The throttle valve determines the amount of air to supply, and engine power directly depends on this.
Fuel is sucked into the carburetor system by a pump (its membrane). Then it passes through a fitting in the carburetor. Next, the liquid moves through the inlet and outlet valves of the pump. Filtered out by the grid. It moves through the needle valve into the membrane chamber.
The level of air density in the system depends on the area of the open air damper.The wider the damper is open, the greater the fuel consumption and power.
Simply put, adjusting the carburetor on a lawn mower is creating the optimal fuel mixture due to the correct air supply.
You need to find the maximum idle speed. To do this, slowly turn the screw (L) to the right and left.
To adjust, turn the screw a quarter of a turn, always counterclockwise.
From the left screw (H) depends on the overall adjustment of maximum speed, engine power, temperature and gasoline consumption.
Setting up the carburetor of the lawn mower with the last screw is done as follows:
Interestingly, from the point of view of the author of the video, the setting (its correctness) is determined by the color of the candle, and not just by the engine speed and stability.
Very often, complaints from owners of gasoline trimmers are associated with various kinds of carburetor malfunctions. Of course, it is best in this case to seek help from specialists in this field, for whom the repair of gasoline trimmer carburetors is an integral part of the profession. However, if you are still familiar with the basic principles of the trimmer carburetor, you can try to figure out the problem yourself so as not to overpay money in the service, since sometimes a breakdown can be really not serious.
This article is just designed to help you deal with the problem.
Next, the most common breakdowns and the reasons for their occurrence will be disassembled.
The first step is to inspect the carburetor as a whole and find out if fuel is leaking.
If it turns out that there are no problems with fuel, it is necessary to remove the carburetor from the engine and check the condition of the gasket located next to the carburetor.
If no malfunctions are observed here, you can try to check the carburetor for a degree of tightness.
To do this, you can purchase a special device, which is part of the tool kits for repairing the carburetor repair of lawn mowers and which is a special pressure gauge, which, in fact, checks the tightness.
If you don’t want to spend money on its purchase, you can use an ordinary medical tonometer, on which you just need to change the pressure gauge.
When using this device, pay attention to the indication.
If the pressure does not drop and remains the same for a long time, you can be calm, as this indicates the tightness of the carburetor.
If the pressure begins to decrease after a certain time, then there are still problems.
They may be associated with damage to any parts of the carburetor.
Before you run to the nearest repair shop or a specialized store selling trimmers and spare parts, try to figure out the problem yourself. Sorry for the banality, but the motokosa carburetor is not an extraterrestrial spacecraft, and it is quite possible to repair it yourself. To be sure of your actions, read the step-by-step instructions provided in this article.
VIDEO
A visual inspection of the carburetor will help identify fuel and air leaks, but the main causes of device failure lie inside. Therefore, in order to determine and most importantly correct the breakdown, the carburetor must be disassembled.
To disassemble the carburetor of lawn mowers, a lot of effort is not needed.
It is enough to unscrew the four screws on one side
and two on the other. This can be done with a regular Phillips screwdriver. Carefully unscrew the screws and fold to the side. They may be needed during assembly. It is advisable to cover the table with a white cloth before disassembly so that everything can be seen, even the smallest details that may fall out during disassembly.
We begin disassembly from the side of the fuel supply system.
We remove the primer - the swap bubble, which is noteworthy, it is simply impossible to install the carburetor parts incorrectly during assembly. Products have characteristic ebb and flow.
Now remove the membrane. It is she who performs the function of pumping fuel into the carburetor.
When the membrane vibrates, the other side exerts pressure on the rocker arm of the mechanism and the needle rises, which, in turn, opens the hole and fuel is supplied.
Remove the carburetor cover with the injection mechanism.
Next, another membrane is installed. We carefully remove it.
Under the membrane is another gasket. We also carefully clean it, without damaging it in any way.
Next, we proceed to the dismantling of parts from the back of the carburetor. As mentioned earlier, unscrew the two bolts. This is the air supply system.
There is a valve here, which, when "gas" is added, opens and increases the flow of air into the engine.
After removing it, a bare body remains in the hands. Carburetor disassembled.
Troubleshooting and Troubleshooting
Now you should pay attention to the problems that occur during the operation of the carburetor and how to fix them.
The first thing that happens is the holes and jets in the fuel supply system become clogged with dirt. The filters installed in the tank and directly in the carburetor do not help. They still allow small particles to pass through, which cause the scythe to fail.
Now we need to get the needle.
To do this, unscrew the bolt on the mechanism, holding it with your finger. The fact is, there is a spring there and careless action will lead to the fact that it will be lost.
We take out the needle, see the photo and the spring.
How to purge. The most effective way is to use an ultrasonic bath.
It is filled with either a special liquid or gasoline, a carburetor is placed there and under the action of ultrasound, the so-called cavitation effect, the channels are cleaned of dirt.
The second cleaning option is compressed air.
You can use the compressor available on the farm and clean the carburetor channels. However, this method is effective if the contamination is not very large.
If there is neither an ultrasonic bath nor a compressor at hand, then cleaning can be done in a third way using a special cylinder for cleaning the carburetor. They are sold in almost all car dealerships and supermarkets. The price is low and is about $ 2-3. Enough of such a cylinder for 4 or 5 purges.
Now we need to blow through the channels in the body and carburetor cover. See photo.
Another particle of dirt can get stuck under the needle. See photo.This will also lead to the failure of the scythe.
Important! When cleaning the carburetor, in no case should you use needles, pins or wires. Even the slightest scratch will destroy the carburetor. It will have to be changed entirely.
It is located on the carburetor cover and is a fine metal mesh. Its pollution occurs very often. This is due to the deposition of oil, additives, and dirt on it.
Sometimes, when disassembling into grids, a certain film is found. According to this carburetor, there is not enough fuel and the lawn mower either does not start or works intermittently. The cleaning methods are identical to the first reason: an ultrasonic bath, a compressor or a spray can with a special solution. In addition, if the mesh is clogged thoroughly, you need to take a soft brush for watercolors, soak it in gasoline and rinse it gently without damaging it.
They have the ability to wear out during operation. From prolonged use, they deform, stretch, lose elasticity, low-quality fuel corrodes them, and can no longer perform their functions well. This also applies to the needle itself. The fact is that it is covered with a thin layer of rubber, which wears out during operation and can no longer fit tightly into the hole. Motokosa starts to work intermittently. To eliminate such a breakdown, it is necessary to replace all worn parts. Where to get them?
In specialized stores of garden equipment, a repair kit for a carburetor of a lawn mower of a certain model is sold. The cost of such a repair kit ranges from 40 to 60 hryvnia.
It includes two diaphragms, a gasket, a needle valve and a spring.
All carburetor wear parts can be replaced. Therefore, you should not rush and buy a new one, and you don’t need to run to the workshop either, repairs can be done by any user of lawn mowers. Professionals claim that the quality of the components in the repair kit even exceeds the characteristics of native carburetor parts. Therefore, a well-repaired unit will work better than a new one.
In addition, the bubble button for manual fuel pumping may fail. The impact of gasoline on it leads to the fact that during long-term operation, the rubber corrodes and it begins to stick together or bursts under the influence of low temperatures, for example, during storage. The button should also be replaced if necessary. In addition, its cost is small and will not affect the size of the repair budget.
Based on the foregoing, we can conclude that there are only three main carburetor malfunctions: clogging of channels, contamination of the fine filter, and failure of components. In the first two cases, cleaning is enough, and in the third, a repair kit will help.
It is not difficult to assemble a lawn mower carburetor. You must perform all the steps in reverse order:
Install the spring and needle valve in the carburetor cap. While holding the spring with your finger, tighten the mounting bolt.
Screw the valve of the air supply system to the body of the product with two screws.
Flip the carburetor over and move on to assembling the fuel system. First you need to install the gasket.
Install the carburetor cover.
Install the main membrane.
Install the plate with the manual fuel pump button and tighten the four screws.
The carburetor is assembled and ready for further operation.
For the first time, repairing a lawn mowing carburetor may seem like a complicated process, but if you have to disassemble it a second time, then this procedure will not cause any particular difficulties.
If you have not found any of the listed problems in your carburetor, it is recommended to seek help from a specialized service.
Modern technologies and equipment allow us to produce the best and optimal technical solutions that become effective assistants in the arrangement of a summer cottage or personal plot. The green lawn and other plantings can grow rapidly, to tidy up the local area and mow the lawns, a lawn mower is used, which is also called a lawn mower or trimmer, a gas mower.
Traditional scythes are inconvenient and unsafe to use, they require a significant investment of time and own effort, which will help save gas scythes that combine functionality and practicality in their design. In the photo of the lawn mowers, you can see various high-tech devices that have a set of operational characteristics, including such parameters as increased productivity and a long service life.
A convenient and reliable trimmer is a technical device consisting of separate mechanisms, parts and elements that can wear out, become unusable and damaged during intensive use.
Even with regular technical inspection, care and careful storage procedures, such devices and their individual parts require repair and even replacement, all repair procedures can be done independently.
Brief content of the article:
The easiest way is to give the lawn mower for repair by allocating a certain amount of funds from the family budget; prompt and high-quality do-it-yourself repairs are no less simple and convenient if you want to understand the design of the lawn mower and fix all the problems.
Mass and piece production of trimmers is based on the use of generally accepted technology, a typical design scheme consists of certain elements and parts, it is important to know them when carrying out independent repair work:
top part. The basis of the whole structure, where all important elements are assembled, such as a starter, a carburetor and a lawn mowing engine;
middle part. A hollow rod, inside it there is a cable connecting the engine and the gearbox, which sets the cutting line in motion. This part contains fasteners for distributing the weight of the entire structure and a belt for fixing the trimmer on the belt of a person using the trimmer for its intended purpose;
Bottom part. It contains the gearbox and cutting elements, which are hidden under a practical cover, which protects the user. The casing provides an increased level of safety, preventing large fractions of debris, pebbles and glass from getting into a person while working with a lawn mower.
Knowing exactly the internal structure and principle of operation of the trimmer, you can independently carry out repair measures for the design or replace individual components that have become unusable using the repair instructions.
The most common and frequently occurring, self-correcting breakdowns of the unit include the following problems:
engine malfunction, due to which the lawn mower does not start and does not work;
increased vibration of the scythe rod, which complicates its intended use;
increased overheating of the gearbox, its accelerated heating during operation;
slow and weak functioning of the cutting line at insufficient speed;
clogging of the starter grill, causing the engine to overheat and refuse to work;
fast and frequent clogging of the carburetor due to the use of low-quality fuel;
clogging of the air filter if the measures for caring for the device are not followed.
All these problems can lead to the fact that the device will lose its ability to work, before ordering the necessary spare parts for the lawnmower, a visual inspection and diagnostics of the device should be carried out.
Individual spare parts and assemblies of the device require special attention, you don’t have to contact a professional master to check them, a set of diagnostic measures will help you to identify the consequence of a loss of efficiency with your own hands.
If the trimmer engine does not start or stalls immediately after starting, when the gearbox overheats or during the operation of the device, extraneous noises are heard and vibration is clearly felt, it is important to make a visual inspection and identify a non-working unit.
To optimize the preparatory measures before repair, a simple diagnosis should be carried out and a step-by-step check should be made:
the presence of fuel in the tank and lubrication in the main components;
serviceability of the spark plug and its performance;
cleanliness of the fuel and air filter of the lawn mower;
clogging of the outlet channel and breather of the device;
the quality of the fuels and lubricants used.
To determine the functional performance of the ignition of the lawn mower, it is necessary to determine whether the candle is working by testing the appearance of a spark when it comes into contact with the body of the functional device.
The spark plug itself can be replaced with a new one, after drying the candle channel, if necessary, the old element is also dried, cleaned with special tools and returned to its place.
In the process of inspecting the carburetor, it is worth paying attention to the possible leakage of the fuel used; in order to identify problems with the carburetor, the following measures must be taken:
purging the fuel hose to eliminate possible clogging of the element;
checking and replacing the gasket located between the engine and the carburetor;
determination of tightness and maintenance of constant pressure in the unit.
If necessary, you can personally disassemble and thoroughly clean the assembly using gasoline, cleaning the jet and channels is carried out using compressed air.
The gearbox transmits torque from the motor shaft to the cutting tool; its gears must be absolutely clean and lubricated with special grease during operation.
Conducting a technical inspection on your own once a season will eliminate the need to repair the gearbox or replace it, with the purchase of an expensive new unit.
The starter is necessary to bring the trimmer into working condition, its diagnostics consists in checking the tension of the cord engaged with the teeth of the starter coil, which are often destroyed during a sharp start.
A non-working starter in a lawn mower cannot be repaired; it must be replaced with a working unit as part of a mandatory technical inspection or a set of repair measures.
Separate attention and care require cutting elements, which must always be cleaned of dirt and mowed grass after use. Regular inspection and careful preparation of the device for operation will help to avoid costly and time-consuming repairs, and always be sure that the lawn mower is working.
On trimmers, in addition to electric motors, gasoline internal combustion engines are installed. This mechanism requires special attention to itself, because if it is incorrectly configured, it will either refuse to work, or will work intermittently and lose power. Basically, engine tuning consists in adjusting the fuel supply, and this is done using a trimmer carburetor.
It is almost impossible to cover all types of carburetors produced by manufacturers of gas trimmers. But, since the design of this module, as well as its principle of operation, is largely similar between different models, a generalized description of the processes occurring in the carburetor can be made. This information will allow the user to understand the principles of operation of the device, to eliminate the malfunctions that have arisen and to operate it correctly.
The basis of the trimmer carburetor is one-piece aluminum housing . Below is a diagram of this block.
At the bottom of it, there is a diffuser, which is also called Venturi nozzle (eighteen). Air is sucked in by the motor through this nozzle.
The smaller this hole, the faster the air flows, and the higher will be the level of its rarefaction in the zone with the smallest diameter.
At the top of the diffuser are fuel channels (11.12). Through these channels, the air flow draws gasoline. The fuel pump itself, jets and the system used to regulate the supply of a mixture of fuel with air, can be built-in or installed outside.
throttle valve (9) regulates the amount of air sucked into the carburetor. Its amount affects the power that the engine develops. The damper (7) serves for cold start. It must be closed if you are going to start the unit. After the engine has started, it needs to be opened, otherwise, the engine will immediately stall.
Pulse channel (1) connects the impulse chamber of the pump to the crankcase of the engine, namely, to its internal volume. The piston located in the cylinder, producing reciprocating movements, sequentially changes the pressure in the crankcase (vacuum or increase in pressure). Pressure drops cause the membrane (4) to move. Therefore, the operation of the pump is synchronized with the operation of the engine.
The suction of gasoline from the tank occurs precisely with the participation of membranes (4). Gasoline enters the carburetor through the fitting (2). Further, its path lies through the intake valve (3), exhaust valve (5), through the strainer (6), the fuel channel (10), passes by the needle (14) and fills the chamber (16), which has a control membrane (18) .
The valve (14) is connected to the diaphragm (18) by means of a lever (17). The cavity, which is located below the membrane, is connected to the atmospheric air through the hole (19).
The device operates as follows.
A vacuum is created in the diffuser during the suction stroke. This fact causes air leakage. The position of the throttle valve (9) determines the amount of air entering the carburetor chamber, as well as the engine power and the number of revolutions.
At this time, fuel is sucked from the chamber (16) through the jets (11,12), after which it mixes with the flowing air. Gasoline, mixing with air, begins to spray. Thus, it creates air-fuel mixture .
The finished mixture enters the cylinder, where it is compressed by the rising piston and ignites at its top point from the spark generated by the spark plugs.
Since the volume under the control membrane (18) is connected to the atmospheric air through the channel (19), the membrane goes up, opening the valve (14) by means of the lever (17). After opening the valve (14), a new portion of fuel enters the chamber (16).
After the chamber (16) is filled, the diaphragm (18) returns to its original position and the valve (14) closes.
Further, when the motor is running, all the above processes are repeated. To adjust the amount of fuel entering the diffuser through the jets, a screw (13) is used. A screw (15) is also used to set the idle speed. When the regulators are unscrewed, the fuel mixture is enriched, and when twisted, the mixture becomes lean. Also in some models of carburetors, you can adjust the idle speed of the engine quantity regulator . It is usually located outside and, when twisted, rests against a lever mounted on the throttle axis.
Thus, using 3 adjusting screws, you can achieve maximum engine performance, as well as set it to run smoothly at any ambient temperature, and even in mountainous areas.
Trimmer carburetor breakdowns occur due to the use of poor quality gasoline, a damaged air filter and the accumulation of dirt in the chamber of this block. Most often, it is quite possible to repair the carburetor with your own hands. The following are typical scythe carburetor malfunctions.
A common malfunction that "haunts" the fuel pump is pumping diaphragm deformation . For this reason, it does not fit properly and the pumping channels do not seal.
The causes of membrane deformation can be the following:
long trimmer operation;
use of unsuitable fuel;
ingress of gases into the impulse channel.
As a result, diaphragm damage reduces the performance of the pump, and as a result:
depletion of the combustible mixture occurs;
difficult to start the engine;
there are interruptions in the operation of the motor;
piston is damaged.
Also, the above-described consequences for the engine can cause clogging of the pump cavity with impulse side . In this case, dirt enters the membrane through the impulse channel.
To eliminate the blockage, you will have to disassemble the carburetor and clean the membrane.
The strainer can become contaminated when contaminated fuel enters through a defective fuel hose or suction head. In the photo below you can see how a clean filter and a dirty filter look like (the parts are separated by a line).
To eliminate the malfunction, a thorough cleaning and rinsing of the strainer will be required. Also recommended blow with compressed air all holes in the trimmer carburetor body.
This failure occurs when the contact surface of the lever wears out.
Erasure of the contact surface occurs due to the presence in gasoline abrasive particles or due to strong vibration of the motor during operation. This defect in the adjusting lever causes intake problems, as well as improper idling of the engine.
The inlet needle fails, as a rule, due to the presence of abrasive particles in the composition of the fuel fluid.
the tightness of the inlet needle seat is violated;
there is a leakage of the combustible mixture;
there are malfunctions in the operation of the engine associated with the re-enrichment of the fuel mixture.
Also, the inlet needle can simply jam.
A stuck inlet needle can cause the presence of dirt in the fuel , or a long downtime of the device without work.
If dirt accumulates in the adjusting cavity, then the inlet needle cannot tightly close the hole and a lot of fuel is poured into the chamber.
It causes reenrichment of fuel and the engine starts to run incorrectly. It is necessary to disassemble the carburetor and clean the cavity of the adjusting membrane.
The membrane may be subject to deformation during prolonged operation of the unit and when using aggressive fuel.
The impossibility of normal adjustment due to a defect leads to:
piston damage;
difficulty starting;
fuel depletion;
incorrect engine operation.
This problem may occur if the adjusting lever is installed incorrectly or bent before installation. As a result, the contact surface assumes an incorrect position, which disrupts the additional fuel supply.
The throttle and air dampers are mainly worn out due to the presence of abrasive particles in the air. Defective shutters look like they have been sandblasted.
As a result of valve wear, engine performance decreases, malfunctions appear in its operation, piston rings, piston and cylinder coating wear out.
The choke and throttle shaft can wear out for the following reasons:
insufficient and improper maintenance of the air filter;
the air filter is damaged;
the air filter is not suitable for this unit.
Due to hit poor quality air , the shaft wears out and may break. Broken shaft parts can enter the combustion chamber or crankcase and cause serious damage to the entire piston system.
To eliminate problems with air purification, it is necessary to replace the defective filter or rinse the existing (serviceable) one. The filter must be washed in soapy water and dried.
Carburetor adjustment is necessary in the following cases:
the new engine was run-in (4-5 liters of fuel mixture were used);
the composition of the fuel has changed (brand of oil and gasoline);
the weather has changed (became hot, cold);
air rarefaction has changed (concerns mountainous areas);
after long-term storage;
the load on the engine has increased (after changing the tool, etc.);
due to vibration, the adjustment screws spontaneously unscrewed;
fuel consumption has increased, the carburetor pours fuel;
soot quickly appears on the electrodes of the spark plug (while the fuel mixture is prepared correctly);
the engine starts and immediately stalls or gains momentum poorly;
gasoline does not enter the cylinder;
a large amount of exhaust gases.
Before you start setting up the trimmer carburetor, you must do the following:
flush the engine;
replace or clean the spark plug;
change to a new one or clean the air filter (it is recommended to wash it in warm, soapy water, wring it out and let it dry well).
It is also necessary install cord of a suitable diameter into the trim coil or install knives - this is done so that the engine has at least some load during the tuning process. After installing the cutting tool and starting the gasoline engine, allow it to warm up for 10 minutes.
If at idle engine, you notice that the cutting tool is rotating, which means you need to reduce engine speed. This is done using the lower idle control, often marked with the letter “T”. The picture below shows the placement of the controls on a Husqvarna trimmer.
But, for example, on a Stihl trimmer, this screw may be marked “LA”.
So, turn the idle speed control to the left until the trimmer head stops completely.
To adjust the carburetor, 3 regulators (screws) are used.
Right knob L adjusts the level of enrichment of the combustible mixture at low speeds. It needs to be adjusted first. Achieve maximum idle speed. This is done with the L knob, turning it left and right. After finding the point of maximum speed, return the regulator a half turn to the left (counterclockwise).Lower adjuster T (LA) used to set the idle speed. By turning it to the left, the engine speed will begin to decrease, and by turning the knob to the right, the engine speed will increase.Left knob H is responsible for the enrichment of the combustible mixture at high speeds. The enrichment setting completes the carburetor adjustment. Also, using this regulator, you can adjust the maximum speed, fuel consumption and engine power.Important! If the engine is allowed to run at full speed for more than 10 seconds, it may fail.
To eliminate this trouble, adjustment is required. With the engine running, give full throttle, then turn knob “H” to the right until the RPM starts to decrease. After that, the "H" knob must be slowly scrolled to the left until you hear the uneven operation of the engine. Then turn knob “H” to the right until you hear a smooth running of the motor.
After carrying out the above steps, the carburetor setting can be considered completed. After correct adjustment, the engine should confidently pick up speed, slightly quarter at maximum speed, and when idling, the cutting tool should not rotate. This manual is suitable for adjusting carburetors on Huter, Patriot and other lawn mowers.
There are also screwless carburetors , responsible for the enrichment of the combustible mixture at low speeds. That is, they have only 2 adjusting screws: the idle speed regulator and the fuel mixture quality regulator at high speeds. How to set up this type of carburetor can be found in this video.
Video (click to play).
VIDEO
