Choosing a power unit for a small vessel always starts with setting a budget and operating conditions. If you are looking for a reliable workhorse for planing under full load, but do not want to overpay for four-stroke technology, you should pay attention to time-tested solutions. Mikatsu has been supplying models to the market for many years that successfully compete with eminent brands due to affordable price and maintainability.
Model Mikatsu M40FES This is a classic 40 horsepower two-stroke engine, a middle ground for many owners of metal boats and large PVC membranes. The two-stroke cycle provides excellent low-speed traction and fast plane, which is critical for fishing or transporting cargo.
In this article, we will discuss in detail the design features powerplantWe'll look at the actual fuel consumption and discuss the nuances of maintenance, and understanding the working principles will help you avoid the typical mistakes in the first seasons of operation and extend the life of the unit.
Design features and power plant
The heart of the model Mikatsu M40FES It is a two-cylinder internal combustion engine with a carburetor system for feeding the mixture, and it is designed according to the "loop purge" scheme, which ensures efficient cleaning of the cylinders from exhaust gases and uniform distribution of the fuel and air mixture. The cylinder block is made of a special aluminum alloy, which has high thermal conductivity and resistance to corrosion in salt water.
The ignition system is particularly noteworthy, and it has a state-of-the-art Capacitor Discharge Ignition (CDI) system that doesn't require any adjustment to the candle gap during operation and provides a stable spark in all modes of operation, which solves one of the main problems of old contact systems, which is unstable starting in wet weather. High-voltage coils protected by sealed caps that exclude breakdown.
Technical nuances of the piston group
The Mikatsu M40FES pistons have three compression rings and one oil removable, a configuration that reduces oil carbon monoxide and increases compression, which is especially important for medium-power two-stroke engines. The gaps in the piston group are tailored to the thermal expansion of aluminum, so proper running is critical to maintaining tightness.
The cooling system is built on the principle of forced water circulation through an external pump. A pulse pump located at the bottom of the lower unit pump delivers off-shore water through channels in the cylinder block and exhaust system. The efficiency of heat removal is monitored visually by a control exit jet ("urinal"). If the jet is weak or intermittent, this is the first signal of a possible malfunction in the system. cooling.
Technical specifications and weight parameters
When choosing a motor, the key parameters are not only power, but also dimensions, weight, and gear ratio of the gearbox. Mikatsu M40FES The two-stroke scheme made the engine much lighter than four-stroke analogues of the same power, making it easier to transport and install on a transom.
Below is a detailed table with basic technical data that will help you compare the capabilities of the motor with the specifications of your boat.
| Parameter | Meaning | Unit of measurement |
|---|---|---|
| Workload | 698 | cm3 |
| Maximum power | 40 | hp |
| Weight (no fuel) | 72 | kilogram |
| Transfer ratio | 2.08 | - |
| Ignition system | CDI | - |
The important aspect is the control system. M40FES It is usually equipped with rumpling control, which makes it ideal for installation on boats where steering is not provided or impractical. However, the design allows the installation of remote control (D), which expands the range of applications. gas-reverse and the engine emergency stop button ("death button").
The weight of 72 kg makes this engine the limit for installation on light inflatable boats without reinforced transom, but ideal for keel PVC boats with a length of 4 meters and small metal boats.
Fuel consumption and efficiency of operation
The question of the economy of two-stroke engines is often controversial, unlike four-stroke engines, where the oil is in the crankcase, in the case of a cartridge, in the case of a cartridge. Mikatsu M40FES It uses a benzo-oil mixture, which means that some of the fuel is not completely burned and is released into the atmosphere along with the exhaust fumes, but modern Mikatsu carburetors allow you to minimize losses.
The actual fuel consumption depends on the mode of operation and the load on the propeller. At idling, the engine consumes the minimum amount of mixture, but the main flow occurs when entering the plane. Average figures indicate that at full gas the engine consumes about 12-14 liters of the mixture per hour. At cruising speed (about 70-80% of the maximum power), the flow is reduced to 8-10 liters.
- 🛢️ The ratio of the mixture: for breaking in is recommended 1:25, for normal operation - 1:50 (use high-quality oil for 2T engines).
- ⛽ Octane number: the manufacturer recommends the use of AI-92 or AI-95 gasoline, but always fresh, without alcohol content.
- 🌊 Conditions: Headwind and turbulence can increase fuel consumption by 15-20% due to increased hull resistance.
To improve efficiency, it is important to choose the right propeller. Too much will lead to a “failure” of revolutions and fuel overruns, and too little – to “twisting” the engine. The optimal mode is when the engine develops speeds in the range of 5000-5500 rpm at full gas.
breaking in process: step-by-step instructions
The break-in is the most important step in the life of a new engine, and it's in the first hours of operation that the piston rings, bearings and gears of the gearbox are laundered. Mikatsu M40FES This can lead to cylinder jacking and loss of warranty, and it takes about 10 hours to complete and requires your constant attention.
You start with idling, and for the first 10 to 15 minutes, the engine has to run at minimum speeds to warm up and lubricate all the knots, and then you can increase your speed for a short time, but not more than 50 percent of your maximum, and don't let it run at constant speed, you have to change the mode constantly.
☑️ Checklist of Mikatsu M40FES break-in
In the second and third watches, you can gradually increase the load, bringing the gas to 70-80%. It is important to monitor the engine temperature (touch through the casing, be careful) and the presence of a control jet of water. If you smell burning or hear a foreign knock, immediately turn off the engine. After the first 10 hours, you need to replace the engine. transmission oil in the gearbox, since it may appear products of primary grinding gears.
⚠️ Warning: Never run the engine in a barrel of water without an additional exhaust cooling system unless the exhaust design provides for it.
Maintenance and seasonal storage
Durability Mikatsu M40FES Two-stroke engines are less demanding to replace oil (because it is not in the crankcase), but more sensitive to the quality of the mixture and the condition of the cooling system. Regular washing of the engine with fresh water after each outing or on a salty pond is mandatory to prevent corrosion.
Every 50-100 hours, prevention is recommended, which includes checking and replacing spark plugs, cleaning the carburetor from possible deposits, and lubricating all lubrication points (suspension bearing, switching levers).
- 🔧 Candles: Check the clearance and color of the soda every 20 hours. Black soda indicates a re-enriched mixture.
- 💧 Cooling system: once a season, it is recommended to remove the pump cover and check the condition of the impeller for cracks.
- 🔩 Fastening: The vibration of the two-stroke motor is high, so once a year it is advisable to stretch all visible bolt connections.
In preparation for winter storage, the engine must be preserved, so you can extract the remaining fuel from the float chamber or add a special fuel stabilizer to the tank and let the engine run for 5 minutes, which will prevent the rubber seals of the carburetor from drying out and the formation of resinous deposits.
Keep the motor upright. If that's not possible, be sure to drain the oil from the gearbox and store the lower unit separately so that the oil glands don't deform under the weight of the oil.
Typical malfunctions and methods of their elimination
Even a reliable motor can require attention in operation. Mikatsu M40FES It's associated with a fuel system or ignition system, and being able to quickly diagnose a malfunction will save you time and money on evacuation, and the most common symptoms and their causes are listed below.
If the engine stalls at high speeds, the fuel supply system is most often to blame, it can be a clogged carburetor jetty, a polluted fuel filter or an air pump through the gasket, and it is also worth checking the ventilation of the tank - if it is clogged, a vacuum is created in the tank, and the gasoline stops coming in.
⚠️ Warning: If the engine overheats, don't pour cold water on the hot cylinder block. A sudden temperature drop can cause a crack in the metal. Let the engine cool naturally.
Lack of spark is the second most common problem. First of all, check the candle: twist it out, press the skirt to the mass of the engine and pull the starter. If there is no spark, check the coil and the stop switch on the tiller. Often the problem lies in the oxidized contacts of the high-voltage wire.
What to do if the compression is gone?
A sharp drop in compression in a two-stroke engine is often associated with the destruction of the crankshaft glands or the laying of the rings. You can use a compressometer for diagnostics. If the compression is below 6 atmospheres, the engine will not start well and lose power.
Frequently Asked Questions (FAQ)
What is the best oil to use for Mikatsu M40FES?
Use only high-quality mineral or semi-synthetic oils labeled TC-W3, designed for two-stroke outboard motors. Automotive oils are not suitable, as they form a lot of sodium and do not burn completely at low temperatures.
Can this motor be used for fishing?
Yeah, Mikatsu M40FES It has a corrosion-resistant coating that protects the main components from salt water, but after each outing, the motor must be thoroughly washed with fresh water to avoid the formation of salt deposits.
Which screw is better to put for a heavy boat?
For heavy boats or when fully loaded, it is recommended to use a screw with a smaller pitch (for example, 10 or 11 inches instead of the standard 12), which will allow the engine to more easily reach the speed and save the life of the piston group.
Why does the engine smoke when it's working?
Two-stroke engines always smoke more than four-stroke engines because of the burning of oil, but if the smoke has become blue and very thick, it may be the proportion of the mixture (too much oil) or the excess oil enters the combustion chamber through the glands.