Motokos starts and immediately deafens: diagnosis and elimination

When trying to start a gasoline trimmer, the engine can grab for a split second, emit a characteristic flash sound, but immediately stop, without going into a stable operating mode. This behavior indicates a violation of the balance of the fuel mixture or the absence of a spark at a critical moment when the turnover should grow. Most often, the problem lies in clogging of the jelly carburetor, violation of the ventilation of the fuel tank or the appearance of a sucker of unaccounted air in the exhaust tract. Ignoring the symptom “starts and stops” leads to the fact that the device becomes unsuitable for operation, requiring immediate disassembly and defective nodes.

Owners often mistakenly believe that it is enough to simply pump fuel, but if the motokos dies immediately after the start, then the combustion process cannot be maintained constantly. This can be caused by the fact that too little gasoline gets into the cylinder when open throttle or, conversely, the mixture is enriched so much that there is a “clutter”. It is also worth considering the state of spark-plugIf it is wet and black, the spark can break through inefficiently without igniting the mixture at high revs. Accurate diagnosis requires a consistent check of each system, from air supply to compression.

It should be understood that the two-stroke trimmer engine is extremely sensitive to the quality of the mixture and the tightness of the system. If you notice that the spit works only on the sucker, and when opening the valve of the carburetor, the revolutions fall to zero, this is a sure sign of violation of the proportions of air and fuel. In some cases, the cause is banal soak on the piston or muffler coking, which does not allow the exhaust gases to freely go out. Further operation in this mode can lead to overheating of the piston group and bullies.

Problems with the fuel system and carburetor

The most common cause of unstable work is pollution carburettor. Even microscopic debris particles or resinous deposits from old gasoline can block the thinnest channels through which fuel enters the combustion chamber. When you try to get a spit, the starting amount of fuel is enough to flash, but there is no constant flow through the jellyboxes and the engine dies. This is especially true if the tool has been standing for a long time without the gasoline drain.

The second important aspect is the condition of the fuel filter and hoses. If fuel-filter inside the tank is clogged with dirt, gasoline simply does not have time to come in the required volume. Hoses eventually tan, crack and begin to suck air, which impoverishes the mixture. Visually check the integrity of the pipes can be sprayed with fuel when the engine is running: if the speed changes, then the tightness is broken. It is also worth checking whether the fuel line inside the tank is squeezed.

Special attention is required by the membrane mechanism of the carburetor. If an elastic membrane has lost its properties, become rigid or break, it will not be able to create the necessary discharge to suck the fuel. As a result, the motokos dies when trying to add gas, as the supply of the mixture stops. Replacing a carburettor remake often solves the problem, but requires fine tuning of the quality screws and the amount of afterward mix.

⚠️ Attention: Never leave gasoline in the tank and carburetor for long-term storage. Evaporation of the light fractions leads to the formation of a sticky resin, which clogs the jellyclera and puts the carburetor out of action.

A simple method can be used to quickly check the fuel system. Disconnect the fuel supply hose from the carburetor and blow it. The air must pass freely, and when blowing out of the tank there should be no resistance. If the gasoline is flowing barely or in jerks, the problem is in the tank, filter or hoses. Cleaning the carburetor with ultrasound or special aerosol cleaners helps restore the permeability of the channels in most cases.

Failures in the ignition and candle system

The ignition system in gasoline trimmers is usually reliable, but it is also prone to failures. If the motokos starts and dies, the first thing you need to twist spark-plate and examine her. Nagar, black oily plaque or wet electrode indicate a violation of the combustion process. A dry, light brown or whitish candle indicates a poor mixture or overheating. A wet black candle often causes the absence of a spark under load, as the current goes on the soak, without creating a discharge.

It is important to check the gap between the candle electrode. The optimal distance is usually 0.5–0.7 mm, but the exact values depend on the engine model. Too much clearance requires a high voltage that the coil (magneto) may not provide, especially when heated. Too small a gap gives a weak spark, which is not enough to ignite the rich mixture. Adjustment of the gap is made by careful bending of the side electrode.

In addition to the candle itself, the problem can lie in the ignition coil or high-voltage wire. When heated, the insulation of the wire can crack, and the spark begins to “pierce” the mass of the body, bypassing the candle. This often manifests itself as follows: a cold spit starts and works for a couple of minutes, heats up, after which the spark disappears and the engine dies. Visually in the dark you can see a spark jumping outside the coil or on the wire.

⚠️ Attention: When checking for a spark, never hold a candle in your hand and do not touch the metal parts of the engine while scrolling with the starter. This can lead to an unpleasant, though not fatal, shock, and damage the electronic ignition system.

Another hidden cause is the violation of the thermal gap between the coil and the flywheel magnetic conductor. If the gap is too large, the spark will be weak or disappear when heated. For adjustment, a special plastic or paper gasket is used, which is installed between the coil and the flywheel magnet when tightening the fasteners. Proper installation of the gap ensures stable spark formation at any speed.

Contamination of muffler and exhaust system

Two-stroke engines work on a mixture of oil and gasoline, which inevitably leads to the formation of sodium. Over time, combustion products accumulate in the cylinder muffler and exhaust channel. If the motokos starts, but immediately dies when the throttle is opened, this is a classic sign that the exhaust gases have nowhere to go. The pressure in the cylinder increases and the engine “chokes”.

For diagnosis, it is necessary to remove the muffler (if the design allows) and inspect the outlet. It is often completely covered with heavy soot. In some trimmer models, the muffler is indissoluble, and then it is required to replace it or neatly burn the sodium (with observance of fire safety measures). It is also worth checking the condition of the exhaust window on the cylinder itself - it can also overgrow with coke.

The coar in the muffler not only reduces power, but also increases the temperature of the engine, which leads to overheating of the piston group. If you ignore this symptom, a melting of the piston or jamming of the engine may occur. Regular prevention, including the use of quality oil and the addition of additives, helps reduce the rate of formation of deposits.

Air suction and leakage

The internal combustion engine works as a pump, and any leakage in the intake system leads to a violation of the composition of the fuel mixture. If excess air gets into the crankcase or intake manifold, the mixture becomes too poor. The motokos can start on an enriched mixture (with the valve closed), but once you try to open the throttle to work, the excess air will lead to the impoverishment of the mixture and stop the engine.

Main air suction locations:

• 🔹 Gasting between the carburetor and the cylinder (often dries or bursts).
• 🔹 The crankshaft coils (when worn, air is allowed inside the crankcase).
• 🔹 Cracks in the carburetor or intake manifold.
• 🔹 The carburetor's loosely twisted bolts.

Check the presence of a suction can be in several ways. The easiest way is to spray WD-40 or a carburetor cleaner around the joints of the engine running (or trying to work). If the revolutions change, then the liquid got into the cylinder through the slit, which confirms the suction. A more accurate method is to check the compression and pressurize the crankcase with air under pressure with immersion in water or washing the joints.

Replacing the oils and gaskets requires partial disassembly of the engine. It is important to use original or quality analogues of spare parts, since cheap oil oils quickly tan and begin to pass air again. When assembly, it is necessary to monitor the purity of the surfaces of the adjoining and the correct installation of the glands (working edge inside).

Customization of the carburetor and the quality of the mixture

Proper adjustment of the carburetor is the key to stable operation of the trimmer. In most models there are three adjusting screws: L (Low) for low revs, H (High) for high and T (Idle) idling. If the motokos stalls when adding gas, the screw setting may have been knocked down L or H. Too poor mixture at low revs will not allow the engine to gain momentum, and it will stall.

The adjustment process usually looks like this: first the engine is warmed up, then the screw. T achieve stable idling (trimmer head should not rotate). After that, screws. L and H adjust the response of the engine to a sharp opening of the throttle. If a sharp press on the gas engine chokes - the mixture is poor (twisting the screw against the sentry), if smokes and loses momentum - rich (twisting the clock).

It is worth remembering that factory settings may not be suitable for specific operating conditions (height above sea level, temperature, fuel quality). Therefore, the final adjustment is always carried out “in place”. Using bad gasoline or oil with the wrong mixing proportion also requires reconfiguring the carburetor.

Table of symptoms and solutions

Symptom: Engine stalls at idle — Solution: Twirl the screw L or clear the idle channel.|Symptom: Deafens at sharp gas — Solution: Enrich the mixture with the screw L or check the fuel filter.|Symptom: Deaf at high revs — Solution: Set the screw H or check the air supply to the filter.|Symptom: Only works on the pump — Solution: Check the fuel system for blockages or air sucker.

Diagnostic table of malfunctions

To simplify the search for the problem, it is recommended to use a summary table. It helps to compare symptoms with the most likely causes and methods of their elimination. Remember that a single problem can cause several symptoms, so the diagnosis should be comprehensive.

Symptoms.	Probable cause	Elimination method
It will go off immediately after launch.	Filter or jellyfilter clogged	System washing, filter replacement
It only works on the suction.	Air suction or poor mixture	Search for leakiness, adjustment of the screw L
It's deaf when heated.	The heat gap of the coil or breakdown is broken	Adjustment of the coil gap, replacement of the BB wire
No power, deafening under load	Smuffler's full of sulphur.	Cleaning or replacing the muffler
Unstable turnovers, deafening	Water in fuel or old oil	Drain old fuel, refuel with fresh mixture

Using this table allows you to weed out obvious problems and focus on complex nodes. For example, if the braid dies only in the heat, first of all check the cooling system of the cylinder ribs and the adjustment of the mixture, and not climb into the carburetor immediately. The system approach saves time and money on spare parts.

Prevention and proper storage

To avoid a situation where the motokos starts and immediately dies, it is important to follow the rules of operation. The main cause of all the troubles is poor-quality fuel and its long-term storage. Gasoline with an octane number of 92 or 95 has the property of oxidizing and losing properties after 2-3 weeks. Therefore, it is impossible to prepare a mixture for the future for the whole season.

Proper storage involves a complete discharge of fuel from the tank and the production of residues from the carburetor. After the drain of gasoline, you need to give the engine to work for a few seconds to burn out the remains of the mixture in the carburetor. This will prevent the membranes from drying out and the needle valve sticking. You should also store the tool in a dry room, protecting from dust and moisture.

Regular replacement of the air filter is another key to the health of the engine. The dust-clogged filter restricts airflow, the mixture is enriched, the flow increases, and the engine is unstable. In conditions of severe dustiness (for example, when mowing dry grass), you need to check the filter every day. Washing the filter in soapy water and its thorough drying prolong the life of the piston group.

⚠️ Attention: Never use aggressive solvents to wash carburetor parts that can damage rubber and plastic elements. Use only special carburetor cleaners.

Keeping the mixing ratio of oil and gasoline is critical. For modern two-stroke engines, it is usually 1:40 or 1:50, for old ones - 1:33. Excess oil leads to coking and soot, lack - to overheating and bullying. Use only special oils for two-stroke engines with markings 2TConventional motor oils are not suitable and will quickly disable the equipment.

Final recommendations for repairs

If all of these methods have not helped and the motokos still starts and immediately dies, perhaps the problem is deeper. The wear of the piston group, damage to the crankshaft bearings or a crack in the crankcase require professional intervention and special diagnostic equipment. Attempt self-repair in such cases can lead to final failure of the node.

Cheap Chinese carburetors or membranes often do not keep the declared parameters even in a new state. When replacing nodes, it is better to choose original components or proven analogues from well-known brands. This will ensure the long and stable operation of your tool.

In conclusion, regular maintenance is the best way to prevent breakdowns. Simple activities such as using fresh fuel, cleaning filters and proper storage extend the life of the motokos for many years. If you are not confident in your abilities when setting up a carburetor or replacing glands, it is better to contact a specialized service center.

How to Check the Compression

For accurate diagnosis of the condition of the piston group, use a compressometer. The normal compression for most trimmers is 8-10 atmospheres. A value below 6 atmospheres indicates critical wear or occurrence of rings, which requires major repairs.

Why does the motokos die if you open the air valve after launch?

This is a classic sign that the engine can’t run on a normal mix. Most likely, the carburetor is too poor, or there is an air sucker. On the "suction" (closed valve) creates a strong depression that tightens the fuel even through small channels, but when the valve is opened, the thinning drops, and there is not enough fuel to maintain combustion. A partial blockage of the main jellywood is also possible.

Could a candle be the cause if there is a spark?

Yeah, maybe. Even if the spark is visually slipping, it may be too faint (red or orange instead of bright blue) or have an incorrect timing characteristic. In addition, if the candle electrodes are coated with a soda or oil is poured, the spark can only penetrate at low pressure (when scrolling with a starter), but disappear when compressed in the cylinder. Also important is the kalyl number of the candle: too "hot" candle can cause kalyl ignition and engine stop.

How often should the fuel filter be changed?

The fuel filter is recommended to be changed every season or when signs of pollution appear (the engine does not develop speed, stalls under load). However, if you use quality fuel and clean mixing containers, the filter can last for several seasons. Visually, it doesn’t have to be dark or sticky. The price of the filter is low, so it is easier to replace it prophylactic with every serious cleaning of the carburetor.

What if the scythe does not start after winter or immediately deafens?

Most likely, the carburetor dried gasoline and formed resin. It is necessary to remove and wash the carburetor, replace the membranes (re-kit). Also be sure to replace the candle and fuel in the tank. If the spit is stored correctly (with the fuel being drained), such problems should not arise. Check if the piston is oxide - try to gently turn the shaft with your hand (taking off the candle), it should rotate with little resistance.

Does the quality of the oil affect the fact that the braid is deaf?

Yeah, it's direct. Bad oil does not burn completely, forming a soda that clogs the muffler and exhaust window. This leads to loss of power and stop the engine. In addition, improper viscosity or oil properties can lead to piston rings sticking, which reduces compression. Use only oils designed for two-stroke air-cooled engines labeled JASO FD or ISO-L-EGD.