Choosing an outboard motor for a lightweight inflatable boat or a small boat often becomes a difficult dilemma, where you have to balance power, weight and price. Tohatsu M3 5b2s outboard motor It has proven itself to be a benchmark for reliability and simplicity, and has been in steady demand for fishermen and leisure travelers for many years, thanks to its time-tested design.
Unlike more complex four-stroke analogues, this unit is a classic two-stroke This solution allows you to significantly reduce the weight of the entire device, which is critical when you're transporting it on the roof of a car or carrying it by hand to water. lowweight The lack of sophisticated electronics makes this model ideal for quiet fishing and short exits.
In this article, we will discuss the technical details, service features and real-world capabilities of this engine, you will learn how to prepare the fuel mixture correctly, what to look for in the first operation and why this engine is often called “unkillable”.
Technical specifications and design features
The basis of model reliability Tohatsu M3.5B2S The engine develops a power of 3.5 horsepower, which formally allows it to be operated without registration in the GIMS (subject to the conditions for the length of the vessel and the total power), the working volume is 49 cubic centimeters, and the maximum revolutions reach 4500-5500 rpm depending on the load and setting.
⚠️ Note: Despite air cooling, it is not recommended (long-term) to work at full speeds without loading or with a blocked water intake, as this can lead to overheating and deformation of the piston.
The dry engine weighs just 9.8kg, making it one of the lightest in its class. The ignition system here is electronic (CDI), which eliminates the need to replace candles too often and provides a stable spark even in wet weather. float-float It is easy to adjust and resistant to fuel quality.
The design of the lower unit is designed to protect against impact, and if you hit an underwater obstacle, the motor can recline, keeping the integrity of the lower unit pipe intact. fold-out requires a check before each exit so that it does not jam at the wrong time.
The combination of weight less than 10 kg and power of 3.5 hp makes this model optimal for boats up to 3 meters long with a carrying capacity of up to 200 kg.
It is important to note that there is a built-in fuel tank of 0.9 liters, which is enough for about 1.5-2 hours of economical operation. For many anglers, the absence of the need to carry an external canister is a decisive factor when choosing this particular modification.
Advantages of a two-stroke lubrication system
A key feature that is emphasized by the labeling 2S The name of the model is, you know, you have to make a fuel mix. Two-stroke engines don't have a separate crankcase lubrication system, so the oil is mixed directly with the gasoline, and this provides lubrication for all the rubbing parts: the piston, the cylinder and the crankshaft.
Use of quality two-stroke oil Japanese engineers recommend using oils with a tolerance of TC-W3. The mixing ratio is usually 1:50 (20 ml of oil per 1 liter of gasoline) for running and 1:100 (10 ml per 1 liter) for constant use, but always check the instructions on the oil packaging.
- 🛢️ Simplicity of design: The absence of an oil pump and crankcase reduces the number of parts that can fail.
- 🚀 High specific power: The two-stroke cycle allows you to remove more power per unit volume compared to the four-stroke counterparts.
- 💰 Service availability: Repairing a piston group or replacing glands is cheaper and requires fewer tools.
Some owners mistakenly believe that you can pour oil “on the eye”. Accurate adherence to the ratio of 1:50 during break-in is a prerequisite for the formation of the correct oil wedge on the walls of the cylinder. Violation of this rule in the first hours of operation can lead to bullies that can no longer be corrected by grinding.
Modern synthetic oils have made a lot of improvements in environmental friendliness and reduced exhaust smoke. Tohatsu M3.5B2S with high-quality synthetic oil, the smoke from the exhaust will be almost invisible, and the candle will not form black soda.
Instructions for start-up and primary break-in
Proper running is the foundation of your engine life, and many beginners ignore this stage, relying on "Japanese quality," but it is the first 10 motorcycle hours that determine how long it will last. Tohatsu M3 5b2s outboard motorThe process of grinding parts requires work on an enriched mixture and variable loads.
First, you need to prepare a fresh fuel mixture. Gasoline should be at least AI-92, preferably AI-95, without alcohol (ethanol can destroy rubber seals of the carburetor).
☑️ Checklist before first launch
The launch process is carried out as follows:
1. Translate the pen Start/Stop position START.
2. Open the fuel faucet (if there is a valve) or make sure that the tank cover has an air hole.
3. Push the fuel pump button (primer) 5-7 times until the air bubbles disappear in the transparent tubes.
4. Pull the starter's handle with a sharp but not overly strong jerk.
⚠️ Warning: Never start the engine out of the water (on land) even for a few seconds. The lack of water cooling will instantly overheat the pump and deform the exhaust system.
The break-in mode lasts about 2-3 tanks of fuel. At this time, do not open the throttle more than 50%. Periodically change the speed: work on idles, then add the gas, reduce again. This allows the piston rings to fit evenly to the walls of the cylinder. After the first tanks are developed, it is recommended to replace the spark plug, as it may settle excess oil.
Table of fuel mixture preparation and consumption
One of the most common questions owners have is to accurately calculate the proportions: an oil dosage error can cost the engine its life. Below is a reference table for mixing gasoline and oil depending on the tank volume.
| Volume of petrol (litres) | breaking in oil (1:50), ml | Oil for work (1:100), ml | Mode of work |
|---|---|---|---|
| 1.0 | 20 | 10 | Normal/Economic |
| 3.0 | 60 | 30 | Long fishing |
| 5.0 | 100 | 50 | A day's supply. |
| 10.0 | 200 | 100 | Preparation for the season |
Fuel consumption of the model M3.5B2S It's about 1.2 to 1.5 liters per hour at full speed. At trolling speed (about 2000 rpm), consumption drops to 0.6 to 0.8 liters. Built-in tank capacity of 0.9 liters is enough for about 40 to 50 minutes of active work at full thrust or for 1.5 hours in quiet mode.
It is not recommended to store the finished mixture for more than one month. Gasoline is oxidized and oil precipitates, which leads to the formation of resins in the carburetor. If you plan to take a break from operation for more than 2 weeks, it is better to develop the residue of fuel from the tank or drain them.
Use a measuring syringe or a special oil dispenser to make sure you don't make a mistake in proportions. It's almost impossible to pour 20 ml per 1 liter of gasoline into the eye without experience.
Adjusting the carburetor and setting up the idle
Factory setting of the carburetor Tohatsu M3 5b2s outboard motor However, the change of season, altitude or fuel quality may require intervention. The carburetor usually has mix quality screws and idling speeds.
If the engine stalls when the valve is opened abruptly or is not operating stable on idles, adjustment may be required. The mix quality screw (usually designated as L or H, or just one screw on simple models) allows you to enrich or impoverish the mixture. Wripping the screw impoverishes the mixture, twisting - enriches.
Procedure for setting up:
1. Warm up the engine for 5-10 minutes.
2. Set the idle screw so that the motor is stable.
3. Smoothly turn the screw of the quality of the mixture, achieving maximum speed.
4. Adjust the idle screw to the desired values.
The Secret to Stable Work
Often the problem is not the settings, but the state of the fuel filter-grid inside the tank. If it is filled with garbage or oxides, no adjustment of the screws will not help - the engine will "choke" at high revs.
It's worth remembering that carburetor Excessive depletion of the mixture (too little oil/gasoline) leads to overheating and burnout of the piston, and excessive enrichment leads to loss of power and throwing of the candle. If you are not sure of your actions, you should consult a specialist.
Maintenance and storage in winter
The durability of the motor is directly dependent on the regularity of maintenance, the basic service includes visual inspection, candle check, lubrication of rotation points and cleaning of algae after each operation in salt water. Tohatsu M3 5b2s outboard motor You need to wash thoroughly with fresh water.
The spark plug should be twisted and checked every 50 hours, and the color of the insulator will tell you about the engine:
Brick-brown color: ideal mode of operation.
Black velvety soda: a rich mixture or excess oil.
White or melted insulator: poor mixture, overheating or improper ignition.
Preparing for winter storage requires a special approach: you can not leave the engine with fuel in the carburetor for a long time, because the light fractions of gasoline will evaporate, and there will be resins that clog the jellybers, you either need to develop the fuel to stop or completely drain it.
- 🔧 Lubricate all hinge joints and cables with silicone lubrication to protect against corrosion.
• 🛡️ Treat the outer metal surfaces with an anti-corrosion spray.
• 📦 Keep the motor in a vertical position in a dry room, covering it from dust.
⚠️ Warning: When stored upright, make sure that the lower unit glass is completely water, otherwise, when frozen, it can break the pump or pipe body.
Frequently Asked Questions (FAQ)
Can I use it? Tohatsu M3.5B2S In salt water?
Yes, the motor has corrosion protection, but after each release into salt water, it must be washed with fresh water and lubricated moving parts, and ignoring this rule will lead to a rapid failure of the pump and fasteners.
Which gasoline is better to pour: AI-92 or AI-95?
The manufacturer allows the use of AI-92, but the AI-95 with a higher octane number provides more stable operation and is less prone to detonation.
Why does the engine smoke blue smoke?
Blue smoke is burning oil. On a new engine, it's normal during break-in. If the old engine is smoking, you may have broken the proportion of the mixture (too much oil) or oil that is not designed to be water-cooled (not TC-W3).
Do I need to register this motor in GIMS?
According to the current legislation of the Russian Federation, engines with a capacity of up to 10 hp (inclusive) do not require registration if the total weight of the equipped vessel with an engine does not exceed 200 kg. Tohatsu M3 5b2s outboard motor The boat has a power of 3.5 hp, it falls into the category of unregistered, provided that the boat is matched by weight.