Tohatsu M50D2 Specifications
| Engine Model: Tohatsu M50D2 |
| Engine Type: 2-stroke 3-cylinder gasoline outboard engine |
| Total Displacement: 42.5 cu.in (697 cc) |
| Rated Engine Power: 50 Hp (37 kW) at 5500 rpm |
| Fuel System: Carburetor |
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The Tohatsu M50D2 is a three-cylinder,
loop-charged two-stroke outboard delivering 50 horsepower. Offered in
multiple configurations - including manual start with tiller handle
(MF), electric start with tiller (EFTO), remote electric start with
manual tilt (EPO), and remote electric start with power trim and tilt
(EPTO) - this engine builds upon the proven platform shared with the
M40D2. It is renowned for an exceptional power-to-weight ratio and
renowned reliability, making it a popular choice for boaters requiring a
robust yet lightweight powerplant for small to medium-sized vessels.
The Tohatsu M50D2 represents a well-engineered and dependable outboard
option. Its in-line three-cylinder design provides smooth operation with
good fuel economy, a direct benefit of its loop-charged induction
system. Users appreciate the engine's straightforward design, which
contributes to its reputation for reliability. A key strength across
multiple models is the availability of features like an 11-amp
alternator for powering electronics and an optional power trim and tilt
system.
The engine is built with corrosion-resistant materials, including
high-grade marine aluminum alloy and zinc-coated internal water
passages, enhancing its longevity, especially in saltwater environments.
An Electronic Safety Governor protects the engine from over-revving by
limiting RPM, while an overheat warning and water pressure sensor
provide additional operational security.
Engine Model: Tohatsu M50D2 MF, EFTO, EPO, EPTO.
Engine Type: 2-Stroke.
Number of Cylinders: 3.
Bore x Stroke: 68 mm x 64 mm (2.68 in x 2.52 in).
Piston Displacement: 697 cc (42.53 cu in).
Power Output: 37.0 kW (50 HP).
Full Throttle Operating Range: 5150-5850 r/min.
Idle Speed in Neutral Gear: 900 r/min.
Minimum Trolling Speed in Forward Gear: 750 r/min.
Exhaust System: Through-hub exhaust.
Cooling System: Water cooling with thermostat control
Starting System: Manual (MF model) / Electric starter motor (EFTO, EPO,
EPTO models).
Ignition System: Flywheel Magneto CDI (Capacitor Discharge Ignition).
Spark Plug: NGK B8HS-10 or BR8HS-10 (for M50D2).
Spark Plug Gap: 0.9-1.0 mm (0.035-0.039 in).
Alternator: 12V, 130W, 11A (Standard on electric start models, optional
on manual start).
Trim System: Manual trim and tilt (MF, EPO models) / Power trim and tilt
(EFTO, EPTO models).
Steering Angle (MF, EPO): 80 degrees.
Steering Angle (EFTO, EPTO): 70 degrees.
Trim Angle (MF, EPO): -8 to 12 degrees.
Trim Angle (EFTO, EPTO): -4 to 14 degrees.
Trim Position (MF, EPO): 6.
Trim Position (EFTO, EPTO): 4.
Tilt Up Angle (MF, EPO): 63 degrees.
Tilt Up Angle (EFTO, EPTO): 62 degrees.
Gear Shift: Dog clutch (F-N-R).
Gear Reduction Ratio: 1.85 (13:24).
Fuel: Unleaded Regular Gasoline with an anti-knock index (R+M/2) of 87
or higher, or a Research Octane Number (RON) of 91 or higher.
Fuel Tank Capacity: 25 L (6.6 US gal) Separate fuel tank.
Engine Oil: Genuine two-stroke engine oil or NMMA certified TC-W3
outboard oil.
Engine Oil Mixing Ratio: 50:1 (Pre-mix for manual start models) /
Auto-mixing for specific electric start models. Gear Oil: API GL-5, SAE
80-90.
Gear Oil Capacity: 0.5 L (16.9 US fl oz / 17.6 Imp fl oz).
PTT Fluid (EFTO, EPTO): ATF (Automatic Transmission Fluid) Dexron III..
The M50D2 features a loop-charged, three-cylinder powerhead. Loop
charging is a highly efficient scavenging method that directs the
fuel-air mixture in a loop to push out exhaust gases, resulting in
smoother operation and improved fuel economy compared to older
cross-flow designs.
The engine 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. The CD ignition system contributes
to quick and reliable starts.
The fuel system is carbureted. It is designed to run on standard
87-octane unleaded gasoline. A separate 25-liter fuel tank is provided
with the outboard. The system includes a fuel filter located on the
engine that requires periodic inspection and cleaning.
The lubrication system varies by model. The base manual start (MF) model
requires fuel pre-mixed at a 50:1 ratio. Many electric start versions,
such as the EPO and EPTO, feature Tohatsu's automixing oil injection
system for optimum lubrication under varying loads, which simplifies
refueling.
For these automixing models, a 2-liter engine oil tank is located
conveniently on top of the motor for easy refills. During the 10-hour
break-in period, a richer fuel mixture is recommended: a 25:1 pre-mix
ratio for pre-mix models, and a 50:1 pre-mix in addition to the
automixing system for oil-injected models.
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 for outstanding reliability.
An overheat warning (audible alarm) alerts the operator if the engine
approaches a critical temperature. A water pressure sensor is also
incorporated into the system.
| Mid Section and Lower Unit |
The M50D2 is fitted with a durable mid section and lower unit housing a
forward-neutral-reverse dog clutch. The gear reduction ratio is 1.85:1
(13:24). The recommended gear oil is an API GL-5, SAE 80-90 grade, with
a total capacity of 0.5 liters.
The lower unit is equipped with a replaceable trim tab, which also
serves as a sacrificial anode for corrosion protection. The through-hub
exhaust system contributes to quieter operation.
The M50D2 is offered with two types of trim systems. The MF and EPO
models feature a manual trim and tilt system with six trim positions.
This system includes a reverse lock lever and a thrust rod for shallow
water drive.
The EFTO and EPTO models are equipped with a power trim and tilt system,
which uses electric hydraulic pumps to adjust the motor's angle. This
system uses Dexron III Automatic Transmission Fluid and has a manual
relief valve for emergency operation.
The recommended propeller selection range for the M50D2 is from 7 to 15
inches of pitch. The correct propeller must be selected so that the
engine operates within its wide-open throttle (WOT) range of 5150-5850
r/min under a normal load for optimal performance and engine longevity.
A worn or bent propeller will lower motor performance and can cause
engine trouble.
Overall Length (MF, EFTO): 1143 mm (45.0 in)
Overall Length (EPO, EPTO): 630 mm (24.8 in)
Overall Width (MF, EFTO): 384 mm (15.1 in)
Overall Width (EPO, EPTO): 345 mm (13.6 in)
Overall Height (Short Shaft MF/EFTO): 1225 mm (48.2 in)
Overall Height (Short Shaft EPO/EPTO): 1192 mm (46.9 in)
Overall Height (Long Shaft MF/EFTO): 1352 mm (53.2 in)
Overall Height (Long Shaft EPO/EPTO): 1319 mm (51.9 in)
Transom Height (Short Shaft): 403 mm (15.9 in)
Transom Height (Long Shaft): 530 mm (20.9 in)
Weight (Short Shaft MF): 72 kg (159 lb)
Weight (Short Shaft EFTO): 87.5 kg (193 lb)
Weight (Short Shaft EPO): 74.5 kg (164 lb)
Weight (Short Shaft EPTO): 83.5 kg (184 lb)
Weight (Long Shaft MF): 73.5 kg (162 lb)
Weight (Long Shaft EFTO): 89 kg (196 lb)
Weight (Long Shaft EPO): 76 kg (168 lb)
Weight (Long Shaft EPTO): 85 kg (187 lb)
First 10 Hours / 1 Month: Initial dealer inspection. Every 50 Hours / 3
Months: Check and clean the fuel filter and oil filter. Inspect spark
plugs, clean or replace as needed, and adjust gap to 0.9-1.0 mm
(0.035-0.039 in). Check and re-tighten all accessible bolts and nuts.
Apply grease to all sliding and rotating parts and grease nipples.
Every 100 Hours / 6 Months: Change gear oil, inspecting for water or
metal particles. Have a dealer check carburetor adjustment and ignition
timing. Inspect the water pump impeller for wear. Replace the water pump
impeller every 12 months.
General: Check anodes for corrosion and replace if significantly eroded.
Flush the cooling system with fresh water after each use in salt or
polluted water using the flushing attachment on the gear case.
Gear Oil Plug: 4 Nm (3 lb-ft)
Propeller Nut: 35 Nm (25 lb-ft)
Spark Plug: 27 Nm (20 lb-ft)
PTT Manual Relief Valve: 1.8 Nm (1.4 lb-ft)
The Tohatsu M50D2 is designed for a wide variety of small boats, where
its power-to-weight ratio and multiple configurations are advantageous.
Ideal applications include: Fishing Boats: A popular choice for small
aluminum tiller-steered boats, jon boats, and lightweight center
consoles.
Runabouts: Provides strong performance for small fiberglass runabouts
and bowriders. 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.
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