Review of the outboard motor Tohatsu 3.5 hp: specifications and features

Choosing a reliable and light engine for a small inflatable boat is a task that requires a balanced approach. Tohatsu outboard motor 3 5 For many years, it has been one of the leaders in this market segment, attracting owners of floating craft with its light weight and proven design for years, and the Japanese engineering school has laid a huge margin of safety in this unit, making it relevant even decades after the first models were released.

Many anglers and hunters appreciate this model for its simplicity: there is little to break, and maintenance is within the power of even a beginner. Unlike the more complex four-stroke counterparts, the two-stroke scheme provides excellent traction at low revs. This is often the decisive factor when buying a fishing motor in overgrown water bodies or on rivers with strong currents.

In this article, we will discuss in detail all the technical nuances, configuration features and real-world experience of this popular unit. Tohatsu M3.5B It's still in demand, and how to maximize it, and let's look at the typical problems and the methods of solving them, so that your navigation always goes without surprises.

Technical specifications and design features

The basis of the reliability of this engine is its two-stroke design with one cylinder. the working volume is 49 cubic centimeters, which at a weight of only 9.8 kg provides power specification, sufficient for the confident movement of a boat up to 3 meters in length. Ignition system It is implemented via magdinos, which eliminates the need to connect the battery and makes the launch fully autonomous.

Cooling is done by off-shore water through the built-in pump, but at low speeds or when pulling the motor out of the water, it is critical to keep it from running "dry." lower unit's design allows you to adjust the angle of inclination, which helps to adapt the motor to different loading conditions of the boat. reverse-couplingwhich provides for the shifting of forward and reverse gears, as well as neutral.

The PVL or Mikuni carburetor (depending on the year of manufacture) is responsible for mixing. It's easy to maintain, but sensitive to fuel quality. Fuel tank It is usually a 1.2-liter set, which provides a range of about 3-4 hours of quiet movement, which is quite enough for fishing at a close distance from the shore.

⚠️ Warning: Never keep a full tank of gasoline engine indoors for more than a month, and the old fuel oxidizes and forms resins that can jam the carburetor's needle, making simple repairs a lengthy procedure.

To understand acceleration dynamics and speed specifications, it is worth looking at data that demonstrate the dependence of speed on load weight. Below is a table that reflects approximate speed figures for a hard bottom PVC boat.

Load weight (fisher + equipment)	Full speed (km/h)	Fuel consumption (l/hour)	Mode of work
Up to 80 kg	12-14 km/h	0.8 - 1.0 l/h	Full gas.
80-120 kg	10-12 km/h	1.1. 1.3 l/h	Full gas.
120-150 kg	8-10 km/h	1.4. - 1.6 l/h	Full gas.
Any weight	4-5 km/h	0.5 - 0.7 l/h	Economy move

The design of the propeller also deserves a special mention. The standard two-blade propeller is installed with a diameter of 7 inches in step 5. It does a great job of planing light boats, but on grassy bodies of water can often catch algae. Replacing with a three-blade version with a smaller step can improve traction, but reduce the maximum speed.

Advantages and disadvantages of the model

Analyzing the numerous feedback from owners, there are a number of undeniable advantages that have made this engine a classic of the genre: first of all, it is incredibly low noise level compared to Chinese counterparts of the same power, and vibration is also minimal, which reduces operator fatigue during long navigation.

The second major advantage is the availability of spare parts. Repair of outboard motors This series is set up in almost any service center, and the catalog numbers of the parts have not changed for years. Tohatsu 3.5 It is not difficult even in remote areas.

But it doesn't have to be idealized, it has its own downsides to be aware of before buying: a two-stroke engine requires a mixture of gasoline and oil, which is a inconvenience for some users, and environmental regulations are becoming stricter, and two-strokes are being pushed out of developed markets.

• ✅ Lightweight: even a fragile woman or teenager can carry the motor without the help of outsiders.
• ✅ Simplicity of design: the absence of complex electronics allows for repairs in the field.
• ❌ Fuel mixing: Keep in mind a 1:25 or 1:50 ratio depending on the type of oil.
• ❌ Smoke: at low speeds, the engine can noticeably smoke, which is not always pleasant for a fisherman sitting on the nose.

Another nuance is the lack of an emergency shutdown system of the engine (checks) on the oldest models, although in new versions. Emergency Stop Also, owners often complain about a tight handle of gas, which requires some addiction and periodic lubrication.

⚠️ Warning: When operating in salt water, be sure to wash the cooling system with fresh water after each exit. corrosion of aluminum alloys in seawater is very rapid and can cause the engine to fail in one season.

Service and preparation for the season

The durability of the unit depends on the quality and regularity of maintenance. Before the season, you need to conduct a visual inspection of the case for cracks and chips, special attention should be paid to the condition of the lower unit and anti-cavitation plate.

The first thing to do is to change the gearbox oil, and even if the engine is new, the factory oil is better drained after the first 10 hours, and then you put the engine vertically, twist the top and bottom gears, and let the gearbox run off, and then you pump the new transmission oil with a syringe before it comes out of the top hole.

The next phase is maintenance. carburetor If the engine was stuck with fuel for a long time, the membranes could coarse and the jelly clogs, it is recommended to remove the carburetor, wash it in an ultrasonic bath or a special cleaner and blow it with compressed air.

Ignition plugs are another important element. For two-stroke engines, candles with a potassium number specified in the instructions (usually NGK BR7HS) are suitable. The candle can tell you about the state of the engine: black and dry nagar indicates a rich mixture, white indicates a poor one, and oily - wear of the piston group.

Set up the carburetor and fix problems

The right setup of the carburetor is the key to the stable operation of the engine in all modes. PVLThe thrusters that are often found on these motors, there are usually two adjustment screws: a low-rev quality screw and a maximum speed limit screw. Factory setting is usually optimal, but can get lost over time.

To adjust the idle, you need to warm up the engine. The mix quality screw (located closer to the suction pipe) is screwed to the point, but without fanaticism, and then twisted to 1-1.5 turns. The engine must work steadily at minimum speeds and not deafen when the valve is sharply opened.

A common problem is that the engine doesn't hold up idle speeds or dies when you add gas, which may indicate that air is sucked through the crankshaft's coils or the gasket between the carburetor and the cylinder. To diagnose, you can spray WD-40 around the joints of the running motor, if the speed changes, then the tightness is broken.

• 🔧 If the engine develops low revs, check the exhaust window for overgrown with soot.
• 🔧 Engine trimming is often caused by water entering gasoline or a magdino malfunction.
• 🔧 Overheating can be a consequence of breakage of the impeller pump or clogging of water intake holes.

In some cases, the gap between the ignition coil and the flywheel must be adjusted strictly from 0.3 to 0.5 mm. Too much gap will lead to a weak spark, too little to damage the coil. To adjust, a special probe or sheet of paper of the desired thickness is used.

⚠️ Warning: Make sure to use a special skipper before removing the flywheel, and attempts to knock it down with a hammer or mount often cause the crankshaft to break, making repairs economically inexpedient.

The choice of the screw and the impact on speed

The standard propeller that comes with the kit is a trade-off between thrust and speed. But replacing the propeller is the easiest way to tune the engine. For heavy boats or fishing with more gear, it makes sense to put the propeller in a smaller pitch, which will make it easier for the engine to get on plane mode.

If you use a lightweight single boat and you want to have top speed, you can try a propeller with a larger pitch, but it's important not to overdo it: if the engine can't spin the propeller to a working turn (5000-5500 rpm), overheating and detonation will occur, which will quickly lead to a failure of the piston group.

How do you calculate the screw's pitch?

The theoretical speed depends on the pitch of the screw and the engine speed. Formula: V = (Step × Turn × 60) / (Transfer × 100,000). However, the real figures are always 15-20% lower due to the slip of the screw.

The screw material also plays a role. Aluminum screws are cheap and easy to recover, but when hitting a stone they bend, passing the blow to a lower unit. Steel or composite screws are more expensive, but they hold geometry better and often have a shock-absorbing sleeve protecting the gearbox.

When you choose, pay attention to the direction of rotation. Tohatsu 3.5 They have a standard left-hand rotation of the propeller (when viewed from the rear), and installing a propeller with the wrong direction of the blade will simply prevent the boat from sailing forward.

Storage and Conservation Recommendations

Proper storage in the off-season is 50 percent of the success of future operation, and if you're putting the engine away for the winter, the first thing you need to do is to get all the fuel out of the carburetor, you can shut off the fuel faucet and let the engine run until it stops, and the remaining gas will evaporate over the winter, leaving the resins that will clog the jellybars.

Then you have to replace the oil in the gearbox, even if it's changed recently, and the waste oil can contain wear products and microscopic metal particles that can corrosion the gears over the winter, and the new oil will create a protective film.

The motor needs to be kept upright, so that it prevents oil from leaking into the cylinder through the coils and deforming the lower unit under its own weight, and the ideal storage space is a dry, ventilated room with a constant temperature.

Remember to lubricate all the hinge joints and friction points with preservative lubricant, which is the gear shift, the rample and the fasteners, and this simple procedure protects the metal from corrosion and jamming.

Frequently Asked Questions (FAQ)

What is the best gasoline for Tohatsu 3.5?

The main requirement is freshness of fuel and no alcohol additives (ethanol can corrode the rubber elements of the carburetor of old models), gasoline should be mixed with oil in a ratio of 1:25 (for running) or 1:50 (for modern TC-W3) oils.

Why does the engine smoke at idle speed?

Smoke on idles is normal for a two-stroke engine, especially if the mixture is rich or the oil does not completely burn at low cylinder temperature. If the smoke is blue and caustic, perhaps too much oil gets into the combustion chamber due to the incorrect proportion of the mixture.

Can this motor be used on a boat 4 meters long?

Technically possible, but the efficiency will be low. Tohatsu 3.5 It is designed for boats up to 3-3.5 meters. On a four-meter boat, it will be able to bring it only to displacement mode (speed 5-7 km / h), there will be no talk of glising, and fuel consumption per unit of track will increase significantly.

How often should you change the oil in the gearbox?

The manufacturer recommends changing the oil in the gearbox every 100 hours or once a year before winter storage.

What do I do if the spark is gone?

First, check the candle by twisting it and applying it to the mass. If there is no spark, check the connection of the high-voltage wire and the condition of the cap. If everything is clean, it may have failed the magdino (ignition coil under the flywheel) or the wire inside the lower unit.