Choosing a reliable power plant for an inflatable or metal floater is often a challenge, especially when the budget is tight and the requirements for traction are high. two-stroke Tohatsu is a leading brand, offering excellent value for money, and the 18-horsepower model is traditionally considered the middle ground for boats ranging in length from 3.5 to 4.5 meters.
This unit attracts the attention of water engines for its simplicity of design and time-tested reliability. Unlike more complex four-stroke counterparts, it is easier to maintain and requires less space to transport. Tohatsu M18B2 as the main option for fishing and resting on the water.
In this article, we will discuss in detail the technical specifications, features of operation and the real capabilities of this engine to help you make an informed decision.
Technical specifications and design features
At the heart of this model is the classic two-cylinder unit, which delivers excellent low-speed traction, with a displacement of 246 cubic centimeters, which allows you to push the boat efficiently even when fully loaded. The important parameter is weight: just 36 kilograms make this engine one of the lightest in its class, which is critical for carrying alone.
The ignition system is built on CDI (Capacitor Discharge Ignition), which guarantees stable sparking in all weather. The Mikuni carburetor installed in the factory is known for its unpretentiousness to fuel quality, although the use of fresh gasoline always prolongs the life of the engine.
The secret to high traction
Why is 18 hp better than 15?: Many people don’t know that the 18-power model has a modified carburetor and exhaust settings compared to the 15-horsepower version. This gives a thrust gain on planing up to 15%, which is critical for heavy boats.
And it's worth noting that there's a forced lubrication system that mixes the oil with the fuel automatically, so you don't have to pre-cook the mixture in a canister, you just put the oil in a special tank, which makes it easier to refuel and reduces the risk of misproportion, which is often the case with beginners.
- 🚀 Power: 18 hp at 5000 rpm provides a confident exit to planing.
- ⚖️ Weight: 36 kg in full configuration (excluding fuel and oil).
- 🌊 lower unit: Short (S) and long (L) leg options are available for different types of boats.
- 🔧 Transmission: The gear ratio 2.08 (27:13) is optimized for the propeller's emphasis.
Dynamics and speed indicators on the water
The actual performance of the engine depends on the type of boat, load and the chosen propeller. On a light inflatable boat with one passenger, this "Japanese" is able to accelerate the boat to 30-32 km / h. However, if you plan to ride with a company of three or four people, the speed will drop, but the thrust will remain sufficient for confident movement.
For metal boats like Crimea or Kazanka, 18 forces can be the limit. In such cases, it is important to choose the right pitch of the screw. A standard screw is often too light to allow the engine to turn around, or too heavy to enter mode. Experiments with screws are a mandatory part of the setup.
It's important to understand that a two-stroke structure takes time to warm up, and in the first 5-10 minutes, you don't have to give full gas, especially in cold weather, and this will allow the piston group to warm up evenly, avoiding hitters and jamming, and after warming up, the motor responds to the gas handle instantly.
⚠️ Attention: Do not try to open the throttle sharply on a cold engine. A sharp jump in speed can lead to the pumping of excess air and the impoverishment of the mixture, which is dangerous for the piston group.
Fuel consumption and efficiency of operation
The question of appetite of the engine is always acute, especially at long crossings. Tohatsu 18 It consumes an average of about 5-6 liters of fuel mixture per hour at full speeds. At a cruising speed of about 70-80% of the maximum, the flow rate decreases to 3-4 liters.
The ratio of oil to gasoline mixing is 1:50 for modern TC-W3 oils, which means that 20 liters of AI-92 or AI-95 gasoline require only 400 milliliters of oil.
To calculate the budget of the trip, it is worth considering that the tank with a volume of 24 liters (standard for many models) will allow you to spend about 4-5 hours on the water in active planing mode.
Use a fuel-sludge filter in front of a carburetor, which costs a penny, but saves the jellyclera from getting garbage from the tank, which is a common cause of unstable work.
Maintenance and maintenance
Regular maintenance is the key to a long life of your engine. The basic procedures are simple and accessible to any owner. The first thing you need to do is monitor the state of the spark plug. On two-strokes, it works in a more aggressive environment, so it needs to be replaced or cleaned more often than on four-strokes.
The lubrication of the gearbox requires attention at least once a season or every 100 motor hours. The oil in the gearbox changes color if water gets there, which signals the need to replace the ossels. It is also important to periodically lubricate the rotating points of the rumble and throttle control.
☑️ Seasonal engine maintenance
Special attention should be paid to the cooling system. Check the control stream of water regularly. If it becomes weak or disappears, immediately turn off the engine. Working without cooling leads to overheating and deformation of the cylinder head in a matter of minutes.
| Procedure | Frequency | Materials required |
|---|---|---|
| Candle replacement | Every 50 m/h | Candle NGK BR7HS |
| Lubrication of the gearbox | 1 time in season | Transmission oil |
| Cleaning the carburettor | If necessary, | Carburettor cleaner |
| Replacement of the fuel filter | Every 100 m/h | Sludge filter |
Comparison with competitors and modifications
In the outboard motor market, Tohatsu M18B2 There are direct competitors, such as the Yamaha 15CMHS or Suzuki DF15. However, the Japanese brand often benefits from a richer configuration and the availability of an electric starter in some versions (although the 18th model often comes with a manual start).
There are some remote-controlled modifications, which are rare for this kind of power, which allows you to put the motor on a boat where the rample control is uncomfortable because of the tightness of the cockpit, and it's also worth mentioning the shortened lower unit version, which was designed specifically for shallow water.
The Tohatsu 18’s main advantage over its competitors is the combination of a minimum weight (36 kg) and an automatic oil mixing system, which is rare in this class.
When choosing between a used engine and a new one, it is important to consider the resource. Tohatsu two-stroke engines run for a very long time, but the condition of the piston group is better checked with a compressometer. The presence of spark and compression above 8 atmospheres indicates that the engine will still serve.
⚠️ Attention: When buying a used motor, be sure to ask the seller to start it. The absence of smoke from the exhaust (except for short-term at start-up) and smooth sound of work are signs of serviceability.
Frequently Asked Questions (FAQ)
What is the best gasoline for Tohatsu 18?
It is recommended to use AI-92 or AI-95 gasoline with an octane number not lower than the stated in the instructions. The main requirement is freshness of the fuel. Gasoline that has been in the tank for more than 2-3 months loses its properties and can coke the carburetor.
Can this motor be used in salt water?
Yes, Tohatsu engines are corrosion-resistant and are made of salt-water-resistant materials, but after each landing in the sea, you must thoroughly wash the engine with fresh water to avoid crystallizing salt in the cooling system.
How to properly preserve the engine for the winter?
You need to fully develop fuel from the carburetor (let work until the stop), remove oil from the gearbox and pour new, as well as treat the internal cavities of the cylinders with conservation oil through the candle hole.
Why does the engine stop at idle speed?
The most common cause is idle jellier contamination or air suction through the carburetor gasket, and it is also worth checking the fuel level in the float chamber and the condition of the spark plug.
In conclusion, Tohatsu 18 It remains one of the most rational choices for small boat owners, and has been tested for decades, and its simplicity of design allows for repairs even in the field, and if maintained properly, it will be a reliable assistant for years to come.