Tohatsu M3.5B2 Specifications
| Engine Model: Tohatsu M3.5B2 3FO |
| Engine Type: 2-stroke 1-cylinder gasoline outboard engine |
| Total Displacement: 4.6 cu.in (74.5 cc) |
| Rated Engine Power: 3.5 Hp (2.6 kW) at 5300 rpm |
| Fuel System: Carburetor |
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The Tohatsu M3.5B2 is a technologically
uncomplicated yet highly effective outboard that distinguishes itself
through its lightweight and portable design. Its engineering focus is on
reliability and user convenience, highlighted by the loop-charged
induction system for smooth operation and fuel economy, and a CD
ignition system for quick and easy starts.
Users benefit from a simple tiller control with forward and neutral
gears, utilizing a 360-degree rotation for reverse thrust. The engine is
engineered for durability in marine environments, incorporating
high-grade marine aluminum alloy and zinc coating on internal water
passages for superior corrosion resistance, making it a reliable and
clean-operating powerplant for small boat applications.
Engine Model: Tohatsu M3.5B2
Engine Type: 2-stroke, single-cylinder, gasoline outboard engine
Number of Cylinders: 1
Displacement: 4.6 cu in (74.6 cc)
Cylinder Bore: 1.85 in (47.0 mm)
Piston Stroke: 1.69 in (43.0 mm)
Maximum Engine Power: 3.5 hp (2.6 kW)
Maximum Engine Speed: 4200-5300 rpm
Idle Speed: Data unavailable; specified by manufacturer.
Lubrication System: Pre-mixed fuel and oil
Exhaust System: Underwater exhaust
Cooling System: Forced water cooling
Ignition System: Flywheel magneto CDI (Capacitor Discharge Ignition)
Starting System: Manual recoil starter
Cylinder Bore Inside Diameter: 1.850-1.851 in (47.00-47.01 mm)
Piston to Cylinder Clearance: 0.0023-0.0035 in (0.06-0.09 mm)
Piston Ring End Gap: 0.007-0.013 in (0.18-0.33 mm)
Piston Ring Side Clearance: 0.0004-0.002 in (0.01-0.05 mm)
Piston to Piston Pin Clearance: 0.0002-0.0006 in (0.005-0.016 mm)
Connecting Rod Big End Side Clearance: 0.0051-0.0125 in (0.13-0.32 mm)
Fuel System Type: Carburetor
Fuel Pump Type: Integral
Fuel Type: Unleaded gasoline, 87 octane minimum
Fuel Tank Capacity: 1.47 qts (1.40 L) integral fuel tank
System Type: Pre-mix (fuel/oil ratio 50:1)
Engine Oil Type: Genuine two-stroke outboard oil, NMMA TCW-III certified
Engine Oil and Fuel Ratio: 50 parts unleaded gasoline to 1 part
two-stroke engine oil
System Type: Forced water cooling, thermostatically controlled
Water Pump: Driven by driveshaft, with rubber impeller
Flushing System: Flushing attachment available as an option for fresh
water flushing after use in salt or brackish water
| Mid Section and Lower Unit |
Mid Section: Integral driveshaft housing
Steering System: Tiller handle
Shift System: Dog clutch
Gear Shift: Forward - Neutral
Reverse: Achieved by rotating the entire motor 360 degrees
Gear Ratio: 2.15:1 (pinion 13, forward gear 28)
Gearcase Capacity: 0.19 qts (0.18 L)
Gear Lubricant Type: Genuine Tohatsu gear oil or API GL-5, SAE 80 to 90
weight
Trim System: Manual Trim and Tilt
Trim Positions: 4 positions
Maximum Tilt Angle: 70 degrees
Propeller Types: 3-blade
Propeller Diameter: 7.4 in (188 mm)
Propeller Pitch Range: 4.3 in (110 mm), 5.7 in (145 mm), 7.0 in (178 mm)
Propeller Material: Aluminum or plastic
Overall Length: 21.7 in (550 mm)
Overall Width: 8.7 in (220 mm)
Overall Height (Short Shaft model): 37.6 in (955 mm)
Overall Height (Long Shaft model): 42.6 in (1080 mm)
Transom Height (Short Shaft): 15 in (381 mm)
Transom Height (Long Shaft): 20 in (508 mm)
Outboard Weight (Short Shaft): 28.7 lbs (13.0 kg)
Outboard Weight (Long Shaft): 29.8 lbs (13.5 kg)
Engine Fuel: Unleaded gasoline, 87 octane minimum
Engine Oil: NMMA TCW-III certified two-stroke oil
Fuel/Oil Ratio: 50:1
Gear Lubricant: API GL-5, SAE 80 to 90
Gearcase Capacity: 0.19 qts (0.18 L)
Ignition Timing: 20 degrees BTDC
Spark Plug Type: NGK BP6HS-10 or NGK BPR6HS-10
Spark Plug Gap: 0.035-0.039 in (0.9-1.0 mm)
Every 50 Hours: Check spark plug,
check fuel line, clean fuel tank, check anodes, check gear oil level,
check propeller and shear pin, check starter rope for wear.
Every 100 Hours: Check cooling
system operation, check water pump, check/adjust carburetor.
Every 200 Hours: Replace gear oil,
replace spark plug.
Cylinder Head Bolt: 8.2 lb-ft (11 Nm)
Magneto Nut: 32.5 lb-ft (44 Nm)
Stern Bracket Nut: 11.5 lb-ft (15.5 Nm)
Emergency Stop Switch: 1.9 lb-ft (2.5 Nm)
Gear Oil Plug: 3.0 lb-ft (4 Nm)
Spark Plug: 20.0 lb-ft (27 Nm)
0The Tohatsu M3.5B2 is a versatile outboard ideally suited for a wide
range of small, portable watercraft. Its light weight and compact
dimensions make it an excellent choice for powering inflatable boats,
dinghies, and small tenders used as shore craft for larger vessels.
It is also a popular powerplant for small fishing boats, jon boats, and
canoes used on lochs, lakes, and rivers, where its portability allows
for easy transport and storage. The engine's straightforward design and
reliable operation make it well-matched for recreational boaters,
anglers, and as an auxiliary motor for sailboats, where efficiency and
ease of use are paramount.
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