Choosing a small-to-medium-sized inflatable boat or light boat often comes down to balancing cost, reliability and availability of parts, with Southeast Asian brands leading the market with time-tested technology at affordable prices. Korean Mikatsu 9.9 outboard motorIt has been in stable demand for many years among fishermen and water lovers.
This model is a classic two-stroke engine, developed on the basis of proven Japanese drawings of the late 90s. Simplicity of design, lack of complex electronics and maintainability make it an ideal choice for remote regions and harsh operating conditions. Mikatsu M9.9BHS It is not just a means of transportation on water, but a working tool that requires the right approach to running and maintenance for long service.
Owners value this unit for its thrust and ability to run on different types of fuel, provided you are properly set up. However, like any equipment, it has its own features that you need to know about before buying. In this article, we will discuss in detail the specifications, nuances of operation and the secrets of tuning that will help you get the most out of your engine.
Technical specifications and design features
The 9.9 hp Mikatsu engine is equipped with a two-cylinder engine of 246 cubic centimeters. This configuration provides excellent balancing and reduces vibration levels compared to single-cylinder counterparts. A power of 9.9 horsepower is a kind of “gold standard” for boats ranging from 3 to 4.5 meters in length, allowing speeds of up to 30-35 km / h depending on load and type of hull.
An important design element is the CDI (Capacitor Discharge Ignition) ignition system, which guarantees stable spark formation even at low revs. carburetor The Japanese-made engine or its high-quality counterpart provides optimal mixing, which directly affects the efficiency and purity of the exhaust. The weight of the engine in the dry state is about 26-27 kilograms, making it easy enough to carry one person, but at the same time massive for sustainable operation on the transom.
The cooling system is forced, water-based, with water drawn through holes in the lower unit, a classic solution that works effectively in fresh and salt water, although the latter requires more thorough washing after use. A feature of the model is the ability to limit power to 5 hp by installing a special washer in the throttle valve.This allows the motor to be used with boats with power limitations or with unregistered craft in accordance with the legislation.
- 🚀 Engine type: two-stroke, 2 cylinders
- ⚓ Working capacity: 246 cm3
- 💨 Start system: Manual (traction starter)
- ⚙️ Transmission ratio: 2.08 (27:13)
Before first operation, be sure to check the oil level in the gearbox - often during transportation it may be drained or its level may be insufficient.
Advantages and disadvantages of the M9.9BHS
Analyzing the experience of thousands of owners, we can identify a number of objective advantages that have made this engine popular, first of all, it is high maintainability: the design is so simple that many malfunctions can be eliminated in the field with a minimum set of tools. Mikatsu parts are widely available and cost much less than for European or American brands.
On the other hand, there are disadvantages that you should know about in advance: a two-stroke lubrication system requires a constant presence of a special oil bottle at hand and careful mixing of the fuel mixture (or the use of a premix system if it is provided for by modification, although tank mixing is more often used), and the disadvantages include higher noise and vibration levels compared to modern four-stroke analogues.
⚠️ Attention: The use of pure gasoline without adding oil in a ratio of 1:50 (for running 1:25) will lead to instantaneous bullying of the piston group and engine failure, which is not a warranty case.
Another nuance is the quality of some attachments; the plastic of the casing may be less resistant to ultraviolet light than premium brands, and lower unit requires regular lubrication of the paddle shaft slits, but with proper care, these shortcomings do not affect the overall reliability of the power unit.
Proper breaking in: step-by-step instructions
The break-in process is a critical step in determining the life of the engine in the future. Neglect of the rules of running is the most common cause of early failures, the essence of the process is to grind the rubbing parts of the piston group and crankshaft bearings. break-in It should be carried out on an oil-rich mixture and at varying turns.
The first 10 motor hours (or 2 tanks of fuel) the engine should run on a mixture with an increased oil content. If the standard ratio is 1:50, then it is recommended to use 1:25 for running. Do not keep the throttle in one position for more than 2-3 minutes. Periodically give the gas, raising the speed to 70-80%, but do not go on full gas in the first hours of operation.
☑️ Checklist of Mikatsu 9.9 break-in
After the first tanks are developed, the mixture can be converted to a standard ratio of 1:50. It is important to monitor the engine temperature: if the water from the control hole does not flow or is running in a weak stream, immediately turn off the engine, this may indicate a break in the impeller water pump or clogging of the cooling system.
What to do if the engine smokes after running?
After switching to a mixture of 1:50, the smoke should decrease, but it can disappear completely only after 5-10 hours. If the smoke is black and caustic, check the quality of the oil and the correct proportion. Blue smoke after warming up may indicate wear of the gums, but in a new engine this is rare.
Setting up the carburetor and fuel system
The carburetor's performance is key to stable traction and efficiency. Mikatsu's factory setting is usually optimal for standard conditions, but when altitude, air temperature or fuel quality changes, adjustment may be required. The carburetor is equipped with two main adjustment screws: a mix quality screw (Low Speed) and a mix quantity screw (High Speed).
To start the setup, you need to warm the engine to operating temperature. The mix quality screw (usually marked as "L") is responsible for idling and transient modes. Write it to the point (not much!), and then twist it to 1-1.5 revolutions. The number screw ("H") regulates maximum speeds. Adjustment is performed by the test method: slightly changing the position of the screw, listen to the reaction of the engine.
| Parameter | Symptom of poor mix | Symptom of rich mixture | Action. |
|---|---|---|---|
| Idle move | It's dead when you dump gas. | Unstable turnovers, black smoke | Turn the L screw. |
| Dispersal | "Failure" at sharp gas | Clapping to the muffler | Correct the L screw |
| Max, speed. | The engine is not developing. | Black gar on a candle, high consumption | Turn the screw H |
When adjusting the maximum speed, be careful: too poor a mixture at high speeds can lead to overheating and burnout of the piston. If you are not sure about your actions, you should leave the factory settings or consult a specialist. Also remember to change the fuel filters, since dirt in gasoline is the main enemy of the carburetor.
⚠️ Warning: After seasonal storage, be sure to drain the fuel residue from the carburetor through the drainage hole, otherwise the gasoline will evaporate, leaving resins that will clog the jellyfish.
Fuel consumption and efficiency of operation
The two-stroke Mikatsu 9.9 hp consumes an average of 3 to 4 liters of fuel per hour when driving at half-strength (cruising speed). At full gas, the flow can reach 5-5.5 liters per hour, these figures are averaged and depend heavily on the propeller, loading of the boat and the state of the bottom.
By comparison, four-strokes can be 20-30% more economical, but they are significantly heavier and more expensive to maintain. Mikatsu's economy is achieved by choosing the right propeller. If the propeller has too much pitch, the engine will run in tension without developing revs, which will lead to overspend and overheating.
Optimal fuel consumption is achieved when the engine is operating in the range of 70-80% of the maximum power, when the boat has already gone to planing, but the engine does not work at the limit.
The use of quality oil also impacts the economy: Good synthetic oil burns cleaner and allows lesser decogging of candles and exhaust tracts, which indirectly retains power and reduces fuel consumption in the long run.
Frequent malfunctions and methods of their elimination
Despite reliability, typical problems can occur in operation, most often owners face startup difficulties or unstable idling, 80% of the time the cause is spark plugs or fuel mix quality. Candles. You should twist and check the color of the coke every 50 hours.
If the engine has lost traction, check the condition of the lower unit. Often the shaft is wound with algae or line, which creates resistance and can damage the osteoils. It is also worth checking the compression: for a serviceable Mikatsu 9.9, it should be at least 8-9 atmospheres. A compression drop below 6 atmospheres indicates the need for major repairs of the piston group.
- 🔥 Problem: The engine is dead on idle cars. Solution: Clean the carburetor, check the air suction.
- 💧 Problem: No water in the control trickle. Solution: Replace the impeller pump, clear the thermostat.
- 🔊 Problem: Foreign knock. Solution: Check the crankshaft and rod bearings.
If you do not have experience, it is better to entrust this work to the service center.
How often should you change the oil in the gearbox?
Replace the oil in the gearbox is recommended once a season or every 100 motor hours. Before draining the old oil, warm up the engine to make the oil more fluid. The color of the oil should be clear or slightly yellowish. If the oil is of the color "coffee with milk" - this is a sign of water entering, which requires replacing the oil oil oils.
Can I use Mikatsu 9.9 for sea fishing?
Yes, but with limitations, the engine has a corrosion-resistant coating, but it's not designed to be in an aggressive salty environment, and after each outing, you need to thoroughly wash the engine with fresh water, especially lower unit and cooling systems, and you should use a spray preservative to protect the outside surfaces.
Which octane of gasoline is best used?
The manufacturer recommends the use of gasoline AI-92 or AI-95. the use of gasoline with a lower octane number can lead to detonation and damage to the piston group. Gasoline should be fresh, because with prolonged storage (more than 3 months) it loses its properties and forms resinous deposits.