Choosing a suspended boat-engine For a small inflatable boat or a lightweight aluminum boat, it often comes down to finding a balance between power, weight and reliability. In the entry-level segment, where 5 horsepower units rule the ball, the Japanese brand is a brand of the first-generation model. Tohatsu It has been a leader for decades, and its four-stroke models have become the benchmark of reliability for fishermen and lovers of relaxing on the water.
Why is it that four-stroke design is so exciting for water-powered motorists? It's all about sustainability, efficiency and low noise. Internal combustion engine With a full four-stroke cycle (intake, compression, stroke, exhaust) it is much softer than its two-stroke counterparts, which is critical when you are in the confined space of a small PVC boat, where the smell of exhaust gases and vibration can ruin all rest.
In this article, we will discuss in detail the technical features of the model Tohatsu MFS5C You'll learn about the nuances. maintenanceWe're going to focus on real-world usage instead of using formulaic phrases, and how to extend the life of your "Japanese" for years to come.
Technical specifications and design features
The heart of the model MFS5C It is a single cylinder engine with an overhead valve arrangement (OHV), which allows for high fuel efficiency and excellent low-speed thrust. The cylinder capacity is 83 cubic centimeters, which is the optimal value for the declared power. cooling Here it is water, forced, which guarantees a stable temperature even with prolonged operation at full gas.
The dry weight of the unit is about 25 kilograms, and for a four-stroke design, this is a very good figure, although it is heavier than two-stroke counterparts. centre The four-strokes are lower, which has a positive effect on the stability of the boat. The transom plate is made of a strong aluminum alloy, resistant to corrosion in salt water.
The CDI (Capacitor Discharge Ignition) ignition system deserves special attention, and it doesn't require an external battery to start, because the power is generated by the built-in magneto, which makes the motor fully autonomous. neutrality with a screw lock, which simplifies the start and warm-up of the engine in the parking lot.
Hidden feature of the design
Unlike many Chinese analogues, the Tohatsu MFS5C uses forced valve lubrication through the skewer, which significantly reduces the wear of the gas distribution mechanism at high revs.
Below is a table of the main technical parameters for quick assessment of your requirements:
| Parameter | Meaning |
|---|---|
| Type of engine | four-stroke, OHV, 1 cylinder |
| Workload | 83.2 cubic centimetre |
| Maximum power | 5.0 hp (3.7 kW) at 5,500 rpm |
| Launching system | Manual starter |
| Weight (dry) | 25.0 kg |
Advantages of the Tohatsu four-stroke scheme
The main trump card of four-stroke engines Tohatsu The fuel consumption of a 5 hp model is about 1.1 to 1.3 liters per hour at full speeds. At a cruising speed that is usually about 70-80% of the maximum, consumption drops to a minimum. For comparison, a two-stroke engine of similar power will eat 30-40% more gasoline at the same load.
The second important aspect is eco-friendliness. The four-stroke crankcase doesn't have oil, it's in a separate container (the crankcase) and it circulates through the lubrication system, and the combustion chamber only gets cleaner fuel, which means that the exhaust gases are cleaner, and the water around your boat is not covered by rainbow oil film, which is especially true for water bodies with strict environmental controls.
- 🌊 Low noise and vibration make fishing more comfortable.
- ⛽ No need to mix gasoline with oil before refueling.
- 🔧 The engine resource before the first overhaul is much higher than that of two-stroke analogues.
However, it is worth remembering the design features. Four-stroke engine You can't transport it on your side or upside down without first draining the oil, because it can get into the combustion chamber or air filter, and this requires more discipline in the owner's preparation for the water.
Fuel, oil and preparation for work
For a stable job. Tohatsu MFS5C Requires gasoline with an octane rating of at least 92 (research method) or 87 (motor) fuels of lower quality can lead to detonation, overheating and failure of the piston group. Gasoline must be fresh; storage of fuel in the tank for more than one month is not recommended, as modern additives lose their properties, and a resinous plaque is formed.
Unlike two-strokes, it uses pure gasoline. The oil is poured separately into the engine crankcase. The manufacturer recommends using API mineral or semi-synthetic oils of SG, SH, SJ, SL or SM with a SAE 10W-30 or 10W-40 viscosity. The oil volume in the crankcase is only 0.35 liters. It is important to check the level regularly through the cartridge. oil-probe.
⚠️ Warning: Never start an engine without oil or below the minimum mark, which will result in instant bullying and overhaul.
Before you start, you need to put the motor on a transom, you need to put the rods in, you need to put the lower unit in the water. Open the fuel crane, press the fuel pump pear several times until it's solid. Then pull the starter handle to the stop to get the decompressor on, and you make a sharp jerk.
☑️ First engine start
Maintenance regulations
Japanese equipment is famous for its reliability, but only if the regulations are followed. maintenanceFor Tohatsu 5bhp There are clearly defined intervals for replacement of consumables, and ignoring these rules is the most common cause of breakdowns that are not recognized as warranty.
The first maintenance is usually done after the first 10 hours (or a month of operation) are produced, during which time the parts are grinded, and metal shavings may appear in the oil. Therefore, the first oil change is mandatory. Subsequent replacements are made every 50-100 hours or once a season, depending on the intensity of use.
- 🔩 Replacement of motor oil: every 50 motor hours or once a year.
- 🕯️ Ignition plug replacement: every 100 hours (use NGK BR6HS or analogues).
- 💧 Washing of the cooling system: as needed if the motor was running in dirty water.
It is also important to check the condition. fuel-filterIt's located inside the carburetor float chamber, and if the engine starts to stall at high speeds or twitch, it's probably clogged with dirt or water, and it's easy to extract and wash in gasoline.
After each operation in salt water, be sure to rinse the outside of the motor with fresh water. Do not direct a strong jet of water under pressure directly to the dust ducts of lower unit and electric connectors.
Typical malfunctions and methods of their elimination
Even the most reliable boat-engine It can be a problem, most of the time, the owners. Tohatsu 5bhp If the engine doesn't start, first check for a spark. Twisted the candle, press it with a skirt against the metal part of the engine (mass) and pull the starter. The spark should be bright blue. If there is no spark, check the connection of the high-voltage wire and the state of the ignition coil.
The second common problem is the lack of fuel supply, which can be caused by clogging of the carburetor's jellyplates, especially if the engine has been stuck with gasoline for a long time, and often the vent in the fuel tank lid gets clogged, creating a vacuum. Unscrew the tank lid and try to start the engine again.
If the engine is running but is warming or there is no water coming from the control hole, immediately turn it off! impeller (water pump impeller) or water intake clogging, and without cooling, it will destroy the piston in minutes.
⚠️ Warning: If the engine is Troit (unstable), don't try to get to the base on full gas. This can cause the piston to burn out.
The secret of setting up the carburetor
In the factory, Tohatsu carburetors are perfectly tuned. Don't twist the screws of quality and quantity of the mixture without having a gas analyzer and experience. Most often, the problem is not the settings, but the air pump through the intake manifold.
Comparison with competitors and final choice
In the market of 5-horsepower engines Tohatsu There are serious competitors, such as Yamaha, Honda and SuzukiThe Honda 5hp is often praised for even quieter work, but it usually costs more and is more difficult to maintain due to its unique design. The Yamaha 5hp is a direct analog, often assembled in the same factories, but with a different logo and a slightly higher price tag.
Tohatsu It offers the best value for money, and parts are available, the design is simple and easy for any mechanic, and many boat manufacturers (e.g., the boats are not the only ones that can be used). Nissan Marine In the past, Tohatsu engines were used, which indicates a high level of trust in the brand.
When choosing between a two-stroke and a new four-stroke TohatsuWe definitely recommend a new four-stroke, and the difference in comfort, fuel consumption and smoke-free will cover the difference in price for one or two seasons of active use.
The Tohatsu MFS5C is a small boat workhorse that can last 10 years without any major investment if oil is changed in a timely manner.
In conclusion, Tohatsu outboard motor 5 hp four-stroke It is a mature, technically advanced solution for boats up to 3.5 meters long, easy to operate, economical and reliable, and simple rules of operation allow you to enjoy water trips without being distracted by technical problems.
Can I fill Tohatsu 5 hp with AI-95 gasoline?
Yes, it can. The engine is adapted to run on gasoline with an octane number of 92 and above. The use of AI-95 is even preferable, since modern fuels with a higher octane number often contain better packs of detergent additives, which is useful for a carburetor.
How often should you change the oil in the gearbox?
The gearbox oil changes less frequently than the engine oil, about once every 200 hours or every two seasons, but it needs to be checked annually: if the oil is milky, then the sealing of the omentums is broken and water is in the gearbox.
Why does the engine stop at idle speed?
The most likely cause is contamination of the idle jeckler carburetor or the sucking of unaccounted air through the gasket of the intake manifold, and it is also worth checking the gap of the spark plug, which should be 0.7-0.8 mm.
Should the engine be allowed to rest?
four-stroke engines Tohatsu They have a forced lubrication and cooling system that allows them to work for long periods without interruption, but if you go on a long trip on full gas against strong winds, sometimes it is useful to drop the gas for a couple of minutes to reduce the heat load.