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Tohatsu MFS15E Specifications
| Engine Model: Tohatsu MFS15E |
| Engine Type: 4-stroke 2-cylinder SOHC gasoline outboard engine |
| Total Displacement: 20.3 cu.in (333 cc) |
| Rated Engine Power: 15 Hp (11 kW) at 6000 rpm |
| Fuel System: Fuel Injection |
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| General Technical Data |
The Tohatsu MFS15E is a two-cylinder,
four-stroke outboard delivering 15 horsepower. Available in several
configurations - including manual start with tiller (MF), electric start
with tiller (EF, EFT), and electric start with remote control (EP, EPT)
- this engine represents the latest evolution in portable four-stroke
technology.
It is engineered with a battery-less electronic fuel injection system,
making it the lightest model in its class while delivering exceptional
torque and top-speed performance. The design focuses on advanced fuel
injection technology, offering features like a digital ECU for immediate
starting, a high-output alternator, and significantly reduced vibration
for a smoother and quieter ride.
The Tohatsu MFS15E is a technologically advanced and dependable
four-stroke outboard. Its two-cylinder design provides exceptionally
smooth operation with outstanding fuel efficiency, a direct benefit of
its advanced electronic fuel injection system and increased
displacement. The engine is built with high-grade marine aluminum alloy
and features zinc-coated internal water passages, providing superior
corrosion resistance and longevity, especially in saltwater
environments.
An Electronic Control Unit (ECU) manages the fuel injection and ignition
systems, ensuring immediate engine starting in all conditions without
the need for a choke, quicker throttle response, and smoother trolling.
The availability of power trim and tilt on select models adds to its
user-friendly nature, and features like low oil pressure and overheat
warnings provide essential operational security.
Engine Model: Tohatsu MFS15E MF, EF, EFT, EP, EPT.
Engine Type: 4-Stroke.
Number of Cylinders: 2.
Bore x Stroke: 61 mm x 57 mm (2.40 in x 2.24 in).
Piston Displacement: 333 cc (20.3 cu in).
Power Output: 11 kW (15 HP).
Full Throttle Operating Range: 5400-6100 r/min.
Idle Speed in Neutral Gear: 950 r/min.
Minimum Trolling Speed in Forward Gear: 950 r/min.
Fuel System: Electronic Fuel Injection (FI).
Fuel Priming System: ECU (Electronic Control Unit) controlled.
Fuel Pumping System: Mechanical (plunger) pump plus electric system
within VST.
Exhaust System: Through-the-propeller hub exhaust.
Cooling System: Water cooling with thermostat control.
Lubrication System: Wet sump with trochoid pump.
Starting System: Manual (MF model) / Electric starter motor (EF, EFT,
EP, EPT models).
Ignition System: CDI (Capacitor Discharge Ignition) with digital ECU
control.
Spark Plugs: NGK DCPR6E.
Alternator Output: 12V, 145W, 12A (standard on electric start models).
Steering (MF, EF, EFT): Tiller Handle.
Steering (EP, EPT): Remote Control.
Steering Angle: 45 degrees each side, 90 degrees total.
Trim System (MF, EF, EP): Manual trim and tilt.
Trim System (EFT, EPT): Power trim and tilt.
Trim Position (MF, EF, EP): 6.
Trim Position (EFT, EPT): 5.
Trim Angle (MF, EF, EP): -8 to +12 degrees.
Trim Angle (EFT, EPT): -8 to +8 degrees.
Tilt Up Angle: 76 degrees.
Gear Shift: Dog clutch (F-N-R).
Gear Reduction Ratio: 2.15 (13:28).
Type of Gears: Spiral Bevel Gear.
Propeller Shaft Driving: Spline.
Standard Propeller Pitch: Short shaft 10 inches, Long and Ultra Long
shaft 9 inches.
Propeller Selection Range: 6 to 11.5 inches of pitch.
Fuel: Unleaded Regular Gasoline with an anti-knock index (R+M/2) of 87
or higher, or a Research Octane Number (RON) of 90 or higher.
Fuel Tank Capacity: 12 L (3.2 US gal) separate fuel tank.
Engine Oil: API SH, SJ, SL SAE 10W-30 or 10W-40, NMMA Certified FC-W.
Engine Oil Capacity: 1.2 L (1.26 qt) with filter change; 1.0 L (1.05 qt)
without filter change.
Gear Oil: API GL-5, SAE 80-90.
Gear Oil Capacity: 0.47 L (0.49 qt).
| Powerhead |
The MFS15E features a single overhead camshaft (SOHC), two-cylinder powerhead. The four-stroke cycle contributes to its clean and efficient operation. The engine utilizes a timing belt to drive the camshaft, which actuates the valves via rocker arms. It is built with a high-grade marine aluminum alloy for the block and other components, providing excellent corrosion resistance and durability while keeping weight low.
Critical internal dimensions include a crankpin outside diameter of 28.972 to 28.985 mm (1.1406 to 1.1411 in), a main journal outside diameter of 33.988 to 33.996 mm (1.3381 to 1.3384 in), and a piston outside diameter of 60.960 mm (2.4000 in).
Piston ring end gaps are specified as 0.15 to 0.30 mm (0.0059 to 0.0118 in) for the top ring, 0.35 to 0.50 mm (0.0138 to 0.0197 in) for the second ring, and 0.20 to 0.70 mm (0.0079 to 0.0276 in) for the oil ring. Intake valve clearance is set at 0.13 to 0.17 mm (0.0051 to 0.0067 in), while exhaust valve clearance is 0.18 to 0.22 mm (0.0071 to 0.0087 in).
| Fuel System |
The fuel system features a battery-less electronic fuel injection
system, a significant advancement for portable outboards. This system
precisely meters fuel for optimal combustion, resulting in improved fuel
economy, easier starting without choke operation, and reduced emissions.
It is designed to run on standard 87-octane unleaded gasoline.
A separate 12-liter fuel tank is provided with the outboard. The system
includes a newly designed, user-friendly fuel water separator with a
tool-free drain for easy maintenance. The Vapor Separator Tank (VST)
integrates the high-pressure fuel pump, regulator, and fuel cooler into
a single component.
| Lubrication System |
The lubrication system is a forced, wet-sump design utilizing a trochoid
oil pump. The engine oil is contained in a sump within the engine and is
circulated under pressure to lubricate internal components.
The oil level must be checked regularly using a dipstick and maintained
between the upper and lower level marks. The recommended oil is a
high-quality 4-stroke outboard oil, such as API class SH, SJ, or SL, SAE
10W-30 or 10W-40. A convenient canister-style oil filter allows for easy
replacement.
| Cooling System |
Cooling is managed by a forced water system that is thermostatically
controlled to maintain a consistent engine temperature for optimal
performance and longevity. The system features a water pump with a
durable stainless steel housing liner for outstanding reliability.
An overheat warning system (visual and audible on remote models) alerts
the operator if the engine approaches a critical temperature. A low oil
pressure warning system is also provided.
| Mid Section and Lower Unit |
The MFS15E is fitted with a durable mid section and lower unit housing a
forward-neutral-reverse dog clutch. The gear reduction ratio is 2.15:1
(13:28). The gears are of the spiral bevel type. The recommended gear
oil is an API GL-5, SAE 80-90 grade, with a total capacity of 0.47
liters.
The lower unit is equipped with a replaceable trim tab, which also
serves as a sacrificial anode for corrosion protection. The
through-the-prop exhaust system contributes to quieter operation.
| Trim and Tilt System |
The MFS15E is offered with two types of trim systems. The MF, EF, and EP
models feature a manual trim and tilt system with six trim positions,
adjustable from -8 to +12 degrees. The EFT and EPT models are equipped
with a power trim and tilt system, offering five trim positions
adjustable from -8 to +8 degrees.
The power trim system provides added convenience for adjusting motor
angle and includes a manual relief valve for emergency operation. The
maximum tilt-up angle is 76 degrees. A shallow water drive feature is
also standard, allowing operation in very shallow water.
| Propeller Information |
The recommended propeller selection range for the MFS15E is from 6 to 11.5 inches of pitch. Standard propeller pitches are 10 inches for short shaft models and 9 inches for long and ultra-long shaft models.
The correct propeller must be selected so that the engine operates within its wide-open throttle (WOT) range of 5400-6100 r/min under a normal load for optimal performance and engine longevity. The propeller shaft is driven by splines, and the standard propeller is made of aluminum.
| Dimensions and Weight |
Overall Length (Tiller Handle models): 1038 mm (40.9 in)
Overall Length (Remote Control models): 635 mm (25.0 in)
Overall Width (Manual Tilt models): 343 mm (13.5 in)
Overall Width (Power Tilt models): 339 mm (13.4 in)
Overall Height (Short Shaft): 1116 mm (43.9 in)
Overall Height (Long Shaft): 1258 mm (49.5 in)
Overall Height (Ultra Long Shaft): 1386 mm (54.5 in)
Transom Height (Short Shaft): 413 mm (16.3 in)
Transom Height (Long Shaft): 562 mm (22.1 in)
Transom Height (Ultra Long Shaft): 689 mm (27.1 in)
Weight (MF Short Shaft): 43 kg (95 lb)
Weight (EF Short Shaft): 47 kg (104 lb)
Weight (EFT Short Shaft): 52.5 kg (116 lb)
Weight (EP Short Shaft): 51.5 kg (114 lb)
Weight (EPT Short Shaft): 46 kg (101 lb)
Weight (MF Long Shaft): 44 kg (97 lb)
Weight (EF Long Shaft): 48 kg (106 lb)
Weight (EFT Long Shaft): 53.5 kg (118 lb)
Weight (EP Long Shaft): 52.5 kg (116 lb)
Weight (EPT Long Shaft): 47 kg (104 lb)
Weight (MF Ultra Long Shaft): 45.5 kg (100 lb)
Weight (EF Ultra Long Shaft): 49.5 kg (109 lb)
Weight (EFT Ultra Long Shaft): 55 kg (121 lb)
Weight (EP Ultra Long Shaft): 54 kg (119 lb)
Weight (EPT Ultra Long Shaft): 48.5 kg (107 lb)
| Maintenance Data |
First 20 Hours / 1 Month: Initial dealer inspection. Every 50 Hours / 3
Months: Check and clean the fuel filter and fuel water separator.
Inspect spark plugs and adjust gap as needed. Check and re-tighten all
accessible bolts and nuts. Apply grease to all sliding and rotating
parts and grease nipples. Check engine oil level.
Every 100 Hours / 6 Months: Change engine oil and oil filter. Change
gear oil, inspecting for water or metal particles. Have a dealer check
valve clearance and ignition timing. Inspect the water pump impeller for
wear. Annually / Every 100 Hours: Replace the water pump impeller
regardless of apparent condition. Replace spark plugs. Replace timing
belt (by dealer).
| Tightening Torques |
Cylinder Head Cover Bolt: 6 Nm (4 lb-ft)
Cylinder Head Bolt (M8x1.25): First 10 Nm (7 lb-ft), Final 30 Nm (22
lb-ft)
Cylinder Head Bolt (M6x1.0): First 6 Nm (4 lb-ft), Final 10 Nm (7 lb-ft)
Spark Plug: 18 Nm (13 lb-ft)
Exhaust Cover Bolt: 9 Nm (7 lb-ft)
Connecting Rod Bolt: 10 Nm (7 lb-ft)
Flywheel Nut: 58 Nm (43 lb-ft)
Oil Filter: 18 Nm (13 lb-ft)
Oil Pressure Switch: 8 Nm (6 lb-ft)
Oil Pump Assy Bolt: 6 Nm (4 lb-ft)
Power Unit Bolt: 30 Nm (22 lb-ft)
Engine Oil Drain Bolt: 24 Nm (17 lb-ft)
Gear Case Oil Plug: 4 Nm (3 lb-ft)
Propeller Shaft Housing Bolt: 6 Nm (4 lb-ft)
Pump Case Bolt: 6 Nm (4 lb-ft)
Gear Case Bolt: 24 Nm (17 lb-ft)
Propeller Nut: 12 Nm (9 lb-ft)
| Boat Applications |
The Tohatsu MFS15E is designed for a wide variety of small boats, where its four-stroke efficiency, light weight, and quiet operation are advantageous. Ideal applications include: Fishing Boats: An excellent choice for small aluminum tiller-steered boats, jon boats, and lightweight center consoles, where its light weight and easy starting are highly valued.
Utility Boats: Well-suited for skiffs, inflatables, and other light commercial or recreational utility craft used in sheltered waters. Auxiliary Power: Can serve as reliable auxiliary power for larger sailing yachts, with the high-output alternator providing excellent battery charging capability. Dinghies: Ideal power for yacht tenders and dinghies due to its portable weight and fuel efficiency.
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