The Whirlwind series has long been one of the most common engines in post-Soviet waters, and the 25-horsepower model occupies a special place here: it is a reliable unit that, if properly maintained, can operate for decades, providing a confident ride for both heavy metal boats and spacious "Kazak". Two-stroke engine This series has established itself as a "workhorse", requiring minimal intervention, but with specific features of operation.
Owners often face the need to adjust the fuel system or search for spare parts for the gearbox, since the design of the motor, despite its simplicity, has a number of nuances. K-36 carburetor And ignition systems can help you to fix most of the faults in the field, and in this article, we'll take a closer look at the unit, look at the typical problems, and give you some upgrade recommendations.
The model in question differs from its younger counterparts (20 hp) in its increased cylinder diameter and modified gas emission system, which allowed to remove additional power, while maintaining the overall layout and interchangeability of many units with previous modifications. Unlike the 20-horsepower version, the modification of 25 hp has altered gas distribution phases and a reinforced shaky-piston group.
Specifications and engine design
At the heart of the unit is a two-stroke two-cylinder engine with crank-chamber purges. The displacement is 422 cubic centimeters, which at a compression ratio of 6.0 provides the declared power. The design provides loop purges, which makes it easier to manufacture parts, but requires careful adjustment of the exhaust system to minimize the loss of fresh mixture.
The lubrication system works on the principle of mixing gasoline with oil in a ratio of 1:25 or 1:30 depending on the mode of operation and the quality of the materials used. It's important to noteThe use of modern semi-synthetic oils for two-stroke engines allows to increase the interservice interal and reduce the amount of soak on candles and pistons.
Cooling is done by off-shore water using a centrifugal pump located in lower unit. The pump's performance is directly dependent on the rotation of the crankshaft, so when idling, the cooling efficiency is reduced. When working at low speeds in hot weather, it is recommended to periodically give "gas" or use an external water source.
- 🚤 Engine type: two-stroke, gasoline, carburetor
- 🚤 Number of cylinders: 2
- 🚤 Working capacity: 422 cm3
- 🚤 Maximum power: 25 hp at 5000 rpm
- 🚤 Ignition system: Magdino MB-2 (contact) or electronic (on newer versions)
Features of the fuel system and carburetor
The standard equipment for this model is a carburetor. K-36 It's a float-type device with constant dilution, which makes the combustible mixture, and the main adjustment element here is the main and idle jeepers, and the position of the throttle needle.
A common problem for owners is unstable idling or failures when a throttle is opened abruptly, often due to clogging of the jellyboxes or a leakproof float chamber. Gasting The carburetor eventually bluffs and begins to pass air, which leads to impoverishment of the mixture and overheating of the engine.
For stable operation, you need to regularly check the fuel level in the float chamber and the condition of the filter element. A diaphragm-type gasoline pump located under the carburetor also requires attention: the membrane may lose elasticity, which will lead to difficulties with starting after prolonged downtime.
⚠️ Warning: When disassembling the carburetor, be extremely careful with the quality and quantity of the screws. Do not twist them to the point "from the soul", this will damage the saddle and disrupt the geometry of the needle, which will make precise adjustment impossible.
To prolong the life of the carburetor, install an additional filter of fine fuel cleaning (sludge) in front of the gas pump - this will save the jellyfish from fine rust from the tank.
Ignition system and electrical equipment
Most of the modifications have a contact magnetic ignition system of the type MB-2. It is simple and maintainable, but requires regular maintenance. The gap between the contacts of the interrupter should be 0.35-0.45 mm, and the angle of ignition advance is set at risk on the flywheel.
Many owners are switching to electronic ignition systems (EI), which eliminates problems with burning contacts and loss of spark at high speeds. However, the installation of electronics requires careful attention to the quality of connections and protection from moisture, because plug-in sensitive to breakdowns.
The magdino generator part provides power to the ignition system and battery charging (if there is a rectifier). At low speeds, the charging current may not be enough, so it is recommended to monitor the voltage in the onboard network when using powerful lighting equipment or sonars.
How to set the ignition without a strobe?
You can use the spark method. When you scrolle through the flywheel, find the moment the spark slips through. It should occur a little before the piston reaches the upper dead point. The exact position of the BMT can be found by inserting a soft rod (for example, from a sushi stick) into the candle hole and slowly rotating the flywheel, fixing the maximum departure of the rod.
Reductor and propeller
The gearbox is designed with a single gear wheel and a conical gear ratio of 2.08, which provides the optimal balance between thrust and speed. The propeller shaft rotates in slide or roll bearings (depending on the year of manufacture) that require lubrication.
The main enemy of the gearbox is water that enters through the glands. Regular change of oil in the gearbox (every 50 hours or at the end of the season) allows you to control the condition of the seals. If the oil has acquired an emulsion (belesh) color, then the tightness is broken.
A propeller with a diameter of 270 mm and a step of 300 mm is standard for this power. Installing a screw with a large pitch can lead to overloading of the engine, and with a smaller one - to loss of traction and torsion of the engine. Sponna The propeller is often cut off when hitting underwater obstacles, so always have a spare set.
| Parameter | Meaning | Unit of measurement |
|---|---|---|
| Transfer ratio | 2.08 | - |
| Rotor diameter | 270 | mm |
| Screw pitch | 300 | mm |
| Volume of oil in the gearbox | 0.35 | litre |
| Type of oil in the gearbox | Tap-15V/TSP-15K | - |
Typical malfunctions and methods of their elimination
Operating in harsh environments often causes a variety of breakdowns, and one of the most common problems is power loss, which can be caused by cocking exhaust windows, a fuel pump malfunction, or a maladjustment of the carburetor. Diagnostics You should start with a compression check and visual inspection of the candle.
Overheating of the engine most often indicates a malfunction of the pump or contamination of the cooling shirt. If the engine does not flow from the control hole or is running a weak trickle, you need to immediately turn off the engine and clean the system. Dry work even for a few minutes can lead to pistons being bullied.
Knocking at the bottom of the motor usually indicates wear on crankshaft bearings or rod bearings. Ignoring this symptom causes the rod to collapse and cause serious cylinder damage. crank-and-wheeler.
☑️ Diagnosis in case of loss of power
Tuning and improvement to increase power
Owners often want to squeeze the maximum possible power out of the engine. A popular method is to install a petal valve at the inlet, which improves the filling of the cylinder at high speeds and makes the engine work smoother, and polish the channels and install a more productive carburetor.
The exhaust system, in particular the installation of a tuned resonance muffler, improves the exhaust gas cleaning of cylinders and adds a few percent of power, but such changes require accurate calculations and are often carried out by trial and error.
And the propeller is also worth remembering: picking the propeller with the optimal pitch for a particular boat and loading can give you an increase in speed without interfering with the engine. Using screws made of aluminum alloys of increased strength or stainless steel also increases efficiency.
⚠️ Warning: Any engine modifications that involve changes in compression or timing require higher octane gasoline, and ignoring this rule will cause the piston group to detonate and rapidly break down.
The most effective and safe tuning of the vortex 25 is the installation of a petal valve and the precise adjustment of the carburetor for a specific screw.
Maintenance and conservation for the winter period
In order for the motor reliably to serve you for many years, you must strictly follow the maintenance regulations. Regular lubrication of all friction units, changing the oil in the gearbox and checking the tightening of the bolt joints are mandatory procedures.
In preparation for winter conservation, you need to completely drain the water from the cooling system to avoid rupturing the block when freezing. The carburetor should be free of fuel, and the cylinders should be preserved with oil. It is better to store the engine in an upright position in a dry room.
Timely painting of the external elements with anticorrosion compounds will protect magnesium alloys from oxidation. Visual inspection of the lower unit for cracks and dents will also be useful, since hidden defects can lead to water entering the lower unit pipe.
Do I need to shoot lower unit for the winter?
You don't have to take off your lower unit completely if you're sure the glands are tight, but if you're worried about water getting into the gearbox, you'd better disconnect the lower unit, wash it, and check the slits of the paddle shaft and the switching clutches.
Frequently Asked Questions (FAQ)
Which oil is best to fill in gasoline for Vortex 25?
The best option is high-quality mineral or semi-synthetic oils for air-cooled two-stroke engines (API TC class, JASO FC/FD). The mixing ratio is usually 1:25 (40 ml per 1 liter of gasoline) for running and 1:30 (33 ml per 1 liter) for permanent operation. The use of cheap oils can lead to piston rings.
Why does the engine stop when the throttle is opened?
Most often, this is a poor mixture at medium speeds, and the reasons may be: clogged main jet lacquer carburetor, sucking air through the gasket between the carburetor and the cylinder, or incorrectly exposed fuel level in the float chamber, and it is also worth checking the fuel filter and hoses for inflections.
Can I put 25 electric starters on the vortex?
Normally, the electric starter on the Vortex 25 was not installed, unlike the more powerful models (30, 32 hp). However, there are ready-made kits for reworking or homemade solutions that include the installation of a starter, a bendix on a flywheel and a battery pack. This requires the reworking of the casing and the mounting system.
What is the speed of the boat with the engine Whirlwind 25?
The speed depends on the type of boat, loading and condition of the propeller. On a light PVC boat or aluminum "Kazanka" with one person, the engine is able to reach a speed of 30-35 km / h. When fully loaded (3-4 people), the speed can drop to 20-25 km / h. An important factor is the correct installation of the motor along the transom and the angle of the trim.