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Legendary EPL 2U5 It remains one of the most recognizable and widespread engines in the post-Soviet space, despite the respectable age of the design. outboard It was designed as a mass vehicle for fishermen and hunters, with a simple and maintainable two-stroke system, valued by its owners for its ability to operate on a mixture of gasoline and oil, and for its relatively low maintenance cost compared to modern imported counterparts.
However, the operation of the 1970s equipment in modern conditions requires the owner to have a deep understanding of mechanics and readiness for regular use of the equipment. settingThe engine has its own specifications in the mixture formation and ignition system, which radically distinguish it from modern ones. two-stroke Without a proper maintenance approach, this unit can become a source of constant smoke and problems on the water.
In this article, we will take a closer look at the technical nuances, hidden opportunities and typical problems faced by owners. EPL 2U5 to the season, so that he delighted with traction and stable work, and not constant search for malfunctions.
Technical specifications and design features
On the basis EPL 2U5 It's a classic two-stroke, crank-chamber blowing system, and it has two cylinders that are vertical, which provides a good centering and vibration resistance when properly balanced, and it has a nominal power of 5 horsepower, which is enough for lightweight inflatable boats or small metal "kazak" to move two people with a load.
One of the key features of the design is the presence of decompressorThe decompressor mechanism is connected to the throttle control lever and works automatically when started, putting some of the pressure in the cylinders, and this solution was advanced for its time and is still relevant for engines with above-average compression.
The cooling system is implemented on the thermosiphon principle, where water circulates due to the difference in the densities of hot and cold liquid. The absence of a water pump (pump) simplifies the design, but imposes restrictions on the modes of operation: you can not keep the engine at high speeds without loading for long or, conversely, work on the “idle” for too long.
Weight performance also plays an important role: the dry weight of the engine is about 26 kilograms. For modern users, this may seem a lot, but metallic. crankcase Transportation is carried out in a horizontal or vertical position, but storage is possible only in a strictly vertical position to avoid leakage of oil from the gearbox.
⚠️ Attention, motor transport EPL 2U5 in the horizontal position is permissible only for short distances and necessarily after the complete discharge of fuel from the float chamber of the carburetor, otherwise the cylinder will be overflowing with oil.
For a deeper understanding of the capabilities of the unit, we will consider the main parameters in the summary table:
| Parameter | Meaning | Note |
|---|---|---|
| Power | 5 hp (3.7 kW) | At 4500-5000 rpm |
| Workload | 94 cm3 | Two cylinders. |
| Fuel mixture | 1:25 (break-in), 1:30 (operation) | Gasoline AI-92 + butter |
| Tank capacity | 12 litres | Removable tank |
| Transmissions | 1 (front) | Reverse is missing |
Power system: device and subtleties of the carburetor
The heart of the fuel system EPL 2U5 It's a K-36 carburetor or a modification of it, which is a differential-pressure carburetor, and it's sucked in by the pressure pressure pressure generated by the pistons in the crank chambers, and it doesn't require an electric gas pump, which increases reliability, but it makes the engine sensitive to the tightness of all the joints.
A critically important element is It's a fuel filter-settlement in front of the carburetor, and in older models, it was often a transparent flask that gets cloudy and cracks over time, and cleaning the knot regularly and replacing the net is a must-have before every season, because even a small motley can disrupt the operation. jelly.
The adjustment of the quality of the mixture is carried out by a screw located on the carburetor body. Factory setting is often too "rich", which leads to increased smoke and soot on candles. Experienced motorists recommend a slight impoverishment of the mixture by twisting the screw, but you need to do this carefully, monitoring the temperature of the engine.
Use only high-quality two-stroke oil labeled TC-W3. The use of cheap oils or workings will lead to rapid coking of the exhaust windows and loss of compression.
Special attention should be paid to the fuel hose. Rubber bluffs and cracks over time, which can lead to air suction. Air in the fuel system is the main enemy of stable operation, causing gas failures and spontaneous stop of the engine on the go.
Ignition system and electrical circuit
Nana The 2U5 has a contact magnetic ignition system that does not require a battery to operate, and the power source is a magneto located under the flywheel, and the interfer(s) and the capacitor are located inside the crankcase or under a protective casing, making them available for maintenance without fully disassembling the motor.
The main parameter that needs to be controlled is contact-gapIt should be strictly 0.25-0.35 mm. Too little gap leads to slight sparking and contamination of contacts, and too large to burn the contact group and interruptions in work at high revs.
The angle of the ignition advance also plays a key role. The EPL 2U5 is controlled by rotating the base of the interrupter or changing the position of the cam. Early ignition causes detonation and overheating, later loss of power and overheating of the exhaust system. The optimal moment of spark formation is selected experimentally or by tags on the flywheel.
⚠️ Attention! When checking the spark, never hold the candle in your hands and do not allow a discharge of a mass closer than 5-7 mm from the thread, so as not to damage the candle insulator and not to get an electric shock, although the voltage is low.
The exclusion method is often used to diagnose: if there is a spark but the motor does not start, the problem is most likely fuel or compression. If the spark is weak or absent, check the capacitor and the contacts of the interrupter. Often, oxidation of the contacts inside the magneto is the reason for the inability to start in wet weather.
☑️ Diagnostics of the ignition system
break-in and first start of the engine
Right. break-in - the pledge of long life of the piston group, new or restored The 2U5 cannot be loaded at full capacity at once, and the first hours of operation must be spent on an enriched mixture (oil to gasoline ratio of 1:25) and at revolutions not exceeding 70% of the maximum.
The process of grinding the rings and cylinders takes about 10 hours of work or the production of 3-4 full tanks of fuel, during which it is not recommended to reach full speed or work in one mode for a long time. Periodically you need to change the load, giving the engine to work at both medium and high speeds, but not limiting.
When running, watch the color of the exhaust carefully. Blue smoke is normal for a two-stroke, but if it becomes thick and black, then the mixture is too rich. If there is a metal ringing or knocking, operation should be stopped immediately to find out the reasons.
The secret to fast-run
Some motorists recommend adding a small amount (about 50 grams) of castor oil to the fuel mixture at the first refueling, which has excellent lubricating properties and helps create the original oil film on the parts.
After the first hours of operation, be sure to check the tightening of all screw joints, especially the hairpins of the cylinder head and carburetor. The vibration of the new engine can weaken them, which will lead to air sucking or loss of leakage.
Typical malfunctions and methods of their elimination
Despite the reliability, The 2U5 is not without childhood diseases. compressionIt can be caused by wear on piston rings, cylinder scoring, or the collapse of the crankshaft glands, and the signs of low compression are difficult starting and lack of traction.
The second common problem is overheating, and often it's not the cooling system itself that's to blame, but the use of low-octane gasoline or the wrong angle of ignition, and overheating can cause the piston partition to collapse, requiring the piston group to be replaced.
Engine trimming (working on one cylinder) usually indicates a problem with ignition in one of the cylinders or a violation of the fuel supply. You need to take the caps off the candles one by one: if the engine does not change when one of the caps is removed, then this cylinder did not work.
| A symptom. | Possible cause | Elimination method |
|---|---|---|
| The engine is dead on singles. | Sucked up by a blank jikler | Cleaning the carburettor |
| Vibration is strong. | Disbalance of the screw | Replacement or balancing of propeller |
| Engine knock | Wearing of the crankshaft bearings | Replacement of bearings and glands |
| No spark. | Chain break or breakdown | Magneto and wire checks |
⚠️ Attention! If you hear a foreign knock at the bottom of the lower unit, immediately turn off the engine, which may indicate the collapse of the propeller shaft bearings, leading to jamming and costly repairs.
Diagnosing most of the problems with EPL 2U5 should start with checking candles and the quality of the fuel mixture, as 80% of faults lie in the ignition and power system.
Modernization and tuning to improve reliability
Owners often resort to modernization EPL 2U5One popular way to do this is to install electronic ignition (e.g., from the vortex or specialized sets for the Moscow), which eliminates the need to constantly clean contacts and adjust gaps.
The exhaust system is also a tangible improvement, and the installation of a resonator muffler or the upgrade of a regular "bubbler" reduces noise and improves the purge of the cylinders, which adds a few percent of the power, but it is important not to break the hydraulic resistance to the exhaust, so as not to impair the cleaning of the cylinders from the exhaust gases.
Some craftsmen change the standard carburetor to a more modern membrane (for example, Walbro), which solves the problem of the engine in the inclined position and during sharp maneuvers of the boat. The regular float carburetor is sensitive to roll, and when a heavy chop the engine can stall due to the bareness of the fuel intake.
Installing the thermostat in the cooling system is another step towards increasing resource. Two-stroke engines often operate at too low a temperature, especially in winter or when driving against the current, which leads to increased gas production. Maintaining optimal temperature conditions prolongs the life of the piston.
Should I put a screw with a big step?
Increasing the pitch of the screw will raise the maximum speed, but will reduce the dynamics of acceleration and can lead to engine overload. EPL 2U5 The standard screw or its modern analogues with a step of 200-210 mm remains optimal.
Frequently Asked Questions (FAQ)
Which gasoline is best used for EPL 2U5?
The AI-92 is the best choice, and the AI-95 is not feasible because of the lower octane ratio of two-stroke engines and the presence of more additives that can form soda, the main thing is the freshness of the fuel.
Why is the engine more likely to smoke than usual?
Increased smoke can be caused by three reasons: too rich mixture (a lot of oil in gasoline), wear of piston rings (oil gets into the combustion chamber from the crankcase), or ignition problems (incomplete combustion of the mixture).
Can I keep the 2U5 engine outdoors in winter?
Plastic elements can crack with ultraviolet light and temperature changes, and inside the engine can form condensation, which will lead to corrosion, you need to store in a dry room, pre-preservated.
How often should I change the scalp?
Preventive replacement of the osteoils is recommended every 3-5 years of operation or when the first signs of air sucking appear (floating idle speeds, difficult start) It is cheaper to replace the osteoils in advance than to repair the jammed engine.