How to adjust the carburetor of the STIHL fs 55 trimmer

Main problems and malfunctions of the carburetor.

Mesh filter. How to adjust a chainsaw, how to properly adjust the carburetor on a Husqvarna chainsaw. There are usually only two problems with this element:

In order to find out the cause of the breakdown, unscrew the fuel filter cap to remove the strainer. If dirt has simply accumulated on it, then washing it in gasoline or blowing it out will help.

If there is visible damage to the mesh filter, it is imperative to install a new one. There may also be damage to the fuel supply pipe (during repairs, it is practiced to check this element).

The carburetor starter almost always does not work due to blockages. You should use acetone or the same gasoline for washing.

Blowing clogged carburetor parts with compressed air is an acceptable and comfortable repair practice.

The throttle body, joints of carburetor parts, intake or exhaust pipes - all of these parts are subject to depressurization. adjustment of the carburetor of trimmer in the video in order to adjust the idle speed. How to adjust the carburetor on a scooter in your own. You can probably check it using a simple method - smear the problem area with soap foam.

Inlet needle wear

The inlet needle fails, usually due to the presence of abrasive particles in the fuel fluid.

Trimmer STIHL FS 55 Brushcutter Does not develop speed, stalls, we are sorting out the carburetor

the tightness of the inlet needle seat is disrupted;
leakage of the flammable mixture appears;
Engine malfunctions appear due to over-enrichment of the fuel mixture.

Also, the inlet needle may simply jam.

Sticking of the inlet needle can cause dirt in the fuel, or the device may remain idle for a long time.

Operating Instructions: Safety Precautions

The equipment described above must be used while wearing special clothing and using the equipment. Clothes should not interfere with work. You should choose one that fits well to the body. It is necessary to exclude wide sleeves that could get caught on bushes, wood or moving parts of the unit.

It is important to remove ties and scarves. This also applies to jewelry. Before starting the STIHL FS 55, you must wear protective boots that have rough soles. It is important to use a special protective helmet and glasses that will prevent damage to your vision.

If you often encounter the need to mow the grass on your property, then you can use modern devices such as trimmers or lawn mowers specifically for this purpose. Among other solutions on the modern market, there are lawn mowers that can be used to maintain the surrounding area in a well-groomed condition.

One of the important advantages of a lawn mower is that it is not tied to a power source according to the principle of electric units. But such equipment can be used even on uneven areas and in hard-to-reach places, this should include areas under bushes.

How to make the adjustment correctly

Before you start adjusting the trimmer , you must do the following:

flush the engine;
replace or clean the spark plug;
replace or clean the air filter (it is recommended to wash it in warm, soapy water, wring it out and let it dry thoroughly).

It is also necessary to install a cord of a suitable diameter in the trimmer reel or install knives - this is done so that during the tuning process the engine has at least some load. After installing the cutting tool and starting the gasoline engine, let it warm up for 10 minutes.

If at idle engine speed you notice that the cutting tool is rotating, then you need to reduce engine speed. This is done using the lower idle speed 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 this screw may be marked “LA”.

So, turn the idle speed control to the left until the trimmer head comes to a complete stop.

To adjust the carburetor, 3 regulators (screws) are used.

The right control L adjusts the level of enrichment of the fuel mixture at low speeds. It needs to be adjusted first. Achieve maximum idle speed. This is done using the L control, turning it left and right. After finding the maximum speed point, return the regulator half a turn to the left (counterclockwise).
The lower adjuster T (LA) is used to adjust the idle speed. By turning it to the left, the engine speed will begin to decrease, and when turning the regulator to the right, the engine speed will increase.
The left regulator H is responsible for enriching the fuel 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 operate at full speed for more than 10 seconds, it may fail.

To eliminate this nuisance, adjustment will be required. With the engine running, give full throttle, then turn the “H” control to the right until the speed begins to decrease. After this, the “H” regulator must be slowly turned to the left until you hear uneven engine operation. Then turn the “H” control to the right until you hear the motor running smoothly.

After carrying out the above steps, the carburetor adjustment can be considered completed. After correct adjustment, the engine should confidently pick up speed, quadruple slightly at maximum speed, and when idling, the cutting tool should not turn. This manual is suitable for adjusting carburetors on Huter, Patriot and other lawn mowers.

There are also carburetors without a screw, which is responsible for enriching 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. You can learn how to set up a carburetor of this type from this video.

You can adjust the carburetor of a lawn mower yourself

Petrol mowers, like all petrol-powered garden tools, are not difficult to maintain equipment. You can and should repair and configure yourself. For example, adjusting the carburetor of a lawn mower with your own hands is a matter of five minutes.

The carburetor from a lawn mower is a component in the power system. In it, like any carburetors, the process of mixing air and fuel (gasoline) takes place for further supply to the engine cylinders.

In this process, the main thing is the correct proportion of fuel and air, for which the carburetor .

Adjusting the carburetor of a lawn mower from a German manufacturer

The use of lawn mowers in landscaping work implies wear and tear, and sometimes even breakdowns of its devices. But since this tool cannot be classified as a complex household device, all breakdowns are only mechanical in nature, which can be corrected with your own hands

.
In some cases, it is sufficient to carry out adjustment work to return the tool to normal operating condition. One of these operations is adjusting the carburetor of the lawn mower manually. The carburetor's job is to mix air with fuel before it enters the engine. And if the proportions do not match, the trimmer will have visible malfunctions:

the engine stalls;
fuel is overused, accompanied by an abundance of exhaust gases.

The entire process of adjusting the carburetor of a lawn mower

brand provides only for debugging the position of three screws: L – adjusting the supply of gasoline in the spit at low speeds, H – adjusting high speeds and fuel consumption, T – debugging
idle speed
. So, if it is necessary to adjust the carburetor of a gasoline scythe of the 55 line or other types of this series, the following steps are performed:

The engine warms up (10 minutes of idling is enough).
Screw H is adjusted by turning left/right until the maximum idle speed is achieved.
From the found point, turn it counterclockwise ¼ turn, which will set the desired working position.
Setting the idle speed of the lawnmower carburetor occurs in the same way, by turning it counterclockwise (decreasing the speed) and clockwise (increasing the speed). A position of maximum stability of the motor operation is achieved in different positions.
Screw L is adjusted in the same way, with small turns bringing it to the maximum value.

The whole process is carried out by ear, therefore, for more successful work it is worth acquiring a tanometer. You can perform tool maintenance as accurately as possible from the specialists of Kosa Motors, as well as buy oil for the compressor and purchase all the necessary spare parts and components for timely maintenance.

STIHL FS 55 - carburetor adjustment (idle speed)

Carburetor adjustment

the Shtil FS 55
trimmer in the video to adjust the idle speed.

Carburetor repair for STIHL FS55 lawn mower

Replacing the O-ring, accelerator in the carburetor of a STIHL FS55

How does a gas trimmer carburetor work?

It is almost impossible to cover all types of carburetors produced by gas trimmer manufacturers. But, since the design of this module, as well as its operating principle, is largely similar between different models, it is possible to make a generalized description of the processes occurring in the carburetor. This information will allow the user to understand the principles of operation of the device, troubleshoot problems and operate it correctly.

The basis of the trimmer carburetor is a solid aluminum body. Below is a diagram of this block.

At the bottom there is a diffuser, which is also called a Venturi nozzle (18). Air is sucked through this nozzle by a motor.

The smaller this hole is, the faster the air flows, and the higher the level of its rarefaction will be in the area with the smallest diameter.

In the upper part of the diffuser there are fuel channels (11,12). Air flows through these channels and draws in gasoline. The fuel pump itself, the jets and the system used to regulate the flow of the fuel-air mixture can be built-in or installed externally.

The throttle valve (9) regulates the amount of air drawn into the carburetor . Its amount affects the power that the engine develops. The flap (7) is used for cold starting. It must be closed if you are going to start the unit. After the engine has started, it must be opened, otherwise the engine will immediately stall.

READ What kind of oil can be poured into a petrol trimmer

The impulse channel (1) connects the impulse chamber of the pump with the engine crankcase, namely, with its internal volume. The piston located in the cylinder, performing reciprocating movements, consistently changes the pressure in the crankcase (vacuum or increase in pressure). Pressure differences 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 the membrane (4). Gasoline enters the carburetor through fitting (2). Further, its path lies through the inlet valve (3), exhaust valve (5), through the mesh filter (6), fuel channel (10), passes the needle (14) and fills the chamber (16), which has a control membrane (18) .

The valve (14) is connected to the membrane (18) via a lever (17). The cavity, which is located below the membrane, is connected to 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 leaks. 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 is mixed with the flowing air. Gasoline, mixing with air, begins to atomize. This creates an air-fuel mixture.
The finished mixture enters the cylinder, where it is compressed by a rising piston and ignites at its top point from a spark generated by the spark plugs.
Since the volume under the control membrane (18) is connected to atmospheric air through the channel (19), the membrane goes up, opening the valve (14) through the lever (17). After opening the valve (14), a new portion of fuel enters the chamber (16).
Once the chamber (16) is filled, the membrane (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 adjust the idle speed. When the regulators are unscrewed, the fuel mixture becomes richer, and when the regulators are tightened, the mixture becomes leaner. Also, in some carburetor models, you can adjust the engine idle speed using a quantity regulator. It is usually located on the outside and, when tightened, rests against a lever mounted on the throttle valve axis.

Thus, using 3 adjusting screws, you can achieve maximum engine performance, as well as configure its uninterrupted operation at any ambient temperature, and even in mountainous areas.

How does a lawn mower carburetor work or its operating principle?

Adjusting the carburetor of a Chinese lawn mower is completely identical to the adjustment of lawn mowers from European, Russian and other manufacturers. To cope with the task of adjusting the carburetor on lawn mowers and gas trimmers, you need to understand the principle of their operation. How a carburetor on a lawn mower is described step by step and in an accessible manner below.

The operation of the lawn mower begins with the supply of fuel through the channel, as shown in the diagram
Fuel is sucked into the carburetor using a pulse channel connected to the engine crankcase. Due to rarefaction of air, the flexible membrane at number 4 in the diagram above moves
Fuel is supplied through valves 3 and 5. Valve 3 is an inlet valve, due to which fuel is supplied to the sub-membrane space, and valve 5 is an outlet valve
Next, the fuel moves along the channel and, passing through a fine filter, reaches the needle valve 14
The needle valve is connected via a lever to the control diaphragm 18
The needle valve is activated by pressure on the membrane. When it is necessary to pump up fuel to start the engine, it is necessary to operate the soft cover of the hand pump. When exposed, the needle opens and the chamber is filled with the fuel mixture
When the engine starts (cold), the needle opens due to vacuum when the air damper is closed. This vacuum acts through the idle and high speed jets on the membrane 18
The membrane acts through a lever on the needle valve, thereby filling the chamber
After starting the engine, the air damper opens, causing the engine to run lean as fuel mixes with air.
When the chamber is full, the fuel mixture is supplied (sucked in) through the idle and medium speed jets (when the engine is running)
The throttle valve is shifted from its original position by 10-15 degrees
When work is carried out under load, fuel begins to flow into the chamber through the high-speed nozzle, and at the same time the throttle valve rotates at an angle of up to 90 degrees (depending on the force of pressing the gas). In all operating modes, the air damper must be open, through which the fuel is mixed with air, thereby igniting the mixture in the cylinder

READ How to sharpen a lawn mower blade correctly

Below is a diagram of the operating principle of a lawn mower . Based on the diagram, you can not only understand the principle of operation, but also identify breakdowns and other malfunctions of the mechanism.

When operating the tool, it is necessary to take into account the presence of another jet. This jet is located between the idle and full power passages. It is necessary in order to avoid severe leaning of the mixture, which occurs when the engine operates at partial load. In such a situation, the occurrence of a bullying couple cannot be ruled out. Through an additional channel (nozzle), fuel is sucked into the chamber, thereby enriching the fuel-air mixture. The diagram below shows an additional jet, which is designated by the number 1.

Having an idea of the design of the diaphragm carburetor of a brush cutter and the principle of operation, it will not be difficult to configure it yourself. To adjust the carburetor of a lawn mower, adjusting screws are used. The diagram above shows two screws for adjustment, however, most modern models of gasoline trimmers are equipped with three screws. The presence of three adjustment screws allows for more precise adjustment, while achieving stable and uninterrupted operation of the internal combustion engine.

This is interesting! What is the difference between a trimmer and a lawn mower? Many people think that trimmers are low-power electric lawn mowers. However, trimmer is a generic name for gas trimmers, walk-behind trimmers and electric mowers as they are designed for a common purpose.

Adjusting the carburetor of the STIHL FS 55 brushcutter

Adjusting the carburetor of the STIHL FS 55 brush cutter Sadservis spare parts store sadservice.com.ua.

Fuel is sucked into the carburetor system by a pump (its membrane). Then it passes through the fitting in the carburetor. The liquid then moves through the inlet and outlet valves of the pump. Filtered with a mesh. It moves along the needle valve into the membrane chamber.

Blowing clogged carburetor parts with compressed air is an acceptable and convenient repair practice.

The throttle body, carburetor parts, intake or exhaust pipes - all of these parts are subject to depressurization. You can definitely check it in a primitive way - spread soap foam on the problem area.

The principle of operation of a lawn mower carburetor

The throttle valve determines the amount of air supplied, and the engine power directly depends on this.

Worn throttle and choke shaft

The air and throttle valve shaft may wear out due to 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 the entry of poorly purified 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 (functional) one. The filter must be washed in soapy water and dried.

Signs of imbalance

The carburetor must be debugged during the manufacture of the device. As a rule, owners learn about the need to adjust the fuel supply with their own hands only after quite serious breakdowns, during the process of correcting which the module was removed and, for example, cleaned.

Signs of a settings failure include the following:

starts, but the engine immediately stalls - since the engine can only work when a certain amount of gasoline is supplied, if the fuel is too “lean”, that is, the supply channel is blocked, the engine will stop;
too much fuel consumption, a lot of exhaust gases - the result of incomplete combustion of the mixture. In this case, on the contrary, there is too much fuel and the mixture turns out to be excessively dense.

The carburetor of STIHL, Makita, Husqvarna and other lawnmowers is adjusted using adjusting screws. Sometimes the cause of malfunction is a violation of fixation - due to vibration or damage to the protective cap. Such a breakdown can be detected by simply trying to slightly turn the screw: if the fixation is not tight, it is worth checking the setting.

Principle of operation

Carburetor is a power system module in which liquid fuel and air are mixed before being supplied to the engine cylinders. Depending on the tool and its operating mode, mixing and feeding are adjusted accordingly.

The structure of the lawn mower carburetor is the same in almost all cases. It belongs to the category of float devices. The latter provide stable parameters for the finished mixtures.

Air enters the body of the tube with an air damper. The latter increases or decreases the air flow depending on its position.
In the area where the hole for supplying gasoline is formed, the tube has a narrowing - a diffuser. Here the flow speed increases.
Fuel from the float chamber is supplied through a nozzle into the tube. The float level determines the amount of fuel supplied. Since the pressure in the chamber is normal, and in the tube it is low due to the greater rarefaction of the air, gasoline is sucked in through the nozzle.
The accelerated air flow picks up the fuel and atomizes it, forming an air-fuel mixture of the desired density.
The mixture is sucked into the cylinder through a pipeline.

The more open the air damper in the tube, the higher the air flow density, which means more fuel enters the cylinder. Setting up the carburetor of a lawn mower comes down to setting the valve ratio at which the density of the fuel mixture becomes optimal.

Do-it-yourself trimmer carburetor adjustment

Setting up the module is not a repair and replacement of spare parts is not required. In this case, the lawnmower carburetor repair kit will not be needed.

L – is regulated first, since it is responsible for fuel supply at low speeds;
H – it is responsible for the supply of gasoline at high speeds, as well as fuel consumption and temperature;
T – it is used to debug the idle speed.

There are options, as a rule, this is the carburetor of a Chinese lawn mower, when for debugging there is only one screw left on the body - for adjusting the idle speed. This does not mean that the module is configured automatically - it means that even such a type of repair as debugging will be difficult. The photo shows the adjustment of the carburetor of a Chinese lawn mower.

The module is configured only when the engine is warm: to do this, the device is first turned on for 10 minutes. If the mowing head rotates at idle, then begin debugging immediately: turn screw T counterclockwise until rotation stops.
The adjustment begins with screw L. The screw is turned to the right and left until a position is found at which the idle speed does not become maximum.
Then the screw is turned ¼ turn counterclockwise. This will be his working position.
The idle speed must be adjusted by turning counterclockwise to increase the speed and clockwise to decrease it. Its debugging consists in achieving a mode in which a sufficient number of revolutions are made before the mowing head begins to rotate. In this case, the engine must operate stably in different positions.
The position of screw L is determined last - at maximum speed the trimmer should not operate for more than 10 seconds. The throttle opens, the screw is turned clockwise, very slowly, until a decrease in the number of revolutions is heard by ear.
Then the screw rotates slowly counterclockwise until the motor begins to malfunction. After which the screw is turned back clockwise until the engine starts working normally again.

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If there is a tanometer, and if the recommended speed values are indicated in the product data sheet, the correction can be carried out more accurately, focusing not on hearing, but on the readings of the device.

The trimmer carburetor adjustment in the video was done by ear.

to the entry “Adjusting and repairing the carburetor of lawn mowers”

Please clarify. In the adjustment section, item 5, is screw L an error? Should you read screw A? Thank you.

tell me the initial position of the HL LA screws

Thank you very much for the video about the accelerator, I didn’t know that the defect is very important and creates a huge problem that almost everyone is silent about. BRAVO….

Maybe the tachometer is a speed meter, and not a tonometer, a blood pressure meter

In the video he’s kind of slow-witted, so you have to know how to chew snot.

Trimmer adjustment screws.

Regardless of the trimmer manufacturer, each trimmer has three adjustment screws (in very rare cases two) that adjust the carburetor. Let's look at the types of adjustments using the example of the professional STIHL fs 450 hedge trimmer.

This trimmer has three adjustment screws:

Upper left screw (H) - regulates the amount of fuel supply at high speeds;
Upper right screw (L) - regulates the amount of fuel supply at low speeds (idling);
Lower left screw (LA) - adjusts the idle speed, this screw can also be designated by the letter T;

Features and best models

The mower deserves special mention, notable for its versatility, reliability and ease of operation. The company's specialists have developed many types of braids, with different characteristics and applications.

For example, the range of lawn mowers is designed for mowing grass over large spaces . For this purpose, a self-propelled wheeled system was developed, with the help of which it became possible to care for a large area without spending a lot of time and effort. A brush cutter is perfect for decorating shrubs, giving them some artistic image and texture. And if you need a lawn mower for tall grass and uneven areas, then follow this link and get complete information on selecting this type of equipment.

If you need a more subtle approach to grass cleaning, for example, around flower beds or between trees, then a gasoline trimmer, designed for accuracy and precision, will do the job perfectly. The company's specialists took into account all the nuances and possible difficulties when working with scythes, so they equipped them with nylon strings, which prevent mechanical damage to trees.

A special AutoCut trimmer head is also used, which ensures the normal functionality of the gas trimmer string knives. This article will tell you about the prices for gasoline manual lawn mowers and trimmers, and it will also help you make the right purchase, which you will not regret.

There are two types of these mowers: amateur and professional models, designed to solve problems of a certain complexity. The first category includes models FS 38, FS 45, FS 55, etc. The features and differences of these tools are the motor power (from 0.9 to 1.2 hp depending on the configuration) and tank volume (approximately 0. 34 l).

Professional trimmers include Stihl FS 130 and FS 250. Let's look at the characteristics and properties using the example of several mowers, in particular FS 38, FS 70 and FS 130.

Watch the features of the device in the video.

Petrol lawn mower FS 38

The model is distinguished primarily by its simplicity and compactness, which is quite enough for proper care of the local area. The main control keys are located on the handle of the device, which greatly facilitates and speeds up work.

The price for the Stihl FS 38 mower is about $130.

engine power – 0.9 hp;
engine capacity – 27.2 cm3;
tank volume – 0.33 l;
engine type – two-stroke;
bar – straight;
handle – D-shaped;
equipment - 2-tooth grass trimmer blade, protective glasses, belt;
weight – 4.1 kg.

This model is one of the most popular on the market! You will learn about all the units that are included in the rating of the best gas mowers here.

Price mower Shtil FS 70

It is a more advanced model, characterized by higher power and multitasking . An anti-vibration system is provided to significantly reduce the impact of a running engine on the handle.

The new generation engine reduces fuel consumption. The cost of this model varies, but the average price is about $300.

Characteristics of FS 70:

engine power – 1.2 hp;
engine volume – 27.2 cm3;
tank volume – 0.34 l;
engine type – two-stroke;
bar – straight;
handle – T-shaped;
complete set - belt, reel with fishing line;
line diameter – 2.4 mm;
weight – 5.4 kg.

FS 130

The model is a professional model, so the goals set for him will be a little higher. It is designed for mowing coarse grass, cleaning tough bushes and young trees.

It features the latest high-power engine that does not emit large amounts of harmful emissions.

The price for the Stihl FS 130 mower is about $400.

engine power – 1.9 hp;
engine volume – 36.3 cm3;
tank volume – 0.53 l;
bar – straight;
handle – T-shaped;
equipment - shoulder strap, two-blade knife;
line diameter – 2.4 mm;
weight – 5.9 kg.

The range of prices for these models does not indicate any difference in quality; first of all, each Shtil mower is designed for a specific type of work.

It is clear that there is no point in purchasing a more expensive and powerful model if you have a small plot or front lawn. Simpler models will cope with this task perfectly, but the word “simplicity” is not used here in a derogatory manner. More powerful mowers are designed to handle larger areas with overgrown and dense surfaces, hence the price difference. If you are confused by such a variety of tools, then do not be upset, but feel free to click here and we will tell you how to choose a lawn mower for your dacha.

Adjusting the trimmer yourself.

Adjusting the trimmer carburetor.

Adjustment of the trimmer (mower) should be carried out in accordance with the technical data sheet. The most correct thing to do is to read the information in the instructions for your trimmer. It usually describes in detail how to adjust the lawn mower. If you do not have instructions for the trimmer, then you can use our advice.

Steps for adjusting the carburetor of a lawn mower:

Correction of fuel supply at low speed L;
correction of the idle speed using the LA (T) screw;
adjusting fuel supply at high speeds - H.

STIHL FS 55. carburetor adjustment (idle speed)

Trim adjustment. Service. Introduction.

Over the course of its life, the grass trimmer requires maintenance. It is important to monitor the condition of the air and fuel filters, as well as the spark plugs. However, even with conscientious use of lawn mowers, problems may arise. One of the possible problems may be misalignment of the trimmer . As a rule, this problem arises from vibration or foreign interference in the adjusting screws of the lawn mower. Today in this article we will look at how to properly adjust the trimmer and what main points you should pay attention to.

Adjusting the fuel supply at high speeds - H.

The third stage, adjusting the fuel supply at high speeds - H. For STIHL trimmers, unscrew the screw all the way counterclockwise, then turn it a quarter clockwise. In general cases, the adjustment of trimmers from other manufacturers is almost the same. The screw is unscrewed completely counterclockwise, then the lawn mower is started and full throttle is squeezed out. Then turning the screw clockwise (usually 1/4, 2/4 turn) reduces the maximum speed by about 5-10%. Thus, the adjustment of the lawn mower is completed. When adjusting the carburetor with this screw, turning clockwise reduces the fuel supply, turning counterclockwise increases it.

Adjusting the idle speed using the LA (T) screw.

The second stage of adjustment is adjusting the idle speed using the LA (T) screw; here the setting is made solely by ear. By turning the screw clockwise, you increase the speed; by turning it counterclockwise, you decrease the speed. It is important to ensure that the mower head does not rotate at idle speed. It should also be noted that screws L and LA are adjusted in pairs, that is, changing the adjustments on one screw may require changing the adjustments on the second. After you have achieved smooth engine operation with a minimum of vibrations, proceed to adjusting H.

Tools

Petrol trimmer/petrol scythe STIHL FS 55 is a lightweight, mobile scythe with a large power reserve. An indispensable assistant for mowing meadow and ornamental grass vegetation, when mowing on wavy or rugged terrain. With equal productivity, the unit polishes soft grass and clears dense thickets of bushes or overgrown grass. A small bar allows you to mow in hard-to-reach places: along the wall of the house, around bushes, poles, benches.

READ How to Clean the Carburetor on a Chainsaw

Running in the STIHL FS 55 petrol trimmer/petrol mower. Instructions for users

Running in the trimmer is necessary for subsequent normal and long-term operation. During running-in, the moving parts are ground in, the initial resistance in the drive mechanism is increased; to reduce it, the parts are slightly “weared out”. The break-in process also gives a beginner the opportunity to learn how to operate the trimmer.

Before starting work, prepare a fuel mixture from the recommended brands of oil and gasoline indicated in the data sheet. The proportions are approximately as follows: for 2.5 liters of AI.95 add 100 grams of STIHL oil in red packaging. For mixing, purchase a container made of plastic that is resistant to aggressive liquids or an aluminum tank. An ordinary canister always has rusty micro-areas; when rust accumulates in the saw’s carburetor, it leads to clogging and breakdown of the unit.
The total operating time during running-in is from 3 to 4 hours. During this period, it is not recommended to operate the tool at idle speed for more than 15 minutes. A constant boost of gas is required for 20-30 seconds.
It is possible to combine running-in and performing simple work without load, for example, mowing soft vegetation.
Once every six months, a tool with a warranty period must be brought to the service center for technical inspection and carburetor adjustment.

The structure of a lawn mower carburetor

The basis of the lawn mower carburetor is an aluminum body. It contains a diffuser (a hole with internal contours). Air is forced through this hole. The oxygen (air) supply rate depends on the cross-section (pass hole) of the diffuser.

How to independently adjust a carburetor with three adjusting screws: full cycle

The diffuser is equipped with fuel channels. Fuel is drawn from them using an air flow.

fuel pump;
jet system;
system for adjusting the fuel-air mixture;

The principle of operation of a lawn mower carburetor

The throttle valve determines the amount of air supplied, and engine power directly depends on this.

Air supply into a tube with an air baffle (damper). The partition regulates the intensity of the air flow.
The fuel supply system is necessarily narrowed with a diffuser to increase the flow rate.
Gasoline through the float chamber and the nozzle tube with a narrowing. A chamber with a float regulates the temporary volume of gasoline. In the float chamber the pressure level is neutral, and in the tube with a narrowing it is already low. Due to the pressure difference, fuel penetrates through the nozzle.
Accelerating air flow promotes the transfer of fuel (gasoline) and its atomization. As a result, an air-fuel mixture of the required proportion or density is formed.
The air-fuel mixture enters the engine cylinder through the fuel pipe.

The level of air density in the system depends on the area of the open air damper. The wider the throttle is open, the greater the fuel consumption and power.

Simply put, adjusting the carburetor on a lawn mower is creating an optimal fuel mixture due to the correct air supply.

Pros and cons of the model:

Excellent performance;
Compactness;
Light weight;
Functionality;
Endurance;
Ability to independently adjust the operation of elements;
Availability of a manual fuel pump;
D-handle, etc.

Naturally, the list of positive aspects should include the reliability of the brand itself.

The need to constantly check the fuel level;
Small motor resource;
Low power;
Expensive;
Poor equipment.

The presence of not particularly catastrophic shortcomings of the model does not have a negative impact on the popularity of the unit, because ideal technology simply does not exist.

Main problems and malfunctions of the carburetor.

Mesh filter. There are usually only two problems with this element:

In order to find out the cause of the breakdown, unscrew the fuel filter cap to remove the strainer. If dirt has simply accumulated on it, then washing it in gasoline or blowing it out will help.

READ How to dilute trimmer mixture

If there is visible damage to the mesh filter, be sure to install a new one. There may also be damage to the fuel supply pipe (during repairs, it is practiced to check this element).

Blowing clogged carburetor parts with compressed air is an acceptable and convenient repair practice.

Repair instructions

The STIHL FS 55 petrol mower, the operating instructions for which are supplied and must be studied by you before starting work, is a high-tech equipment that is not difficult to maintain. You can carry out repairs and adjustments yourself. As for the carburetor, this is a matter of 5 minutes.

The main problems of carburetor malfunction can be breakdowns and blockages. In order to find out the reason, you should unscrew the fuel filter cap and remove the strainer. If dirt has accumulated on it, then blowing or washing in gasoline will help. If you find visible changes on the filter, it should be replaced with a new one.

READ What Oil to Use in a Champion Lawn Mower Engine

The fuel supply pipes may also be damaged. Failure to operate the carburetor starter may occur due to gaps. Gasoline or acetone is used for washing. The carburetor can be blown out with compressed air using a convenient repair practice. The exhaust or intake pipeline may become depressurized, as well as the throttle body and those places where the carburetor parts are connected to each other. If you encounter the above-mentioned problem, you can verify it using a soap solution that is applied to the desired area.

How to adjust the carburetor on a lawn mower

Before adjustment, the filters must be thoroughly cleaned according to the maintenance instructions.

Further adjustment of the lawn mower carburetor is done with your own hands using adjusting screws. There are three in total:

right;
left;
lower.

Right (L) – adjusting the fuel mixture for low speeds.

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 turn counterclockwise.

Lower (T) – is responsible for adjusting the engine at idle.

clockwise – increase;
counterclockwise – decrease.

For correct adjustment of idle speed it is typical:

stable operation of a cold engine;
not over-revving a hot engine;
there is a large reserve of revolutions for the trimmer head;
stable operation of the engine when changing position (sharp raising or lowering of the knife).

Left (H) – mixture adjustment at high speeds. (The screw is adjusted last).

The overall adjustment of maximum speed, engine power, temperature and gasoline consumption depends on the left screw (H).

Setting up the carburetor of a lawn mower with the last screw is done as follows:

Open the throttle to full, while releasing full throttle. Turn the screw clockwise until the speed drops (in this case, use your ear).
Turn the screw as slowly as possible counterclockwise until the engine runs rough.
Then turn back just a little, barely hearing stable, smooth operation.
For a more visual application of skills, it is more convenient to consider the work of an experienced user:

It is interesting that from the point of view of the author of the video, the setting (its correctness) is determined by the color of the spark plug, and not just by the engine speed and stability.

Correctly adjusting the carburetor with your own hands in this case means combustion of the fuel mixture without residue; the color of the spark plug should be light brown.

The principle of operation of a lawn mower carburetor

The principle of operation of a device such as a carburetor is to combine liquid fuel and air before feeding this mixture into the engine cylinder. It is a module of the power system of any unit that has a motor, and is “responsible” for the mixture parameters. First:

air passes through a tube with an air damper;
the air damper can increase or decrease the air flow, depending on its location;
the narrowing of the tube just before the entrance to the hole where gasoline is supplied is called a diffuser, at this point the air flow becomes more intense;
the tube receives fuel through a jet from the float chamber (some Chinese models do not have it). The float determines the level of the amount of fuel that is supplied. Through the nozzle, gasoline passes into the tube, since there is low pressure in it (rarefied air), and in the float chamber it is normal.
when air passes through the diffuser at high speed and “meets” the fuel, it seems to atomize it, creating the necessary consistency of the air-fuel mixture.
it is then sucked through the pipeline into the engine cylinder.

The carburetor of a lawn mower is a fairly popular topic on the Internet, since many users want to understand the specifics of its operation in order to be able to independently correct problems in the operation of the mechanism. Is such work with the carburetor worth the trouble? the concept is relative, since when its individual parts are deformed, or even more so! When cleaning the channels with a needle and wire, you can damage the elements of the lawn mower or completely negate the trimmer’s .

It is important to understand that a gasoline scythe is not a toy in the hands of even an experienced instrument specialist, and it is better to repair the carb yourself after thoroughly familiarizing yourself with the instructions, following the video type and having practice under your belt. To maintain the durability of the carburetor, you should use high-quality gasoline, do not overheat the device, clean the air damper on time and change the air filter.

We will show you how to properly inspect any part of the scythe and select the necessary spare part: from such an important component as a spool of line for a trimmer to the global carburetor mechanism.

Why do you need to adjust the carburetor 55

Working with petrol trimmers of the series foreshadows their active use, since the performance of this unit is not limited to leveling lawns. As a result, miscalculations appear in the operation of the engine, and adjustment of the carburetor 55 with simple manipulations is required. The failures that occur are unpleasant and promise incomplete work or waste of fuel consumed in large quantities. You should think about adjusting the trimmer carburetor in cases where:

There are inexplicable engine stops after starting it;
During operation, the engine of the 250 series scythe, through an untuned mixture supply mechanism, “sobs” under load.
The work is accompanied by an increased amount of gas exhaust.

In any case, each of the reasons lies in the mixing of air and gasoline, where performing a carburetor adjustment on the 130 will avoid unexpected engine stops in the middle of operation. The system of the professional gasoline scythe 130 with a rigid drive shaft ensures fast cutting of wood, which will shut down the engine if there is a lack of air in the fuel. On the other hand, a tuned mixer 38 line or trimmer model line 450 will allow you to avoid spitting out gasoline under applied loads, when there is often a lack of air in the carburetor. You can purchase all components for motor trimmers, find out information about setup, and also buy a spark plug wrench and other spare parts for successful repairs.

Checking the correct adjustment of the brush cutter carburetor

So, guided by all the requirements and technical recommendations, the mower’s carburetor is adjusted to improve its performance. The process of checking the results obtained begins from the very first steps, when, while the lawn mower engine is idling, the screws are manipulated to adjust the fuel mixer. For example, if after controlling the low-power screw the malfunctions stop, the maximum speed screw need not be disturbed. To convince, it is enough to turn the latter forward, where the presence of failures, instead of an increase in power, will show that the mechanism has been adjusted, and it is worth returning the screw to its original position.

Also, a properly tuned 55 Series mower will show that the applied load does not affect performance. The process of diagnosing a self-made adjustment of the carburetor mechanism will be accompanied by:

No failures when rotating the screws.
No failures during idling even when the position of the tool changes;
No symptoms at full workload.

Here you should perform the gas trimmer test carefully, increasing the load from small portions to the maximum permissible processing object. Also, in order to prevent other problems, Kosa-Motors recommends timely inspection of the mower, for which you should arm yourself with knowledge, as well as order lubricant for the gearbox and other components and mechanisms for long-term and productive operation of the device.

Carburetor design for brush cutters made in China

Today, a relevant and open question is that it is briefly formulated as follows: The carburetor of a lawn mower is a device. And if European and American-made professional lawn mowers contain information about carburetor settings in their instructions, then the diagram of this element of a Chinese-made scythe is not yet available to a wide range of users. In this article we will try to figure out what is special about the carburetor of a lawn mower, the country of manufacture of which is China, and how it differs from those, for example, that are found on the original Husqvarna, Shtilah and, for example, Oleo-Mac, which were not produced in China, but purely in Italy.

Optimally, this unit will be described by individual elements, and here we will indicate the difference from other types of carburetors of this instance:

Diaphragm type fuel pump.
Regulating system with atmospheric membrane.
Idle system.
Dosing system with quality screw.
Primer (popularly “pumping”) - helps to exhaust all the fuel from the tank, and also makes it easier to start if you have not used the tool for a long time.
The main part is an elastic plate of complex shape, it contains two valves.
The needle valve is similar to a car valve - this is the adjustment system. When the pressure decreases, it closes with a special membrane. In the first photo there is the second connector from the case, on the left.
The dosing system is of a rotary type, where the latter rotates.
The air damper in this type of carburetor forms part of the air filter.
The quality screw is located on the right in the center of the rotor, it is sealable.
Idle system

Features of the STIHL lawn mower carburetor

The carburetor design of the brush cutter produced by the German company STIHL differs from the Chinese similar mechanism in that it requires manual adjustment by the user. For this purpose, screws L, H, T are installed here. If the protective cap of the brush cutter is damaged, they can unscrew and then the work will become disordered. The problem can be quickly resolved by returning a certain screw to its previous position. The same situation occurs from excessive vibrations of the entire gas trimmer apparatus. On the carb of a Chinese mower, as a rule, there is only one screw - for regulating the idle speed.

Almost any correction to the operation of the STIHL FS 55 scythe carburetor can be carried out independently, using your hearing or a special device - a tanometer. The check should only be carried out after the engine has warmed up. From this educational video you will learn useful information about the carburetor. To ensure productive operation of the scythe mechanism, we will always offer high-quality but cheap oil for the compressor, as well as any other accessories and spare parts.

Sources:

https://fermerteh.ru/remont-karbyuratora-benzokosy https://domamaster.net/regulirovka-trimmera-svoimi-rukami/ https://glav-dacha.ru/regulirovku-karbyuratora-benzokosy/ https://www .kosikosa.com/index.php?route=information/news/infonews_id=39