Choosing a power unit for a small vessel is always a trade-off between power, weight and cost. The 9.8 horsepower is one of the most popular outboard motors in the class, as it allows you to achieve decent speed while remaining within the budget category. It is this power indicator that often becomes borderline for non-authorized control in some jurisdictions, which makes such engines especially attractive for fans of fishing and water recreation.
The modern market offers a huge variety of models from Chinese, Japanese, American and European manufacturers. Two-stroke and four-stroke Modifications have unique features that directly affect the choice of the end user, and understanding these differences is critical to buying a product that will last for years.
In this review, we will analyze the technical nuances in detail, give an up-to-date rating of manufacturers and help you determine the optimal model for your PVC boat or metal hull. A properly selected power plant is a guarantee of safety and pleasure from each foray into the reservoir.
Key criteria for choosing a 9.8 hp engine
The first and most important parameter to look at is the type of engine cycle. Two-stroke engines (2T) is traditionally lighter than its four-stroke counterparts, a critical factor for lightweight inflatable boats, and is easier to transport because it can be carried in any position without requiring a strictly vertical installation in the trunk of the car.
However, four-stroke (4Ts) are more efficient and environmentally friendly, consume less fuel per kilometer and operate much quieter, which is highly valued by fishermen, and have a higher lifespan for a four-stroke engine, provided that oil is changed on time and maintenance is followed.
Motor weight is the second most important factor. For inflatable vessels with plywood or aluminum transom, every extra kilogram is palpable. If you plan to often pull the boat ashore or drag it over obstacles, then the models with a lightweight design should be preferred. At the same time, the heavier engine provides better centering of the boat and stability on the wave.
- 🚤 Fuel type: The choice between pure gasoline (2T with oil) and AI-92/95 (4T).
- ⚖️ Mass: Two-strokes weigh from 20 kg, four-strokes - from 25-27 kg.
- 🔊 Noise: The 4Ts are quieter, which is important for trolling and night fishing.
⚠️ Attention: When buying a two-stroke engine, be sure to consider the need to mix gasoline with oil in the right proportion. Working on clean gasoline will instantly disable the piston group.
Overview of popular brands and models
The Japanese company has been the market leader for many years. TohatsuTheir MFS (four-stroke) and MD (two-stroke) models are considered the benchmark of reliability. Tohatsu 9.8B They are equipped with a CDI system, which ensures stable launch even after long downtime. Many other brands, including some Mercury models, are actually re-laid Tohatsu, manufactured in the same factories.
Chinese manufacturers, such as Hidea, Parsun and Sea-ProIn recent years, we've made a huge leap in quality. Hidea HD-F9.8FHS They're copying the design of Japanese models, offering similar specifications at a lower price, and it's important to understand that different names can hide engines from the same conveyor, so you should look at the manufacturer, not just the brand nameplate.
American giant Mercury The FourStroke 9.9/15 series offers the option of software or mechanical reconfiguration of the throttle to increase power to 15 hp, making them an excellent choice for those who want to have a power reserve "for growth" or for use with heavier boats.
The secret of power conversion
Many 9.8 hp engines are structurally 15-horsepower, but are limited to a throttle or firmware ECU. Removal of the restriction (deforcing) is often possible, but can lead to loss of warranty and requires professional intervention in the fuel system.
specifications comparison table
To make it easier to choose, we have prepared a summary table with the technical data of popular models, and pay attention to engine volume and weight, since these parameters directly affect the acceleration dynamics and handling of the vessel.
| Model | Type | Weight (kg) | Volume (cube.cm) | Features |
|---|---|---|---|---|
| Tohatsu MFS 9.8B | 4T | 27.0 | 169 | Electronic ignition of CDI |
| Yamaha F9.9B | 4T | 27.0 | 169 | Exhaust cleaning system |
| Hidea HD-F9.8FHS | 4T | 26.5 | 169 | Analogue Yamaha/Tohatsu |
| Parsun F9.8BMS | 4T | 27.5 | 169 | Reinforced lower unit pipe |
| Mercury 9.9M | 4T | 27.0 | 169 | Possibility of upgrade to 15 hp |
And when you look at the data, you can see that the weights of the market leaders are almost identical, and the differences are in the quality of the datawood materials, the cooling system, and the availability of service in your area. lower unit (motor leg) in expensive models often has an anti-corrosion coating, prolonging the life of the knot in salt water.
⚠️ Attention: Do not use motors that are not designed for salt water in marine conditions without thoroughly washing with fresh water after each exit.
Fuel consumption and economy
Fuel consumption is becoming increasingly important as fuel prices rise: 9.8 hp four-stroke engines average about 2.5-3.5 liters of gasoline per hour at full speeds. At cruising speeds of about 70-80% of the maximum, consumption drops to a comfortable 1.5-2 liters per hour.
Two-strokes consume 20-30% more fuel at the same load, and you also need to add the cost of operating a quality two-stroke oil, but if you take into account the lower weight of the 2T engine, the boat goes lighter, which partially compensates for the gluttony of the engine.
A standard 12-litre four-stroke tank can be used for about 4-5 hours of active work or a full day of economical fishing, an important parameter for long-distance route planning where refueling is not possible.
- ⛽ Cruising speed: optimal mode for fuel economy.
- 📉 Running in: The first tank of fuel is recommended to roll out in a gentle mode (50% of gas).
- 🛢️ Oil quality: Use only oils with a tolerance of TC-W3 for 2T and 10W-30/10W-40 for 4T.
Use a clear flask fuel filter to visually monitor the presence of water in gasoline and detect contamination in time, saving the carburetor from washing.
Features of operation and maintenance
Regular maintenance is key to the longevity of your engine. For four-stroke models, it is critical to change engine oil after the first 5-10 hours (break-in), and then every 50-100 hours of operation or once a season, ignoring this procedure will lead to bullies in the cylinder and expensive repairs.
After each operation, especially in dirty or salt water, it is recommended to wash the system with fresh water, and for this, many motors have a special connection or require a hose to be connected to the intake holes.
Ignition plugs must be checked and cleaned every 50 hours, replaced once a season or as a result of the charcoal, and the color of the charcoal on the candle electrode can tell you a lot about the engine: black dry soda indicates a rich mixture, white indicates a poor one, and brick-brown indicates the correct operation.
☑️ Seasonal engine maintenance
Installation and breaking in recommendations
The correct installation of the motor on the transom affects speed and fuel consumption. The motor must hang strictly in the center of the transom. The height of the suspension is selected experimentally: the anti-cavitation plate must be 1-2 cm below the bottom of the boat when moving. If you lift the motor higher, air suction and overheating will begin; if lower, water resistance will increase.
The process of running a new engine is not just a formality, but a necessary procedure for working out rubbing parts. For four-stroke engines, it is usually 10 hours. The first 2 hours should be run at idle speeds, then gradually increase the load, avoiding running at full gas (100% throttle) all the time.
During break-in, you can't let the motor run at the same speed for long, you need to change the speeds periodically so that the piston rings are properly rubbed against the walls of the cylinder along the entire height of the piston, which will ensure good compression in the future.
Quality break-in increases the engine life by 1.5-2 times. Do not save time at this stage, since it is in the first hours of operation that the "health" of the cylinder-piston group is formed.
⚠️ Attention: Never run the motor out of water (on land) without connecting to a water cooling system or a barrel of water. Dry work, even for 30-60 seconds, can cause the head of the unit and gaskets to deform due to overheating.
Frequently Asked Questions (FAQ)
Can you drive a 9.8 hp boat without a license?
In the Russian Federation, according to the rules of GIMS, registration of small craft and the availability of rights is not required if the weight of the equipped vessel does not exceed 200 kg, and the engine power is less than 10.88 hp (8 kW). The engine 9.8 hp formally fits these requirements, but the total weight of the boat with the engine, battery and equipment should not exceed 200 kg.
Which petrol is better to fill: 92nd or 95th?
Most modern four-stroke engines with a capacity of 9.8 hp are designed for gasoline AI-92. Using AI-95 does not give a gain in power, but can lead to faster valve burnout due to higher combustion temperature, as these engines often have a low compression ratio. Always check the manufacturer's instructions (manual).
Why does the engine stop at idle speed?
The most common causes: a contaminated carburetor (idle jicler), improper adjustment of the screw quality of the mixture, air sucking through the gasket of the carburetor or the crankshaft glands. It is also worth checking the ignition system and the state of the candle. In four-stroke engines, the cause may be low oil levels and the emergency stop sensor.
Do I need to drain the oil from the gearbox for the winter?
Yes, it's a mandatory procedure when preserved. Even if the oil looks clean, it can contain condensate (water) that will expand when frozen and damage the glands or the casing of the gearbox. Replace the oil before storage so that the new lubricant protects the gears from corrosion.
To sum up, the choice of 9.8 hp engine depends on your specific tasks. four-stroke model Tohatsu or YamahaIf the priority is the minimum weight and simplicity of the design, it is worth looking at the proven ones. two-stroke In any case, timely maintenance will ensure that the engine will serve you faithfully for many seasons.