Choosing a power unit for an inflatable boat often turns into finding a compromise between power and weight that you have to carry to the water. For single fishermen or tourists crossing difficult stretches of shore, every gram matters. lightest petrol outboard motor available on the market, becomes critical when completing equipment.
Modern technologies allow manufacturers to reduce the mass of units without losing traction specifications, using new alloys and design solutions. minimum This article often dictates limits on engine capacity and, accordingly, on the maximum speed of the vessel. In this article, we will analyze in detail the market leaders in the ultralight class, assess their real capabilities and help determine the best choice for your conditions.
The main struggle for the title of the weightless unit unfolds in the segment of two-stroke engines with a capacity of 2 to 3.5 hp It is here that the models that can be confidently called record-breakersThis allows the motor to be transported in the backpack or trunk of a passenger car without the need for a trolley.
Criteria for the choice of ultralight outboard motor
When searching for the lightest model, you can not focus solely on the numbers in the passport. Dry weight The actual mass of the ready-to-operate unit will be significantly higher than the manufacturer's declared mass, which must be considered when planning loads.
The second important aspect is lower unitThe shortened leg of lightweight models is designed for low-transe boats, but in the wave, such a boat will be very splashy. In addition, the screw material plays a role: aluminum blades are lighter than composite blades, but when hit by a stone they crumple, rather than break, which can lead to vibration.
The ergonomics of the rummel should not be ignored either: in light models, it is often not possible to adjust the angle of inclination (trimming) on the move, and the fixation of the gas is carried out by a simple latch. Reliability of the ignition system Budget light motors can also vary, so having a CDI system is a must for stable operation.
⚠️ Note: When buying an engine, pay attention to the type of lower unit. Some lightweight models have a shortened lower unit leg, which makes them unsuitable for high-transcent boats or for anti-current driving when the boat is deep into the water.
Also important is the volume of the fuel tank: Built-in tanks in light engines usually have a capacity of 1.0-1.5 liters, which provides 3-5 hours of full gas operation. If you plan long transitions, you will have to carry spare canisters with you, which negates the advantage of the low weight of the engine itself.
Leadership rating: review of models up to 10 kg
Market analysis shows that the vast majority of ultralight engines are manufactured in China under the license of Japanese or European brands, or are direct copies of time-tested designs. Tohatsu, whose M series engines are considered the benchmark of reliability in the ultralight class.
Model Tohatsu M 2B2S It is often called the lightest full-fledged motor in the world, with a dry weight of only 7.5 kg (without a lower unit and a screw), and with full equipment it rarely exceeds 9.5 kg. The design is as simple as possible: there is no water-cooled pump (only air), which reduces weight, but requires strict control of temperature conditions during long-term operation at full gas.
Another strong competitor is the engine lineup Parsun and HDXChinese engineers have been able to copy the Tohatsu design by adding elements such as a built-in fuel filter and a more ergonomic ramp. The Parsun F2.6 BMS or HDX T 2.6 BMS models range in weight from 9.5 to 10.5 kg, making them an excellent alternative, especially given the more affordable price and developed service network.
- 🚤 Tohatsu M 2B2S The absolute leader in the minimum weight (from 7.5 kg), ideal for short distances and quiet hunting.
- 🛶 Parsun F2.6 BMS - optimal price-quality ratio, the presence of water cooling in some versions, weight about 9.8 kg.
- 🏎️ HDX T 2.6 BMS - popular model with improved exhaust system and reduced noise, the weight of the kit is about 10 kg.
- ⚓ Yamaha 2.5 CMHS - classic genre with a proven decades of design, reliable, but slightly heavier than competitors (about 12 kg with full equipment).
It's worth noting that there are also models with an electric starter in this class, but their weight immediately exceeds 15 kg due to the battery and the starter mechanism. minimum massManual launch remains an uncontested option.
Technical features and constructive
Understanding how to achieve these small dimensions will help in the operation. loop-blowing The cylinder, which allows you to abandon the complex valve mechanism, the fuel mixture (gasoline and oil) is fed directly into the crank chamber, where the pre-stirring occurs.
Cooling in most ultralight engines (up to 3.5 hp) is implemented according to the scheme "air + off-shore water" or only "air". The lack of a full water pump (impeller) eliminates the risk of clogging the cooling system with grass or sand, but requires caution when working at high speeds outside water or at shallow depth.
The secret of ease
Why are they so light?: The main secret lies in the materials. Carter is often made of magnesium-aluminum alloys, which are lighter than traditional aluminum. In addition, the exhaust system is simplified (the muffler is often combined with the exhaust pipe and goes directly into the water or air), and the lower unit is made as short and thin as possible, without unnecessary rigidity ribs.
The important feature is the lubrication system. Because these are two-stroke engines, the oil must be added directly to the gasoline. The ratio is usually 1:25 or 1:50 depending on the model and the break-in, the use of poor-quality oil or a violation of the proportions leads to rapid failure of the piston group.
⚠️ Warning: Never store a full tank of gasoline indoors or in the sun. Residues in the carburetor can evaporate, leaving a resinous plaque that will clog the jellyplants. Before long storage, run out of fuel completely.
specifications comparison table
To illustrate this, we're going to compare the key parameters of the popular models, and this is for a lower unit and propeller package, but no fuel.
| Model | Power (hp) | Weight (kg) | Type of cooling | Cylinder volume (cm3) |
|---|---|---|---|---|
| Tohatsu M 2B2S | 2.0 | 7.5 | Airborne | 23.2 |
| Parsun F2.6 BMS | 2.6 | 9.8 | Air/water | 33.0 |
| HDX T 2.6 BMS | 2.6 | 10.0 | Air/water | 33.0 |
| Yamaha 2.5 CMHS | 2.5 | 12.0 | Watery | 43.0 |
| Suzuki DF2.5S | 2.5 | 13.0 | Watery | 43.0 |
As you can see from the table, Tohatsu M 2B2S The models are 2.5-2.6 hp heavier, but they are more powerful and better adapted to go against the current or to fully load the boat.
If you want to keep the weight down at all costs, go for the Tohatsu M2. If you want versatility and traction, look for the Parsun F2.6 or Yamaha 2.5.
Operation and maintenance of light motors
Care for ultralight motors has its own specifics. Due to the compact design, access to some components can be difficult. Regularly checking the tightening of the diewut and tiller mount bolts is mandatory, since the vibration of the two-stroke engine quickly weakens the connections.
The spark plug must be twisted and checked every 50 hours or at the end of the season. The candlelight candlelight will tell you about the state of the engine: black plaque indicates a rich mixture or excess of oil, white indicates a poor mixture or overheating. Normal color is brick-brown.
- 🔧 ConservationBe sure to bleed the carburetor before wintering to remove any remaining gasoline.
- 💧 LubricantUse only quality two-stroke oils labeled TC-W3, designed for water cooling (even if you have air, the requirements for cleanliness of combustion are high).
- 🔩 VintCheck the screw for winding fishing line or grass after each fishing trip so as not to damage the glands.
Transportation of the motor must be carried out strictly in a vertical position or on a certain side (usually right, but it is better to specify in the instructions of a particular model).
☑️ Checklist before starting the engine
Challenges and solutions on the way
Even the most reliable petrol-engine The most common problem with light motors is to pour a candle with fuel when trying to start cold with the air valve closed. If the engine does not start after 3-5 jerks of the starter, most likely, the candle is flooded.
To solve the problem, you need to twist the candle, wipe it with dry rags and blow the cylinder, several times wiggling the starter with the twisted candle and open throttle. After placing the candle in place (without twisting to the end), repeat the start attempt. If the spark is dry, the engine will start.
⚠️ Warning: When you unscrew a candle on a running or newly running engine, be careful. The high-voltage wire must be grounded on the mass of the engine (pressed with a metal part to the block) to avoid electric shock, which, although not fatal, is very unpleasant.
Another common problem is loss of traction due to contamination of the fuel filter or jelly carburetor. Light motors often have simple mesh filters that are easy to clean but require regular maintenance, especially if you use gasoline from different gas stations.
Conclusion and final recommendations
Choice lightest gasoline outboard motor If you're fishing alone in small bodies of water, where every minute of assembly and carrying is important, models of up to 8-9 kg are the perfect solution, and they allow you to reach remote places where heavy equipment is simply impossible to carry.
However, if you plan to take active walks with a passenger or cargo, it is better to add a couple of kilograms of weight and take a 2.5-3.5 hp water-cooled engine, which will provide a power reserve and engine life, which in the long run will pay off with comfort and reliability.
Expert advice: When buying a used light engine, be sure to ask the seller to start it on water. Visual inspection will not show the state of compression and tightness of the osteoils, and the working engine will immediately give out all its shortcomings by the sound of exhaust and vibration.
Remember that the lightness of the motor should not be at the expense of safety. Always carry a spare candle, tool kit and emergency start cord (if the engine design allows it), Proper operation and timely maintenance will allow your light assistant to serve faithfully for many seasons.
Frequently Asked Questions (FAQ)
Can a four-stroke motor be used instead of a two-stroke motor to reduce weight?
No, that's a misconception. Four-stroke (4T) motors are structurally heavier than two-stroke (2T) engines of similar power due to the presence of a valve system, oil in the crankcase and a more massive cylinder block. The lightest 4T engine weighs about 12-13 kg (for example, Honda BF2.3), whereas 2T analogues weigh 7-9 kg.
Which gasoline is better to pour into light engines?
Most modern lightweight motors recommend AI-92 or AI-95 gasoline, the main requirement is freshness of fuel and the absence of alcohol additives (ethanol can corrode rubber carburettor seals). Gasoline should not be stored in the tank for longer than 2-3 weeks.
Do I need to run a new lightweight motor?
Yes, it is mandatory. It is usually 10 liters of fuel produced (about 2-3 tanks), during this period you can not give full gas, it is recommended to work at 50-70% of the power to the piston group to wear off. The proportion of oil when running in is often slightly richer (1:25) than after it.
Why does the engine stop at idle speed?
It's probably contaminated with the carburetor's idle jettison or the screw quality adjustment, and it could be caused by air suction through the gasket between the carburetor and the cylinder, and it requires cleaning the carburetor and checking the intake tract.