Choosing a reliable power unit for a small inflatable boat or light boat often comes down to finding the middle ground between power and weight. Japanese brand Yamaha It has been a leader for many years, offering time-tested solutions, especially 5 horsepower models that are ideal for fishing, hunting or leisurely walks in calm water.
Why is this particular power class that attracts the attention of boaters? Yamaha 5 hp This motor is often the maximum allowable power for light PVC boats, which does not require registration in GIMS (depending on the total weight of the kit). This engine is able to plane a small boat with one driver, providing speeds up to 20-25 km / h. However, before buying it, you need to understand the technical nuances so as not to overpay for unnecessary functions or, conversely, not to face a lack of traction.
In this article we will consider in detail specificationThe design features of the two-stroke and four-stroke versions, as well as the actual fuel consumption, you will learn how old models differ from the new series, and get answers to maintenance questions, which will allow you to make an informed decision when choosing a heart for your boat.
Basic technical parameters and specifications
Speaking of the Yamaha 5 hp engines, it is important to understand that under this name hides a whole family of engines. Basic specifications The classic two-stroke variant, such as the 2MHS series, is known for its simplicity and lightness, weighing only about 19-20 kg, making transportation possible even in the trunk of a passenger car without the use of a special trolley.
Four-stroke modifications, such as the F5CMHS, are heavier, weighing 25-27 kg, but this additional weight is due to a more complex design, including a lubrication system and valve mechanism. The key difference is the oil crankcase in the 4T models, which eliminates the need to mix gasoline with oil manually. The cylinder volume of most of these engines varies in the range of 80-100 cubic centimeters, which provides optimal torque at low revs.
The ignition system in modern versions has switched to electronic CDI, which guarantees stable start in all weather. Previously, contact systems or magdinos were used, which required more frequent adjustments. Also worth noting is the cooling system: all Yamaha 5 hp models are equipped with a forced water pump, although temperature control is still necessary on small strokes.
Comparison of two-stroke and four-stroke versions
Choice between 2T and 4T It's a perpetual boating dilemma, and Yamaha's two-stroke engines, the 2MHS or 2CMHS series, deliver power immediately, without failure, and have a simpler device, and the lack of a complex gas distribution mechanism makes them accessible even in the field, and they can tilt in either direction, which is important when fishing in overgrown waters.
Four-stroke models like the F5 are better off in terms of sustainability and efficiency, and they're quieter, and they don't transmit vibrations to the transom of the boat. Fuel consumption 4T engines are on average 30-40% lower than two-stroke counterparts of the same power, but they require regular oil change and are more sensitive to the roll of the boat while driving.
- 🚀 Dynamics: 2T motors gain speed faster and more easily get on plane mode with full load.
-
🔇 Noise: 4T units work much quieter, which is highly appreciated when catching cautious fish.
- 🛠️ Maintenance: Two-strokes are simpler in design but require preparation of a mixture; four-strokes are more complicated but more convenient in daily operation.
⚠️ Note: When using a two-stroke engine, strictly observe the ratio of mixing oil and gasoline (usually 1:50 for modern Yamaha oils). Using old or poor-quality oil will lead to the coking of candles and piston group.
Fuel consumption and economic efficiency
Economy is one of the main arguments in favor of buying an outboard motor. For the Yamaha 5 hp, the flow rate depends on the mode of operation and engine type. The two-stroke version in full gas consumes about 1.5-1.8 liters of fuel mixture per hour. When driving half-heartedly, when the boat has already gone into planing, the flow rate drops to 0.8-1.0 liters.
The four-stroke sibling has a more modest appetite: At maximum speed, it will eat about 1.1-1.3 liters of pure gasoline per hour, and at cruising speed, it can consume only 0.6-0.7 liters. If you plan long fishing trips for several days, the fuel savings for the 4T model become tangible.
It is important to consider not only the litter, but also the cost of ownership. Oil for two-stroke engines In a four-stroke engine, oil changes less frequently (usually once a season or every 100 hours), but it is larger when replaced. In the long run, 4T is more profitable despite the higher initial price.
To save fuel on a two-stroke engine, use only high-quality synthetic oil and measure exactly how much it is. Excess oil will not add power, but will increase the load on candles.
Table comparison of popular models Yamaha 5 hp
To organize information and simplify choice, we present a comparative table of the main specifications of popular modifications. The data may vary slightly depending on the year of production and the market.
| Parameter | Yamaha 2MHS (2T) | Yamaha F5CMHS (4T) | Yamaha 2CMHS (2T) |
|---|---|---|---|
| Type of engine | two-stroke | four-stroke | two-stroke |
| Weight (kg) | 19.5 | 27.0 | 20.0 |
| Workload (cm3) | 99 | 112 | 80 |
| Fuel consumption (L/h) | ~1.6 | ~1.2 | ~1.4 |
| Launching system | Manual | Manual | Manual |
As you can see from the table, the weight difference between two-stroke and four-stroke models is significant. If every kilogram matters to you, for example, when dragging a boat through the fibers, then you can see that the weight difference is significant. Yamaha 2MHS If comfort and silence are the priority, then the model is the best. F5CMHS out of competition.
Features of operation and maintenance
The reliability of Yamaha engines is legendary, but it requires compliance with operating rules. Regular maintenance extends the life of the unit for many years. First of all, you need to monitor the cooling system. Before each start, check the control stream of water, which indicates that the impeller pump will clog or break.
The lubrication of moving parts in two-stroke motors is due to the combustion of the oil mixture, so the quality of the oil is critical. In four-stroke analogues, you need to control the level of oil in the crankcase through the probe. Oil replacement It must be carried out after the first 20 hours of running and then every 50-100 hours of operation or once a year.
☑️ Seasonal engine maintenance
Storage is also important, and if the motor is not expected to be used for more than a month, it is recommended that the carburetor be preserved, so that the fuel faucet can be shut off and the engine can generate all the gasoline from the float chamber until it stops, so that the remaining fuel will not dry and the resins will form.
⚠️ Warning: Never store the motor upright on the screw or on the cylinder head, which can lead to water leaking into the cylinder (through the exhaust window) or oil leaking out of the crankcase (in 4T models).
Frequent malfunctions and methods of their elimination
Even the most reliable machines sometimes fail, and one of the common problems is that they're difficult to start. spark-plugIf it's wet and black, it means that the ratio of the mixture is broken or the air filter is clogged, and if it's dry, the fuel doesn't go into the cylinder, maybe the chickler of the carburetor is clogged.
Another problem is overheating pumps, the reason may be the use of the outboard motor at too high speeds without sufficient cooling (for example, when testing on a barrel without proper water supply), in such cases the thermostat (if it is designed) or the cooling shirt itself can get damaged.
- 🔥 Problems with spark: Check the high-voltage wire and cap for oxidation.
- 💨 Power loss: Often caused by overgrown lower unit algae or damage to the anticavitational plate.
- 🔊 Engine knock: Requires immediate stop and diagnosis of the shaking-piston group.
How to properly store the engine in winter?
For winter storage, completely drain water from the cooling system (turning the engine several times), replace the oil in 4T models, treat the internal cavities with anticory and remove the motor to a dry room in an upright position.
Final selection recommendations
To sum up, the Yamaha 5hp is a versatile soldier in a world of light motorization, suitable for light inflatable boats and small metal "kazak", and the choice of a particular model depends on your priorities: weight and simplicity or economy and comfort.
If you're a solo fisherman and you value mobility, the two-stroke version is the perfect companion. For family vacations and frequent trips, where sustainability and exhaust odor are important, you'd better look at the four-stroke version. In any case, when you buy products from this brand, you invest in durability.
The best choice for most users is the four-stroke Yamaha F5, unless weight is a critical limitation, due to its resource and low fuel consumption.
Remember, getting a new engine running properly is a guarantee of long service, and the first 10 hours of operation should be run at modes up to 70% of the maximum power, periodically changing speeds, which will allow the parts to get lost and ensure that all connections are leaky in the future.
Do I need to register the Yamaha 5 hp engine in GIMS?
Under current Russian legislation, registration is required for small vessels with an engine of more than 8 kW (about 10.8 hp). However, if the weight of the boat itself (without the engine) exceeds 200 kg, registration is required regardless of the engine power. For standard PVC boats with a 5 hp (3.68 kW) registration is usually not required, but always carry documents confirming the power and weight.
What kind of gasoline to fill in Yamaha 5 hp?
For modern Yamaha engines, it is recommended to use unleaded gasoline with an octane number of at least AI-92. The use of AI-95 gasoline is permissible, but not mandatory. The main thing is to monitor the freshness of the fuel and not store gasoline in the engine tank for longer than a month, as it loses its properties and forms resinous deposits.
Can I use the Yamaha 5 hp engine in salt water?
Yes, you can. Yamaha's engine casings are corrosion-resistant, but after each release into salt water, you have to thoroughly wash the engine with fresh water, and for that, you have a propeller nozzle or just a hose watering, and if you don't flush the salt, the corrosion will quickly destroy the aluminum parts and the cooling system.