How to adjust the rpm on the trimmer

Malfunction of the fuel pump

The most repetitive breakdown is wear and tear of the diaphragm. As a result, its non-conformity. The fuel passages are not sealed at certain stages in the engine cycle. The reasons are as follows:

  • You have been working on the lawn mower or trimmer for too long without interruption.
  • fueled with low-quality fuel;
  • exhaust gases enter the impulse channel.

adjust, trimmer

A deformed membrane is fraught with several bad consequences:

  • there is not enough gasoline or oxygen in the generated combustible mixture;
  • the motor starts after 10 or more unsuccessful attempts;
  • the engine knocks, clinks during operation, etc.;
  • the working piston is deformed.

As a result, the inner space of the fuel pump is contaminated from the side of the impulse channel.

Spring may interfere

My first attempt to adjust the carburetor of the lawn mowers did not work, as the spring of the screw for adjusting the fuel mixture interfered with. The factory spring turned out to be too thick in the compressed state and did not make it possible to reduce the fuel supply to the required level. I had to pick up another spring and continue adjusting after replacing it.

Fuel mixture adjusting screw with spring

In the photo above the factory spring, below the adjusting screw with the matched spring. I am writing about this because I’m not sure if this is an isolated case, and someone else may face the same situation.

lawn mower or trimmer

A trimmer is a broader concept than a lawn mower (lawn mower), as it can also be electric. A petrol trimmer and a lawn mower are one and the same.

Some authors claim that the trimmer is a weaker tool than a more powerful lawn mower, which can be used for mowing shrubs. Personally, I have a tool with a maximum power of 1.7 kW and capable, as stated in the instructions, to mow small shrubs up to 10 mm thick. The user’s manual is called “Petrol trimmer. “.

Strainer clogged

Reasons for blockage of the mesh filter. poor quality fuel cleaning, damage to the hose and / or delivery head.

Failure of the adjusting lever

The wear of the contact edge of the lever is a consequence of an incompletely purified fuel, into which grains of sand or particles of clay, metal or other inclusions that are not soluble in liquid hydrocarbons have gotten. There is a problem with fuel injection, the engine does not function without load.

The main problems and malfunctions of the carburetor.

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

  • Blockage.
  • Breaking.

In order to find out the cause of the breakdown, the fuel filter cap is unscrewed to remove the strainer. If dirt just accumulates on it, then flushing in gasoline or blowing 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 repair, they practice checking this element).

The carburetor starter in most cases does not function due to blockages. Use acetone or the same gasoline for flushing.

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

The throttle body, the places where the carburetor parts are bundled, the inlet or outlet pipe. all of these parts are susceptible to depressurization. You can check for sure in a primitive way. smear the problem area with soapy foam.

Idle speed adjustment

We start adjusting low speed. The screw limits the return movement of the throttle lever. by turning it, we increase the idle speed, unscrewing it, we decrease it. Adjust so that the engine runs confidently at low revs and even slightly accelerated (for better starting), but so that the line reel or knife does not rotate, and there is a sufficient reserve of revolutions before they start spinning. If the engine starts poorly, increase the idle speed even more.

Trimmer carburetor. How to properly adjust the trimmer carburetor.

On trimmers, in addition to electric motors, gasoline internal combustion engines are installed. This mechanism requires special attention to itself, since if it is incorrectly configured, it will either refuse to work, or it will work intermittently and loss of power. Basically, engine tuning is about adjusting the fuel flow, and this is done using the carburetor trimmer.

The standard design of any gasoline trimmer necessarily includes a fuel system, the basis of which is the action of a regular carburetor. Its structure and initial principle of operation are almost the same for all lawn mowers, regardless of their design features and purpose.

The lawn mowers carburetor consists of an all-metal aluminum housing that protects the internal components of the unit from moisture, small debris and dust. In the lower part of the body there is a built-in diffuser, the second name of which is “Venturi nozzle”. The main function of this standard part is to supply air in the amount required by the fuel unit to enrich the fuel. A diffuser works according to a simple principle: the smaller its diameter becomes, the more intensively the air is sucked in. This is due to the fact that in the area of ​​the smallest diameter, the level of air vacuum becomes maximum.

The upper part of the built-in factory diffuser is pre-equipped with fuel pipes, through which, under the influence of air, the fuel mixture is drawn in. The rest of the carburetor parts: standard adjusting screws and a fuel pump, can be located both inside and outside the carburetor.

The device of the carburetor of lawn mowers includes a throttle valve, the main task of which is to regulate the volume of intake air. The larger the amount of air, the higher the rated power of the trimmer power unit. Another function of the damper is to facilitate cold starting of the engine. If this is the first time the mower is started after a long period of inactivity, the shutter must be closed. Immediately after starting the engine, the part must be opened, otherwise the internal combustion engine will stall.

The carburetor for the trimmer is equipped with an impulse channel that connects the internal cavity of the engine crankcase with the impulse chamber of the pump. The piston located in the engine cylinder creates reciprocating movements, which leads to gradual changes in pressure inside the crankcase. At the same time, the membrane is set in motion. Thus, the action of the pump is fully synchronized with the operation of the power unit.

The diaphragm of the standard carburetor takes an active part in the suction of fuel. It enters the fuel unit through the fitting. The fuel then passes through the integrated inlet and outlet valves, then through the strainer and fuel pipe. The fuel then flows next to the needle and gradually fills the chamber equipped with the control diaphragm.

The standard carburetor trim valve is connected to the diaphragm using a lever. Below the built-in membrane there is a cavity into which air is sucked in through a special opening.

The lawn mower carburetor works on this principle in stages. This ensures continuous operation of the fuel unit and uninterrupted fuel supply to the cylinder of the standard power unit.

When is the carburetor setting of the household trimmer required? Adjust the built-in trimmer carburetor when:

  • running in a new engine, during which from 4 to 5 liters of fuel mixture were used;
  • sudden changes in weather;
  • changes in air pressure. for example, when the lawn mower is often used in mountainous areas;
  • long-term simple trimmer;
  • intensive growth of loads on the power unit of lawn mowers;
  • arbitrary unscrewing of the built-in adjusting screws of the carburetor. this causes increased vibration of the internal combustion engine;
  • changes in the quality of the components of the fuel mixture;
  • pouring fuel with a carburetor, resulting in an increase in fuel consumption;
  • the regular appearance of a thick layer of resinous deposits and carbon deposits on the surface of the electrodes of a standard trimmer spark plug;
  • starting the engine and its arbitrary shutdown or a slow set of revolutions;
  • lack of fuel flow into the cylinder of the power unit;
  • an increase in the volume of emitted waste gases.

The lack of timely adjustment of the carburetor threatens with a serious breakdown of the trimmer, up to the complete failure of its factory engine.

Do-it-yourself lawn mowers carburetor adjustment. Periodic adjustment of the trimmer carburetor should be performed on a serviced and fully serviceable power unit. Before starting the procedure, the operator must thoroughly rinse the internal combustion engine parts and inspect its CPG for burrs or other defects. In addition, you will need to clean or change the spark plug, as well as rinse the filter elements in the lawn mowers structure.

The lawn mower engine must be running under a certain load when adjusting the carburetor. It is best to install a cord of the appropriate diameter or cutting knives on the trimmer.

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After installing the cutting elements, the operator should start the internal combustion engine of the trimmer and leave it to work for about 10 minutes. If, during the operation of the power unit at idle, it was noticed that the cord or knife rotated, then it is necessary to reduce the speed generated by the motor. To do this, turn the lower adjuster, often marked with the letter “T”, to the left, until the installed cutter comes to a complete stop. Further configuration of the fuel assembly is as follows:

  • The “L” regulator, located on the right, is responsible for enriching the fuel mixture with air when the engine is running at low revs. The position of this screw must be adjusted first. To do this, the operator will need to achieve maximum engine speed when idling. to do this, turn the screw “L” one by one to the right or left. As soon as the maximum speed is reached, the screw will need to be turned 1/2 turn to the left;
  • The screw “T” or “LA” is required to adjust the idle speed. While turning it to the left, the speed of the power unit will decrease, and when turning to the right, accordingly, it will increase;
  • The regulator “H”, provided on the left, is responsible for enriching the fuel mixture with air when the internal combustion engine trimmer is running at high rpm. This screw is also needed to adjust the engine power and the amount of fuel consumed. Its position is adjusted by turning the screw to the right or left side until the maximum permissible engine speed is reached. After that, the screw “H” will need to be turned 1/2 turn to the left.

Common carburetor malfunctions. Failure of the trimmer carburetor occurs due to the use of poor quality gasoline, a damaged air filter and the accumulation of dirt in the chamber of this unit. Most often, it is quite possible to repair the carburetor with your own hands. Listed below are typical lawn mowers carburetor malfunctions.

Fuel pump problems. A common malfunction that “pursues” the fuel pump is the deformation of the pump membrane. For this reason, it does not fit properly and the pump passages are not sealed.

The reasons for membrane deformation can be the following:

  • long work of the trimmer;
  • use of unsuitable fuel;
  • ingress of gases into the impulse channel.

As a result, diaphragm damage reduces pump performance and, as a result:

  • depletion of the combustible mixture occurs;
  • it is difficult to start the engine;
  • there are interruptions in the operation of the motor;
  • the piston is damaged.

Also, the above-described consequences for the engine can cause clogging of the pump cavity on the impulse side. In this case, dirt enters the membrane through the impulse channel.

To remove the blockage, you will have to disassemble the carburetor and clean the membrane.

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Clogged strainer
The strainer can become dirty if contaminated fuel enters through a fuel hose or defective pickup head. In the photo below you can see what a clean filter looks like and a dirty one (parts are separated by a line).

Correcting the malfunction will require thorough cleaning and rinsing of the strainer. It is also recommended to blow compressed air through all holes in the carburetor trimmer housing.

Adjustment lever defective
This breakage occurs when the contact surface of the lever wears out.

The abrasion of the contact surface occurs due to the presence of abrasive particles in the gasoline or due to strong vibration of the engine during operation. This defect in the adjusting lever causes problems with the intake, as well as improper idling of the engine.

Intake needle wear
The inlet needle fails, as a rule, due to the presence of abrasive particles in the fuel fluid.

  • the tightness of the inlet needle seat is disrupted;
  • there is a leakage of a combustible mixture;
  • there are malfunctions in the engine operation associated with re-enrichment of the fuel mixture.

Also, the inlet needle may just jam.

A jammed inlet needle can cause dirt in the fuel or a long idle time.

Clogged control cavity
If dirt accumulates in the control cavity, then the inlet needle cannot tightly close the hole and a lot of fuel pours into the chamber.

This causes over-enrichment of the fuel and the engine starts to malfunction. It is necessary to disassemble the carburetor and clean the cavity of the control membrane.

Deformation of the control diaphragm
The membrane can undergo deformation during prolonged operation of the unit and when using aggressive fuels.

Failure of normal adjustment due to a defect leads to:

  • damage to the piston;
  • difficulties when starting up;
  • depletion of fuel;
  • improper engine operation.

Intake Adjustment Lever Problem
This problem can occur if the adjusting arm is not properly installed or if it is bent before installing. As a result, the contact surface takes the wrong position, which disrupts the additional fuel supply.

Damper wear
The throttle and choke valves are mainly subject to wear due to the presence of abrasive particles in the air. Defective dampers 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.

Throttle and choke shaft wear
The air 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 the ingress of poorly cleaned air, the shaft wears out and can 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 flush the existing (serviceable) one. The filter must be washed in soapy water and dried.

How to properly adjust
Before you start adjusting the carburetor trimmer, 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).

How to adjust the idle speed on your weed eater/poulan trimmer

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

If at idle speed of the engine you notice that the cutting tool rotates, then it is necessary to reduce the engine speed. This is done using the lower idle speed control, often marked with the letter “T”. 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 comes to a complete stop.

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

  • The right L regulator adjusts the enrichment level of the combustible mixture at low revs. It needs to be regulated first. Achieve maximum idle speed. This is done with the L knob by turning it left and right. After finding the point of maximum speed, return the regulator half a turn to the left (counter-clockwise).
  • The lower T (LA) adjuster is used to adjust the idle speed. 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 run at full speed for more than 10 seconds, then it may fail.

To eliminate this nuisance, adjustment will be required. With the engine running, give full throttle, then turn the regulator “H” to the right until the speed starts to decrease. After that, the regulator “H” must be slowly scrolled to the left until you hear the uneven operation of the engine. Then you should turn the knob “H” to the right until you hear the smooth operation of the motor.

After performing the above steps, the carburetor setting can be considered complete. After correct adjustment, the engine should confidently pick up speed, a little quarter at maximum speed, and when idling, the cutting tool should not turn. This manual is suitable for adjusting carburettors 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: an idle speed regulator and a fuel mixture quality regulator at high speeds.

Fuel supply adjustment

Start slowly tightening the fuel mixture adjustment screw until the engine starts to stall or stalls if you do not have time to catch the moment. After that, unscrew the screw a quarter of a turn if the engine did not stall, or half a turn if it stalled. Start the stalled engine. Check by opening the throttle as the engine picks up speed. Continue to unscrew the screw a quarter of a turn until the engine starts to accelerate steadily during gas blowing. This will be the moment of the most economical stable engine operation. For the PRORAB-8406 petrol trimmer, the adjusting screws are turned clockwise, unscrewed. counterclockwise, for some other brands the lawn mower can be the other way around.

Idle speed adjustment

We start adjusting low speed. The screw limits the return movement of the throttle lever. by turning it, we increase the idle speed, unscrewing it, we decrease it. Adjust so that the engine runs confidently at low revs and even slightly accelerated (for better starting), but so that the line reel or knife does not rotate, and there is a sufficient reserve of revolutions before they start spinning. If the engine starts poorly, increase the idle speed even more.

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Fuel ratio

I read somewhere that if different mixing ratios are indicated in the operator’s manual for the lawn mowers and on the oil canister, the proportion indicated in the manual should be used.

For a long time he did this. excess oil flowed from the engine onto the gas tank and carbon deposits were constantly formed on the candle, since the manual indicated the proportion for the run-in engine 1:25, and on the canister. 1:50. After switching to a ratio of 1:50, the appearance of oil drips stopped. The candle continued to burn, but at a lower intensity (the carburetor was not yet adjusted).

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Until now, some users of gasoline-powered tools determine the proportion of the fuel mixture “by eye”. If during the preparation of the mixture the amount of oil is underestimated, after a while an extraneous sound may appear immediately after starting the engine, gradually disappearing during warming up, and the engine stops with a sharp jerk. Continued use of the trimmer in this mode will lead to its failure.

From personal experience

lawn mower or trimmer

A trimmer is a broader concept than a lawn mower (lawn mower), as it can also be electric. A petrol trimmer and a lawn mower are one and the same.

Some authors claim that the trimmer is a weaker tool than a more powerful lawn mower, which can be used for mowing shrubs. Personally, I have a tool with a maximum power of 1.7 kW and capable, as stated in the instructions, to mow small shrubs up to 10 mm thick. The user’s manual is called “Petrol trimmer.”.

Adjusting the carburetor lawn mowers, trimmer

Increased fuel consumption and the rapid formation of carbon deposits on the spark plug when using a properly prepared fuel mixture indicate the need to adjust the carburetor. Here’s how to tune trims with carburetors with one fuel adjusting screw.

Carburetor adjustment

Flush the air filter before adjusting the carburetor. It is recommended to rinse it after every 10 hours of operation. After that, you can start adjusting. The photo shows the PRORAB-8406 petrol trimmer carburetor as an example. The numbers indicate the adjusting screws that we will use.

PRORAB-8406 petrol trimmer carburetor adjusting screws

  • Fuel mixture adjustment screw.
  • Idle adjustment screw.
  • Maximum speed limiting screw.

Start a lawn mower and wait for it to warm up.

Carburetor adjustment FORTE lawn mowers

The petrol lawn mower has been successfully used for a long time in a variety of industries: for lawn maintenance in private plots, in housing and communal institutions, landscaping organizations, agriculture and forestry. The main competitive advantages of the products. low maintenance costs, increased reliability and ease of use.

Engine. the most important component of any technique. And so that it always works in the optimal mode for itself, it is recommended to fine-tune the carburetor.

How to repair the carburetor of lawn mowers with your own hands and why do they recommend doing this? Primarily to make sure that the engine is working properly and that the maximum productivity of the tool is 100% ensured.

FORTE lawn mowers carburetor setting:

Start the engine of the device and let it warm up for 10 minutes (if you observe the rotation of the cutting element at idle speed, turn the idle screw in the opposite direction, turn until the spool stops turning).

Gently rotate the right and left needles to the middle position. Important! Never twist the stopper, as this could damage the engine.

There are 3 adjusting screws to adjust the carburetor:

  • Right H. low speed screw
  • Lower T. idle screw
  • Left L. high speed screw

Right screw H. First of all, the low speed screw is adjusted.

Find the highest idle speed, for this slowly turn the screw to the left or to the right. After finding the maximum rpm position, turn the screw counterclockwise на turn.

Note: FORTE lawn mowers are shipped from the factory with the right screw completely removed (0.5 turn). At this stage, he should look at “11 o’clock”.

Bottom screw T. Responsible for adjusting the engine idle speed. Turning the screw counterclockwise decreases the number of revolutions. Counterclockwise. Increases.

Correct adjustment is only considered if:

  • Cold engine at idle running stably without jerking
  • A hot engine gives out understated rpm at idle
  • Sufficient headroom remains before the cutting system starts to work
  • Stable engine operation in any position

Note: From the FORTE factory, the lower screw H (idle), from a fully tightened state, was unscrewed by 8 revolutions and “2 hours” (at this stage it should be). Recommended idle speed for FORTE engines. 2900 rpm.

Left screw L. Fine adjustment of the highest idle speed.

Important! The engine of FORTE petrol lawn mowers at maximum speed must not run for more than 10 seconds.

Open the throttle, start the engine and turn the screw in a clockwise direction with a slight movement until the engine speed decreases.

Then slowly turn the screw L in the opposite direction until the engine starts to shake.

Finally, turn the screw clockwise a short distance again until the mower engine starts to operate in the appropriate mode for itself.

The design of the gas trimmer carburetor and its purpose

lawn mowers are equipped with two-stroke internal combustion engines. A carburetor is used to supply the air-fuel mixture to the engine cylinder. In the design of gasoline units, this is a key element, without which the operation of the internal combustion engine is impossible. over, this carburetor differs from a car device not only in size, but also in the principle of operation. In particular, this difference lies in the presence of a membrane that plays the role of a gas pump. It is due to the presence of a membrane that the considered devices in the design of two-stroke internal combustion engines are called membrane.

Structurally, the entire mechanism is a small piece with channels, valves and diaphragms inside. The carburetor body is made of aluminum, and the internal structure is shown in the photo below.

Before adjusting the carburetor of the lawn mowers with your own hands, you need to deal with all the constituent elements of the device in question. The lawn mower and trimmer carburetor consists of the following parts:

  • Diffuser or Venturi nozzle. through this nozzle, air is sucked into the system
  • Air damper. opens and closes the filtered air supply
  • Fuel channel of maximum speed
  • Fuel channels (jets) of idle speed XX and medium speed
  • Throttle valve. the amount of opening is adjusted by pressing the gas
  • Impulse channel fitting. connects to the internal channel of the engine crankcase
  • Fuel inlet (union) (2). fuel is supplied from the gas tank
  • Membrane (4). is responsible for sucking fuel from the gas tank
  • Fuel suction valve (3)
  • The valve for supplying fuel to the carburetor channel (5)
  • Filter element (6) or fine fuel filter
  • Fuel channel (10)
  • The needle of the needle valve (14). is responsible for the supply of fuel to the chamber of the control diaphragm
  • Chamber. the fuel mixture, which is fed through the jets and the throttle valve to the cylinder
  • Control diaphragm (18). provides manual fuel suction with primer
  • Diaphragm Connected Lever (17)
  • Idle speed screw (15)
  • The screw for adjusting the amount of fuel supplied to the diffuser (13)

Having an idea of ​​how the carburetor works inside, you have to figure out how it works. A detailed description of how the carburetor works on a two-stroke internal combustion engine using the example of a chainsaw is described in this material.

How does a lawn mowers carburetor work or how it works

The carburetor adjustment of the Chinese lawn mowers is completely identical to the adjustment of the European, Russian and manufacturer’s lawn mowers. To cope with the task of adjusting the carburetor on lawn mowers and petrol trimmers, you need to understand the principle of their operation. How the carburetor works on a lawn mower is described step by step and accessible below.

  • The carburetor of lawn mowers begins with fuel supply through the channel, as shown in the diagram
  • Suction of fuel into the carburetor takes place using a pulse channel connected to the crankcase. Due to the rarefaction of air, the flexible membrane moves at number 4 in the diagram above.
  • Fuel is supplied through valves 3 and 5. Valve 3 is inlet, due to which fuel is supplied to the under-membrane space, and valve 5 is outlet
  • Further, the fuel moves along the channel and, passing through the fine filter, reaches the needle valve 14
  • The needle valve is connected by means of a lever to the control diaphragm 18
  • The needle valve is actuated by acting on the diaphragm. When it is necessary to pump fuel to start the engine, it is necessary to act on the soft cover of the hand pump. Upon exposure, the needle opens, and the chamber is filled with a fuel mixture.
  • When the engine starts (cold), the opening of the needle occurs due to the vacuum with the air damper closed. This vacuum acts through the idle and high speed nozzles on the diaphragm 18
  • The membrane acts through a lever on the needle valve, whereby the chamber is filled
  • After starting the engine, the air damper opens, as a result of which the engine runs on a lean mixture, as the fuel mixes with air
  • When the chamber is full, the fuel mixture is supplied (sucked in) through the nozzles of idle speed and medium speed (when the engine is running)
  • At the same time, the throttle valve is displaced from the initial position by 10-15 degrees
  • When the work is carried out under load, the fuel begins to flow into the chamber through the high speed jet, and at the same time the throttle valve rotates through 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, and thereby the mixture in the cylinder is ignited.
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Below is a diagram of the principle of operation of the lawn mower carburetor. Based on the diagram, you can not only figure out the principle of operation, but also identify breakdowns and other malfunctions of the mechanism.

When using the tool, it is necessary to take into account the presence of one more jet. This jet is located between the idle and full power channels. It is necessary in order to exclude a strong depletion of the mixture, which happens when the engine is running at partial load. In such a situation, the occurrence of a badass couple is not excluded. Through an additional channel (jet), fuel is sucked into the chamber, whereby the fuel-air mixture is enriched. The diagram below shows an additional jet, which is indicated by the number 1.

Having an idea of ​​the design of the membrane carburetor for lawn mowers and the principle of operation, it will not be difficult to customize it yourself. The lawn mowers use adjusting screws to adjust the carburetor. The diagram above shows two adjustment screws, however most modern petrol trim models have three screws. The presence of three adjusting screws allows for more accurate adjustment, while achieving stable and uninterrupted operation of the internal combustion engine.

How to know if a lawn mower carburetor needs adjustment

Many craftsmen use lawn mowers for a long time without thinking about the need to adjust the carburetor of the tool. When is it necessary to adjust the carburetor on a lawn mower or lawn mower? If you are asking such a question, then for sure there are changes in the operation of the motor not for the better. In order not to guess, and not to miss the moment of the need to adjust the carburetor, you should adhere to the following recommendations about the need for adjusting measures:

  • After the engine has run-in. Usually, the break-in lasts during the combustion of 4-5 liters of fuel.
  • When a fuel mixture of a different composition is poured into the tank, that is, the type of oil (even its color) and the brand of gasoline change
  • When weather conditions change, however, this is more relevant for chainsaws, gas generators and motor pumps, which are operated not only in summer, but also in winter.
  • If the mower has not been used for a long time. The reason for the need for adjustment may be a winter break
  • When fuel consumption increases
  • If black carbon is found on the spark plug electrodes
  • In the absence of gasoline entering the cylinder or poor engine start
  • If a large amount of exhaust gas is detected
  • Unstable operation of the engine, as well as its difficult start and “sluggish” set of revolutions

As you can see, there are enough reasons for adjusting the carburetor for lawn mowers. Usually, craftsmen who work with the tool for a long time detect changes in the operation of the motor by ear, which promises the need for an adjustment process. Even if you are not sure of the need for adjustment work, then their extraordinary performance will definitely not be superfluous.

The device and adjustment of the carburetor on lawn mowers and trimmers

a lawn mower or trimmer with an internal combustion engine requires not only constant refueling of the fuel mixture of gasoline and oil, but also periodic adjustment of the supply of this fuel. The carburetor is responsible for supplying fuel to the cylinder of the lawn mowers, the efficiency and performance of the tool depend on the correct operation of which. If, during operation, a faulty (abnormal) engine operation is detected, then the first step is to adjust the carburetor of the lawn mowers. Before setting up the carburetor of the gasoline trimmer, let’s first deal with its design.

Adjusting the carburetor on lawn and lawn mowers. setup instructions with step-by-step description

The very process of adjusting the carburetor of a lawn mower or trimmer is not difficult, however, its implementation should occur step by step in compliance with the recommendations. Before starting work, it is necessary to carry out preparatory actions, namely:

  • Flush the engine. desirable but not required
  • Check the spark plug, and if necessary clean it, measure the gap and replace it. Do not forget that candles have their own resource and are consumables. Sometimes the unstable operation of the internal combustion engine can be associated precisely with the malfunctioning of the spark plug
  • Check whether the carburetor is properly fixed to the cylinder-piston group, since the fastening very often weakens (or the gasket wears out), which leads to air leaks or primer. After tightening and replacing the gasket, the carburetor may not even need to be adjusted
  • Check the serviceability of the connecting adapter, which stands between the carburetor and the CPG
  • Clean the air filter or replace it. It all depends on the condition of the filter element. If the element is suitable for use, then the filter can be washed in soapy water, and then dried, and continue to use.
  • Attach the spool or cutting knives to the tool spindle. Adjustment is carried out under load, even if it is insignificant.

When all the preparation points are completed, we proceed to the direct process of setting up the carburetor. First, you should start the motor and let it run for 5-10 minutes, depending on the ambient temperature. When starting the motor at XX, the spool or knives on the trimmer should not rotate. If they are moving, then it is necessary to reduce the idle speed. The photo below shows an example of the location of the adjusting screws that perform the adjustment.

Using a slotted or Phillips screwdriver, we proceed to the direct process of adjustment work. First, we identify the number of screws for adjustment, since there can be 2 or 3 of them, depending on the manufacturer of the instrument. Usually Chinese trimmers are equipped with two screws. Below is the process of tuning the carburetor, which has three tuning screws:

  • Regulator marked L. you need to start tuning manipulations with it. It is necessary to rotate the screw while the motor is running. This screw is responsible for enriching the mixture at low rpm, so it should be screwed up so that the maximum value is reached. Typically, this bolt rotates until it stops and then looses of a turn. If dips are found, it is necessary to re-tighten the bolt until it stops, and loosen it by 1/8
  • Screw marked T or LA. this is used to adjust the idle speed. Turning the bolt to the right (tightening) increases the idle speed, and to the left, decreases it. When the speed of XX is increased, this means that more air is added to the combustible mixture. At the same time, the mixture is depleted, and power or thrust is lost. Reduced revolutions at XX indicate an excess of air in the mixture, so it is necessary to find a middle ground. The setting must be done so that the lawn mower engine runs stably at XX, and at the same time the line spool or steel cutting disc does not rotate. The rotation of the cutting elements contributes to the rapid wear of the clutch
  • Screw marked H. this screw is responsible for adjusting the combustible mixture at high speeds. It is with this screw that the tuning manipulations end. The maximum speed is indicated in the technical description for the tool. To determine the maximum speed value as accurately as possible, you should use a tachometer. If there is no tachometer, then the tuning is performed by ear. As soon as the maximum number of revolutions is reached by ear, the valve must be returned half a turn back (counterclockwise). Bolt H is responsible for power, temperature and fuel consumption

Often, it is with the setting of the maximum speed that difficulties arise. To prevent this from happening, the following actions are performed:

  • While pressing the gas, it is necessary to rotate the screw until the speed decreases (clockwise or to the right)
  • After reducing the speed, it is required to turn the bolt so (counterclockwise or to the left) to detect unstable engine operation
  • As soon as this unstable operation is detected, the screw should be turned clockwise until smooth operation of the internal combustion engine occurs.
  • This completes the adjustment process.

If the adjustment work is done correctly, the tool will work stably, the cutting element will not rotate at idle speed, and the fuel consumption will be the same as on the new trimmer. Tuning a carburetor with two screws is much easier, but the tuning accuracy is much lower. Usually 2 screws are equipped with Chinese gasoline-powered tools, as well as household units.

Summing up, it should be noted that you can not understand the principle of operation of the membrane carburetor lawn mowers and trimmers. It is important to have a screwdriver and a tachometer for adjustment. However, in order not only to adjust, but also to understand what you are doing, it is imperative to know the design and principle of operation.