Legendary Whirlwind 25 It is considered one of the most popular and recognizable outboard motors in the history of domestic boating sports and fishing, and this unit, produced since the late 1960s, became the workhorse for thousands of owners of metal boats and boats of the Kazanka type, its popularity is due not only to the affordable price, but also to a relatively simple design that could be serviced even in the field.
Despite its venerable age, interest in this model is not fading, and many enthusiasts still successfully operate these engines or are engaged in their restoration. technical specifications It is required for both buying a used copy and for competent tuning or repair. In this article, we will analyze in detail all the parameters, from the power on the propeller to the nuances of the ignition system.
Whirlwind 25 It was designed as a versatile engine for planing small craft with a displacement of up to 800 kg. The design of a two-stroke internal combustion engine with crank-chamber purge ensured high torque at low revs, which was critical for entering planing under full load mode. Today we will look at what exactly is hidden under the aluminum casing of this engine.
General background and model history
Engine development Whirlwind 25 The project was conducted at the Kuibyshev Engine Plant (KMZ) and was designed to create a niche between the low-power Neptune-7 and the heavier Virg-30, and the serial production allowed to saturate the market with affordable equipment that became the standard for many fishermen, and the design was based on proven solutions, but the engineers managed to significantly improve the cooling and lubrication system compared to their predecessors.
An important feature was the possibility of using the motor in shallow water due to the system of lifting the lower unit. transom mounting The engine was fitted to a wide range of boats, and early engines were more massive in day-wooth, while later modifications underwent a number of design changes aimed at reducing weight and vibration.
It is worth noting that Whirlwind 25 Often confused with the Virg-M model, there are significant differences between the ignition system and the carburetor layout. The classic version was equipped with a magdino with a breaker-distributor, which required regular cleaning of the contacts. Later versions received electronic ignition, which significantly improved the reliability of the start and stability of work at high revs.
Technical specifications of the engine
At the heart of the unit is a two-stroke two-cylinder engine with reciprocating and looping blowing, with a cylinder displacement of 478 cubic centimeters, which, at a compression ratio of 6.0, allows you to remove the declared power of 25 horsepower. propeller It is usually lower due to transmission losses and is about 20-22 hp.
The power system is implemented through two K-33 carburetors or modifications thereof, which provide a mixture. An important parameter is the speed of rotation of the crankshaft: maximum power is achieved at 4500-5000 rpm, exceeding these values can lead to overheating and accelerated wear of the piston group.
To prolong the life of the engine Vortex 25 try not to keep it at full speeds idle - this leads to overheating of candles and pistons due to insufficient cooling by the incoming flow of water.
The engine is cooled with off-shore water by a centrifugal pump located in lower unit, and the pump’s performance is designed to provide efficient heat removal even when driving in salt water, although long-term use in the marine environment requires careful washing with fresh water to avoid corrosion.
Below is a table with the main parameters of the power unit:
| Parameter | Meaning | Unit of measurement |
|---|---|---|
| Type of engine | two-stroke, 2-cylinder | - |
| Workload | 478 | cm3 |
| Maximum power | 25 (18.4) | hp (kW) |
| Rotation frequency | 4500-5000 | min |
| Degree of compression | 6.0 | - |
Transmission and propeller
The transmission of torque from the crankshaft to the propeller shaft is carried out through single-stage reducerThe gearboxes are obliquely engaged, which ensures quiet operation and durability. The gear ratio is 2.08:1, which is the optimal balance between thrust and speed for medium-sized boats.
The most important transmission is the forward-neutral-back gear shifting mechanism, which is implemented by a clutch that moves along the strands of the paddle shaft, controlled by a tiller located on the vomit (tops), which allows the gears to be switched only when fully discharged, which is a prerequisite for maintaining the integrity of the slings.
⚠️ Attention: It is strictly forbidden to turn on the forward or back transmission when the carburetor throttles are open, which leads to instant cutting of the clutch strands or breakage of the gear teeth of the gears of the gearbox.
The standard propeller has a diameter of 240 mm and a step of 300 mm. However, for different operating conditions and types of boats, the step can vary. The use of a large-step propeller will increase the maximum speed on light boats, while a reduction in pitch is necessary for heavy boats or for the transport of goods so that the engine can reach working speeds.
Features of the gearbox vortex 25
The gearbox uses a conical pair of gears, and the lubrication is sprayed, so the oil level in lower unit must be strictly on the control plug, and using too thick oils in winter can cause the glands to be squeezed out when heated.
Dimensions, weight and fuel consumption
One of the key factors when choosing an outboard motor is its weight. Whirlwind 25 It is a heavy enough unit to be carried by one person, so installation on a boat often requires the help of a second person or the use of a transom trolley. The total weight with a full tank and oil increases to about 55-57 kg.
The overall dimensions of the engine allow it to be used on boats with a transom height of 380 mm. the length of the lower unit is standard, which makes the engine universal for most domestic PVC boats and metal hulls. However, on very light inflatable boats, such mass can be excessive and disturb the centering of the craft.
Fuel consumption is a sore subject for two-stroke owners, depending on the load and the setting of the carburetors. Whirlwind 25 consumes:
- 🔹 At idling: about 1.0 - 1.5 liters per hour.
- 🔹 When moving at half the gas (cruising speed): 8 - 10 liters per hour.
- 🔹 At full gas (maximum power): up to 12 - 14 liters per hour.
To ensure the autonomy of the standard fuel tank with a volume of 20-22 liters (often included or purchased separately) is enough for 1.5-2 hours of driving in intensive mode.
Real fuel consumption depends on the condition of the piston group and the correct adjustment of the carburetors. Clogged jellyclera can increase gasoline consumption by 20-30%.
Ignition system and electrical equipment
Early versions of the system had contact magnetic ignition (magdino MB-1 or MB-2) that did not require an external power source, as the current was generated by the magneto itself, but it required constant adjustment of the gap between the contacts of the interrupter (0.35-0.45 mm) and the replacement of the capacitors. The angle of advance of ignition was adjusted automatically by a centrifugal regulator.
More modern versions are equipped with electronically-ignition This is a huge step forward, and the non-contact system has no mechanical contacts that can oxidize or burn, and it provides a stable spark at any humidity and temperature, and it also makes it easier to start the engine.
The motor also has a generator under the light coil that is capable of producing voltage to power navigation lights or charge a small-capacity battery. Usually it is 2-3 Amperes at 12 Volts, which is enough to maintain the battery charge, but not enough for a powerful winch or sonar with high consumption.
⚠️ Warning: When installing electronic ignition on older models, make sure that the magdino flywheel is beatless. Even a small backlash can cause the ignition coil to fail or the switch to fail.
The starter uses a hand-held starter with a ratchet mechanism, the starter cord is wound on the flywheel pulley, and it is important to monitor the starter spring and the integrity of the cord, as a break at the wrong time can lead to an injury to the hand or the inability to start the engine away from shore.
Maintenance and typical faults
Durability Whirlwind 25 The two-stroke engine requires mixing AI-92 (or AI-93) gasoline with a special two-stroke oil in a ratio of 1:25 (for running) or 1:33....1:50 (for operation). Using pure gasoline without oil is guaranteed to lead to pistons and engine wedges in a matter of minutes.
A typical problem is clogging of carburetors, especially if the motor has been out of work for a long time. The fuel mixture loses its properties, and the resins clog the jellywood. Also, the crankshaft oal often fails, which leads to air sucking and the mixture is depleted, causing overheating.
☑️ Annual TO Whirlwind 25
Adjusting the carburetors is a delicate process, and you need to get the throttles to work in synchrony and the right fuel levels in the float chambers, and you can see that you're not adjusting properly.
- 🔸 « Failures in the sharp opening of gas.
- 🔸 Unstable idle turns.
- 🔸 Black soak on candles (rich mixture) or white plaque (poor mixture).
When storing the engine in the off-season, it is recommended to mothball the engine: drain the fuel, blow the carburetors and add some oil to the cylinders through the candle holes, turning the crankshaft several times, this will create a protective film and prevent corrosion.
Comparison with analogues and final conclusions
In his class. Whirlwind 25 It had no direct competition from domestic technology, and compared to Neptune, it was more powerful and better suited for planing, but heavier and harder to repair. Foreign counterparts of the time, such as Mercury or Yamaha, were better in weight, efficiency and noise, but cost much more and were in short supply.
Today's shopping. Whirlwind 25 It's justified in a few cases: if you already have this motor, if the budget is extremely limited, or if you're a fan of retro technology and like to dig in the garage. For commercial use or frequent long-distance hikes, it's better to consider modern four-stroke engines, which are quieter, more economical and more environmentally friendly.
⚠️ Warning: When buying used vortex 25 be sure to check the compression in the cylinders. It should be at least 6-7 kgf / cm2. The difference in compression between cylinders more than 1 kgf / cm2 indicates the need for repair of the piston group.
In summary, it can be said that Whirlwind 25 It is a harsh but reliable technique that requires competent handling and a hand from the right place, and with proper care, it can work for decades, transporting fishermen and tourists across the waters.
Where can I find the parts?
Whirlwind 25 spare parts are still manufactured and widely available in the water and used parts market, with carburetors, piston group kits and oil glands being the most sought after.
Frequently Asked Questions (FAQ)
Which gasoline is best used for vortex 25?
It is recommended to use gasoline brand AI-92 or AI-93. the use of fuel with a lower octane number can lead to detonation and overheating, and higher (AI-95/98) - does not give advantages and may contain additives harmful to old rubber seals of the carburetor.
Why does the 25th engine stop at high speed?
The most likely cause is a fuel supply violation (a fuel filter, a hose or a carburetor jelly) or ignition problems (a failure of the coil during heating, a malfunction of the condenser). It is also worth checking the tightness of the fuel tank and hoses - air sucking leads to impoverishment of the mixture.
Can I put Whirlwind 25 on a PVC boat?
Technically, you can if the trunk of the boat can withstand a weight of about 50 kg and has a rigid insert. However, for light inflatable boats, this engine can be redundant in power and weight, which will make the boat rolling and difficult to operate. It is optimal to use it on boats from 3.5-4 meters long with a hard or inflatable floor.
what oil to use in the gearbox vortex 25?
The gearbox is filled with a special transmission oil for outboard motors (usually labeled as Gear Oil). You can use the Tap-15V or imported SAE 90 viscosity analogues. It is important that the oil has additives against foaming and corrosion.
What is the maximum speed of a boat with a 25-speed motor?
Speed depends on the type of boat and load. On a light metal boat Kazanka-M with one driver, you can develop 35-40 km / h. On a heavier Kazanka-5 or with a full load, the speed will be about 25-30 km / h.