width for both intake and exhaust is 0.9-1.1 mm. The valve
spring free length is 32.52 mm. Intake cam height is 23.394-23.454 mm,
and exhaust cam height is 23.397-23.457 mm. Camshaft journal outside
diameter is 24.959-24.980 mm for the upper journal and 22.959-22.980 mm
for the lower, with an oil clearance of 0.020-0.062 mm. Valve clearance
is set to 0.18-0.22 mm for both intake and exhaust valves.
The DF15 features a reliable carburetted fuel delivery system using a
single Keihin BCM 23-11.5 carburetor. A mechanical fuel pump draws fuel
from a standard 12-liter external fuel tank included with the engine.
For cold starts, a choke system is employed - manual for the standard
models and automatic on some electric-start variants.
The fuel system also includes a fuel filter that requires periodic
inspection. The engine is designed to run on unleaded gasoline with a
minimum octane rating of 87. A twist-grip throttle on tiller models
allows for smooth and precise engine speed control, while remote control
models interface with the boat's control system.
The lubrication system is a pressure-fed wet sump design utilizing a
trochoid-type cam-driven oil pump to ensure reliable oil delivery to all
critical engine components. This pressurised system reduces friction and
wear, enhancing engine longevity. The engine includes a replaceable
cartridge-style oil filter.
Engine oil capacity is 1.00 liter for oil change only, and 1.1 liters
when the oil filter is also changed. It requires SAE 10W-40 oil meeting
API service classifications SG, SH, SJ, SL, or SM. A low oil pressure
warning system protects the engine from operation with insufficient oil
pressure. An oil level check is facilitated through a dipstick.
Engine temperature is regulated by a water-cooled system with a
thermostat. Cooling water is drawn into the engine through intakes on
the gearcase and circulated by a rubber impeller water pump. A
thermostat maintains optimal operating temperature for combustion
efficiency and performance. The system includes a fresh water flushing
port, allowing owners to easily flush cooling passages with fresh water
after use in salt or polluted water.
An overheat warning system alerts the operator to cooling system
malfunctions. A tell-tale port provides visible confirmation that the
cooling system is operational. When operating in freezing weather, the
lower unit should remain submerged or the engine should be stored
vertically to allow complete drainage of the cooling system.
| Mid Section and Lower Unit |
The mid-section houses the driveshaft and provides the mounting
interface to the transom bracket via the engine mounting system. The
lower unit contains the gearcase, which is filled with 170 ml of Suzuki
Outboard Motor Gear Oil or GL5 SAE 90 gear oil.
The gears provide a reduction ratio of 2.08:1 (12:25), optimizing
propeller speed for effective thrust. The shift mechanism enables smooth
and positive engagement of Forward, Neutral, and Reverse gears. Exhaust
gases are expelled through the propeller hub for quieter operation.
Trim and tilt adjustments are performed manually with 5 tilt pin
positions. The manual tilt system uses a pin in one of several
adjustment positions on the transom bracket, allowing the operator to
select the optimal trim angle for the boat's running attitude under
various load and water conditions. The trim angle range is 4-20 degrees,
with a maximum tilt angle of 67 degrees.
A tilt release lever disengages the lock for tilting the engine out of
the water for beaching, trailering, or storage. For shallow water
operation, the engine may be tilted higher than normal trim angles, but
operation should be limited to slow speeds and operation above 1500
r/min should be avoided.
The DF15 is designed to use three-bladed aluminum propellers with a
spline drive rubber hub. The propeller diameter is 235 mm (9.25 in). A
wide range of propeller pitches is available from 7 inches to 11 inches
to accommodate different boat and loading conditions.
Available propeller options include 7, 8, 9, 10, and 11-inch pitches.
Selecting the correct pitch is crucial for allowing the engine to
operate within its recommended full-throttle RPM range of 5400-6000 for
optimal performance and efficiency.
The overall length is 668.0 mm (26.3 in), overall width is 323.0 mm
(12.7 in). The short shaft model, designed for a 381 mm (15 in) transom,
has an overall height of 1095.0 mm (43.1 in) and a dry weight of 44.0 kg
(97.0 lbs) for the manual start version.
The electric start short shaft model weighs 46.5 kg (102.5 lbs). The
long shaft model, for a 508 mm (20 in) transom, has an overall height of
1220.0 mm (48.0 in) and a dry weight of 45.0 kg (99.0 lbs) with manual
start. The electric start long shaft version weighs 47.5 kg (104.7 lbs).
Every 100 hours of operation or 12 months, the following tasks should be
performed: change engine oil, change gear oil, check and clean the spark
plug (adjusting the gap to 0.7-0.8 mm or 0.028-0.031 in), inspect the
fuel line and breather for leaks or cracks, check the fuel filter,
inspect the condition of the sacrificial anodes, verify thermostat
operation, check the carburetor, and check the propeller nut and cotter
pin. On electric start models, the battery should also be checked.
Every 200 hours, in addition to the 100-hour checks, the engine requires
replacement of the oil filter, inspection and adjustment of valve
clearance, inspection of the timing belt, checking and adjusting the
idle speed, inspecting the water pump and its impeller, and replacement
of the spark plug.
Every 400 hours, the in-line fuel filter should be replaced. Engine oil
capacity is 1.00 liter (1.1 US qt) of SAE 10W-40 oil meeting API SG
through SM. Gearcase capacity is 0.17 L (5.7 US oz) of Suzuki Outboard
Motor Gear Oil or GL5 SAE 90. Spark plug type is NGK CPR6EA-9 with a gap
of 0.7-0.8 mm. Valve clearance (cold) is 0.18-0.22 mm for both intake
and exhaust. Ignition timing is 5-30 degrees BTDC.
Cylinder head bolt - 27 Nm (20.0 lb-ft)
Cylinder head cover bolt - 10 Nm (7.0 lb-ft)
Crankcase bolt (6 mm) - 14 Nm (10.0 lb-ft)
Crankcase bolt (8 mm) - 25 Nm (18.0 lb-ft)
Connecting rod cap bolt - 12 Nm (8.5 lb-ft)
Flywheel nut - 80 Nm (58.0 lb-ft)
Spark plug - 27 Nm (19.5 lb-ft)
Valve adjusting lock nut - 11 Nm (8.0 lb-ft)
Intake manifold bolt - 23 Nm (16.5 lb-ft)
Carburetor mounting bolt - 10 Nm (7.0 lb-ft)
Fuel pump mounting bolt - 10 Nm (7.0 lb-ft)
Engine oil drain plug - 13 Nm (9.5 lb-ft)
Power unit mounting bolt - 23 Nm (16.5 lb-ft)
Clamp bracket shaft nut - 43 Nm (31.0 lb-ft)
Tiller handle cover bolt - 17 Nm (12.5 lb-ft)
Gearcase bolt - 23 Nm (16.5 lb-ft)
Propeller nut - 18 Nm (13.0 lb-ft)
Water pump case bolt - 18 Nm (13.0 lb-ft)
Camshaft pulley bolt - 10 Nm (7.0 lb-ft)
Timing pulley nut - 50 Nm (36.0 lb-ft)
The Suzuki DF15 is engineered for a wide variety of small watercraft.
Its compact size, light weight, and reliable performance make it an
ideal primary power source for small fishing boats, aluminum boats, jon
boats, dinghies, and inflatable craft including RIBs. It is a popular
and dependable choice as an auxiliary motor for larger fishing boats or
sailboats, providing reliable power and maneuverability.
With its 15 hp output and efficient four-stroke design, it is
well-suited for recreational boaters and anglers seeking an efficient,
quiet, and reliable outboard for various water conditions. The engine is
saltwater rated and suitable for use in both freshwater and saltwater
environments when properly maintained.
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