Adjusting the carburetor Stihl 55 lawn mowers

Removal and installation algorithm

In cases where it is necessary to clean the Stihl 180 carburetor or disassemble it, you first need to remove the assembly from the chainsaw. This must be done in compliance with a certain algorithm of actions:

  • Put the protective cover for the chainsaw on the tire.
  • Remove the top cover of the chainsaw.
  • Remove the two nuts securing the air filter and carburetor.
  • Remove the air filter housing.
  • Disconnect the wire from the engine control lever.
  • Carefully remove the lever from its seat in the housing, at the same time disconnecting the air damper rod from it.
  • Pull the carburetor towards you and disconnect the fuel supply as well as the throttle rod.

To facilitate dismantling, you can additionally untwist the rear handle and disconnect the throttle rod first from it, and then only from the carburetor. This may be required, because without some experience, disconnecting the rod from the carburetor is quite problematic and it is easier to disassemble the handle first.

To install the part in place, follow the reverse order of the algorithm.

When removing and installing the chainsaw engine control lever, you should be extremely careful, since the seat on the saw body is the weak link of the saw, and very often inexperienced users break it.

Why does the Stihl 180 carburetor overflow and a few typical malfunctions

After we have examined the carburetor device, it will not be difficult to determine the reason why fuel enters the combustion chamber in a larger volume. This is due to the wear of the gasket between the compensator cover and the carburetor body. You ask how this might affect?

The answer is simple, by shrinking, the gasket releases the diaphragm on top of it a fraction of a millimeter down. She, in turn, will press harder on the rocker arm of the needle valve, it will open more than it should be and the fuel will flow in excess (it will start to overflow).

Another reason is the stretching of the diaphragm itself, this occurs as a result of natural wear and tear. It is impossible to prevent this process, but you can solve the problem by periodically changing all the gaskets, carburetor diaphragms, and the fuel pump. There is a repair kit for this.

adjusting, carburetor, stihl, lawn, mowers

When cleaning the chainsaw with compressed air, never blow into the fuel pipe, as this can stretch the diaphragm.

Air damper

The carburetor choke is installed on the opposite side of the throttle and is responsible for starting a cold engine, it is controlled by the engine control lever. For a cold start, the air damper is completely closed, for normal operation, open.

Frequent Stihl carburetor breakdown and how to avoid it

A common reason for the failure of a carburetor on a Stihl chainsaw is a sticking valve in the nozzle. The reason for sticking is a violation of the storage of the chainsaw, or rather the instructions of the manufacturer Stihl 180 for proper preparation for storage.

As follows from the instructions, before long-term storage, it is necessary to drain the fuel from the tank, then start the saw and burn the gasoline from the carburetor. Failure to comply with this elementary rule entails the following consequences. The forsknui valve, being in direct contact with the fuel, sticks to the body, since the gasoline evaporates little by little and only sticky oil remains. It is impossible to replace the nozzle, since they are not in the repair kit, you can only try to knock it out and rinse it, which is not always possible to do without damaging the nozzle.

Dismantling the carburetor Stihl 180

In order to purge, change gaskets or the needle valve, the carburetor must be disassembled. To do this, unscrew 4 screws on the expansion joint cover and one on the fuel pump.

Having opened the case, you should be extremely careful, because if debris gets into the inside of the carburetor, it will make its work impossible. The thickness of the channels in it is comparable to the thickness of a thread or even a human hair.

A video for repairing a Stihl 180 carburetor can be viewed below. In it, the master tells in detail about the problems and clearly demonstrates the entire repair process.

Distribution chamber

In the distribution chamber, as in the fuel pump, there is also a membrane that opens and regulates the fuel supply by pressing a special rocker, while raising its needle valve.

The chamber cover is the compensator body, which is attached to the carburetor with four screws, a gasket is installed between the body and the cover, which increases the height of the chamber and is responsible for sealing.

Fuel pump

A fuel pump is installed directly in the carburetor body, which operates under the action of an air pulse from the crankcase of the chainsaw, which is transmitted through special channels. A diaphragm is installed in the pump, it is she who is responsible for pumping fuel under the action of an impulse. A gasket is installed between the diaphragm and the body, which is responsible for the tightness of the fuel pump.

Throttle flap

The throttle valve is installed in the carburetor body and is responsible for increasing the supply of the fuel mixture directly to the engine cylinder. At the moment of pressing the gas, the throttle valve opens slightly, thereby increasing the throughput of the channel and fuel from the carburetor cavity, rushes into the cylinder in a larger volume.

Combustion of a larger volume of fuel increases the amount of generated energy, which affects the power and speed of the processes. The damper is mounted on a shaft running through the entire carburetor body. At the exit of the shaft from the housing, a mount for the gas cable is installed, next to it is a cone-shaped adjusting screw responsible for adjusting the idle speed. By tightening the screw, you can slightly adjust the position of the shaft and the damper installed on it, thereby increasing or decreasing the idle speed, slightly opening or vice versa closing the damper.

Adjustment and repair of the carburetor lawn mowers

The trimmer does not belong to complex household appliances, therefore, most of its breakdowns are mechanical in nature and are quite successfully eliminated with their own hands. Even if the engine fails for serious reasons. damage to the piston ring, for example, repairs are reduced to replacing a part.

But even with a relatively simple design, such a part of the device as a carburetor needs to be adjusted.

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Principle of operation

A carburetor is a power system module in which liquid fuel and air are mixed before being fed into the engine cylinders. Mixing and flow are adjusted accordingly depending on the tool and its mode of operation.

Stihl fs 55r carburetor adjustment tune up

The carburetor device for lawn mowers is the same for almost all cases. It belongs to the category of float devices. The latter provide stable parameters of ready-made mixtures.

The principle of the module is as follows.

  • Air enters the body of the air damper tube. The latter increases or decreases the air flow depending on its position.
  • In the area where the hole for the gasoline supply is formed, the tube has a narrowing. a diffuser. Here the flow rate increases.
  • Fuel from the float chamber is fed through the 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 the pipeline.

The more open the air damper in the tube, the higher the density of the air flow, and, therefore, more fuel enters the cylinder. Adjusting the carburetor of lawn mowers is reduced to setting such a ratio of flaps, at which the density of the fuel mixture becomes optimal.

Signs of imbalance

Debugging the carburetor is mandatory during the manufacture of the device. As a rule, the owners will find out about the need to adjust the fuel supply with their own hands only after serious enough breakdowns, in the process of correcting which, the module was removed and, for example, cleaned.

  • starts, but the engine immediately stalls. since the engine can only work when a certain amount of gasoline is supplied, with too “lean” fuel, that is, blocking the supply channel, the engine will stop;
  • too high 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 is too dense.

The carburetor for lawn mowers Stihl, Makita, Husqvarna and others is adjusted using the adjusting screws. Sometimes the reason for the 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 turn the screw slightly: if the fixation is not rigid, it is worth checking the setting.

DIY lawn mowers carburetor adjustment

Setting up the module does not apply to repair and replacement of spare parts is not required. In this case, the lawn mowers carburetor repair kit will not be needed.

Three screws are provided for debugging:

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

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

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

If there is a tanometer, and if the recommended rpm values ​​are indicated in the product passport, the correction can be made more accurate, focusing not on hearing, but on the readings of the device.

The adjustment of the carburetor of the lawn mowers in the video was carried out by ear.

8 comments on the entry “Adjustment and repair of the carburetor lawn mowers

Correct Way To Adjust Or Tune The Carburetor On A Weedeater / Grass Trimmer. Video

    Dmitry Pavlovich 07/04/2016

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

prompt the initial position of the screws H L LA


prompt the initial position of the screws H L LA

Thank you very much for the video about the accelerator and did not know, but the defect is very important and creates a huge problem that almost everyone is silent about. BRAVO….

Maybe all the same tachometer is a rpm meter, and not a tonometer blood pressure meter

and I have L, H, LA, it’s LA instead of T?

The video shows some kind of tightness, so you need to be able to chew snot.

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.

It is interesting! What is the difference between a trimmer and a lawn mower? Many people think that the trimmer is a low-power electric lawn mower. However, the trimmer is a generic name for lawn mowers, lawn mowers and electric mowers as they are intended for general purposes.

Lawn mowers device

The device of the Stihl FS 55 lawn mowers should be clear to you if you plan to operate the equipment, let alone repair it. The internal combustion engine in this unit is almost the same as in a chainsaw. But the tire is the latter fixed to the motor reducer by a long tubular rod. Inside there is a shaft that transmits torque from the motor to the working tool. This design is suspended from a strap that is slung over the shoulder. This allows you to hold the tool on the weight, which is fundamentally with the sensitive weight of the chainsaw.

A handle is fixed to the bar of the unit, with the help of it you can move the end of the bar with the working equipment. the Stihl FS 55 lawn mower, the repair summary of which is presented in the article, has a protective shield in the form of a casing on the human side, which excludes injuries during operation. The tool itself is a round drum with thick line coming out of the holes on both sides. Adjusting the carburetor and chainsaw repair lawn mowers Stihl stihl fs55 fs 38 carburetor. When the drum spins, the line pulls under the action of centrifugal force and hits the grass, chopping it.

Lawnmower “Stihl FS 55”, the technical properties of which will be presented to your attention below, has a wear-resistant nylon line. Features of the Stihl fs 38 lawn mowers, carburetor adjustment of the Stihl fs 38 lawn mowers. It is renewed from time to time by unwinding the reel, which is inside the drum.

Elimination methods

The list of upcoming work on the engine may be as follows:

  • replacement of the fuel pump;
  • disassembly and flushing of the strainer;
  • replacement of the adjusting lever;
  • it is also necessary to clean the adjustment space;
  • replacement of the membrane (or the entire block where this membrane is located);
  • adjusting the inlet, outlet and needle valves;
  • replacement of dampers;
  • cleaning fuel channels and diffuser;
  • replacement of screw springs;
  • change of primer.

Not all of this work can be done. Often it turns out that many of them are not needed if a specific malfunction is immediately detected.

Starting the motor

The engine is started at a distance of 3 m or more from the place where the device is filled with fuel. These works cannot be performed indoors. Until you need to take a stable, secure position. With all this, the motorcycle is held very tightly. The cutting tool should not come into contact with the ground or objects, because when starting it can spin.

The unit is serviced by only one person, with all this, there should be no outsiders in an area with a radius of up to 15 m. Otherwise, you may get injured from thrown objects. The motor start of the Stihl FS 55 lawn mowers, the properties of which are presented in the article, should not be carried out by hand. After releasing the throttle, the cutting tool will coast for a while. Flammable materials should be kept away from the hot gas stream and the surface of the hot muffler, as this could cause a fire.

Gas trimmer carburetor repair tips

Regardless of the manufacturer, there is a factory defect in the carburetor parts of the lawn mowers.

For example, the tuning technique described above may not give positive results if the number of turns at the spring of the screw for supplying the mixture is too large and, as a consequence, the impossibility of optimally reducing the level of supplied gasoline. To eliminate this, you can independently shorten the spring a little or, in accordance with the operating manual, purchase a new one.

Many lawnmower owners follow the fuel mixture recommendations listed there when buying oil.

So, often the information on mixing gasoline with oil indicated on the bank differs from the instructions in the trimmer passport. As a result, black carbon deposits can quickly form on the spark plug, leading to a drop in power and increased fuel consumption. Therefore, when preparing the working mixture, you should follow the recommendations specified in the operating manual. In most cases, the proportion for a run-in ICE is 1:25. It should be noted that many tool owners prefer to prepare fuel “by eye”, which will certainly lead to rapid wear of the piston streamer in the event of a decrease in the portion of oil and the formation of carbon deposits on the spark plug with an increased amount of lubricant.

Tips for adjusting the trimmer carburetor correctly performed above will help to avoid not only engine overheating, increased fuel consumption, but also significantly increase the service life of other parts and assemblies of the tool

READ  What Gasoline To Fill In A Husqvarna Lawn Mower

Pay attention to the operation of the lawn mowers in all modes and carry out the regulated maintenance and repair of the tool in time.

Broken primer

Primer is a mini hand pump for forced pumping of fuel into the carburetor. For a successful start of the engine, it may be necessary to pump 20 ml of gasoline manually.

How to adjust the carburetor on a lawn mower

The upcoming do-it-yourself lawn mowers carburetor setting is done with adjusting screws. There are three of them:

Right (L). Fuel Consistency Adjustment for Low RPM.

It is necessary to find the highest idle speed. To do this, slowly unscrew the screw (L) to the right and to the left.

To adjust, turn the screw a quarter of a turn certainly counterclockwise.

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

  • clockwise. increase;
  • counterclockwise. decrease.

For the correct adjustment of the idle speed specifically, it is characteristic:

  • stable operation of a cold engine;
  • not overestimated speed of a hot engine;
  • a large reserve of turns for the trimmer head;
  • stable operation of the engine when changing position (sharp lifting or lowering of the knife).

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

The left screw (H) determines the general adjustment of maximum speed, engine power, temperature and gasoline consumption.

The carburetor setting for lawn mowers with the last screw is done as follows:

  • Open the throttle to full, at the same time give full throttle. Turn the screw clockwise until the speed drops (in this case, orientate by ear).
  • Turn the screw counterclockwise as slowly as possible until the engine runs unevenly.
  • Then turn back quite a bit, barely hearing a stable, even operation.
  • For a more visual use of skills, it is more convenient to consider the work of an experienced user:

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 only by the speed and stability of the engine.

do it yourself

The principle of operation of the carburetor lawn mowers

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

Fuel is sucked into the carburetor system by a pump (its membrane). Then it passes through the choke in the carburetor. The fluid then flows through the pump inlet and outlet valves. Filtered by the grid. Moves through the needle valve into the diaphragm chamber.

Step-by-step operation of the device:

  • Air supply to a tube with an air baffle (damper). The baffle regulates the intensity of the air flow.
  • The fuel supply system is necessarily narrowed by a diffuser to increase the flow rate.
  • Gasoline through the float chamber and the nozzle tube with a constriction. A float chamber adjusts the temporary volume of gasoline. In the float chamber, the pressure level is neutral, and in the tube with a constriction it is already low. Due to the differential pressure, the fuel penetrates through the nozzle.
  • The acceleration of the air flow facilitates 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 about creating an optimal fuel mixture through the correct air supply.

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).

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.

Do-it-yourself lawn mowers carburetor adjustment

A lawn mower carburetor is a unit in the power system. In it, like any carburetors, there is a process of mixing air and fuel (gasoline) 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 is regulated.

Lawn mowers carburetor device

The basis of the carburetor for lawn mowers is an aluminum body. It contains a diffuser (hole with inner contours). Air is blown through this hole. The flow rate of oxygen (air) depends on the cross-section (orifice) of the diffuser.

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

Outside the carburetor is installed:

  • fuel pump;
  • jet system;
  • a system for adjusting the mixture of fuel and air;

How to adjust the carburetor on a lawn mower

Before adjusting, you must thoroughly clean the filters according to the maintenance instructions in the instructions.

Further adjustment of the carburetor of the lawn mowers with their own hands is carried out with the adjusting screws. There are three of them:

  • right;
  • left;
  • lower.

Right (L). adjusting the fuel mixture for low rpm.

You need to find the maximum idle speed. To do this, slowly unscrew the screw (L) to the right and left.

To adjust, turn the screw a quarter turn counterclockwise.

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

  • clockwise. increase;
  • counterclockwise. decrease.

For the correct adjustment of the idle speed, it is characteristic:

  • stable operation of a cold engine;
  • not overestimated speed of a hot engine;
  • a large reserve of turns for the trimmer head;
  • stable operation of the engine when changing position (sharp lifting or lowering of the knife).

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

The left screw (H) determines the general adjustment of maximum speed, engine power, temperature and gasoline consumption.

The carburetor setting for lawn mowers with the last screw is done as follows:

  • Open the throttle to full, at the same time give full throttle. Turn the screw clockwise until the speed drops (in this case, orientate by ear).
  • Turn the screw counterclockwise as slowly as possible until the engine runs unevenly.
  • Then turn back quite a bit, barely hearing a stable, even operation.
  • For a more visual use of skills, it is more convenient to consider the work of an experienced user:

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 only by the speed and stability of the engine.

Correct adjustment of the carburetor with your own hands in this case. combustion of the fuel mixture without residue, the color of the candle should be light brown.