Stihl Trimmer Carburetor Setting

How to adjust the carburetor on a chainsaw and properly adjust the idle speed with your own hands Adjusting the carburetor of a chainsaw is performed in several stages. It is necessary to assess possible problems in operation and the condition of structural elements, and then carry out adjustment measures.

How to adjust the carburetor on a chainsaw and properly adjust the idle speed with your own hands

For self-tuning the carburetor, you need to familiarize yourself with its device and remember the order of work that is carried out to adjust the parts that are responsible for the correct functioning of the constituent elements of the device and nearby parts. It is necessary to carefully handle objects for adjusting the chainsaw system, as well as to determine the correspondence of the set parameters to the maximum permissible values.

How to properly adjust a factory saw

Carburetor adjustment is divided into two main steps. The first is called basic. It is performed with the engine running. The second is performed when the engine is warm.

How to properly tune a Chinese saw. Adjusting instructions

In order to correctly configure the carburetor of a Chinese chainsaw, you must first remember the factory settings of the device, then turn on the engine. Subsequently, you will have to leave it to work for several hours in order to accurately set your own parameters. Sometimes the work is performed once after ten minutes of engine operation, but many Chinese-made models require special handling.

Adjustment procedure:

  1. Activities start in idle mode. With the help of the adjusting screws, you need to achieve a systematic set of revolutions by the engine, so you should first let it run at low speeds. The deviation from the norm is the movement of the chain along the tire. In this case, the end screws must be adjusted to the optimal position so that the chain remains stationary.
  2. Transition to average speed. Sometimes the engine will smoke. This defect can be eliminated by tightening the screw to supply a leaner fuel mixture.

Before buying, we recommend that you familiarize yourself with the rating of chainsaws for reliability and quality.
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Carburetor for trimmer: device, do it yourself setting

Stable and efficient operation of a household trimmer largely depends on the quality of the fuel used by the operator. The filled fuel mixture must be enriched with air. A built-in carburetor is responsible for this in the basic device of the lawn mower. This knot is one of the main elements of the streamer, so the operator must constantly monitor its serviceability and settings. Otherwise, the trimmer will lose its performance and may completely fail.

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Lawn mowers carburetor device

The standard design of any gasoline trimmer necessarily includes a fuel system, the basis of which is the action of a regular carburetor. Its design 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 zone of the smallest diameter the level of air vacuum becomes maximum.

Stihl trimmer carburetor setting

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 lawn mowers carburetor device 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 motor, 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 cylinder of the motor 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 near the needle and gradually fills the chamber equipped with the control diaphragm.

The standard carburetor trim valve is connected to the diaphragm with a lever. Below the built-in membrane 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 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 slow set of revolutions;
  • Lack of fuel flow into the cylinder of the power unit;
  • An increase in the volume of emitted waste gases.
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The lack of timely adjustment of the carburetor threatens with serious damage to the trimmer, up to the complete failure of its factory engine.

Adjusting the idle trimmer

Location of carburetor adjustment screws

The “T” (“AT”) screw serves as a limiter for the reciprocating movement of the fuel flap and when it is tightened, the engine speed increases, and loosening leads to a decrease in the crankshaft speed. Professionals advise adjusting the idle screw of lawn mowers so that the internal combustion engine runs a little faster at minimum speed, but the head with a fishing line or knife remains stationary. If after the performed manipulations it is difficult to start the trimmer “cold”, then it is enough to tighten the screw “T” a quarter of a turn and try to start the engine again.

Adjusting the fuel supply at minimum speed

Before you start tuning the carburetor of the petrol trimmer, you need to warm up the engine to operating temperature.

Fuel adjusting screws

To do this, we start the internal combustion engine and, at idle, let it run for 10-15 minutes. In the first step, with the trimmer working, slowly tighten the screw “L” until the start of intermittent operation or until it stalls. Next, unscrew the screw ¼ of a turn and check the maximum speed set. If the lawn mower reaches high revs quickly and easily, this will be the most economical mode. In most of the models on the market, the fuel screw “L” is turned clockwise, but there are trim tabs where the decrease and increase in the supply of the mixture occurs in the opposite order.

Carburetor Trimmer Adjustment

The initial step in restoring the correct operation of the fuel system is to clean the air filter.

Trimmer carburetor with screws

Experts recommend rinsing it in a solution of water and detergents after every 10-15 hours. Direct adjustment of the carburetor trimmer is done with three adjusting screws:

  • Fuel adjustment screw (“L”);
  • High speed adjustment screw (“H”);
  • The screw responsible for the engine idling (“T” or “AT”).

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 when compressed 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.

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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 that have one fuel trim screw.

Fuel ratio

I read somewhere that if different mixing ratios are indicated in the lawn mower’s manual 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 constantly formed on the spark plug, since the manual indicated the proportion for the run-in engine 1:25, and on the canister. 1:50. After switching to a 1:50 ratio, the appearance of oil drips stopped. The plug continued to burn, but with less intensity (the carburetor was not yet adjusted).

Until now, some users of gas-powered tools determine the proportion of the fuel mixture “by eye”. If the amount of oil is lowered during the preparation of the mixture, 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 result in its failure.

Do-it-yourself lawn mowers carburetor adjustment

Lawn mowers, like all gas powered garden tools, are not difficult to maintain. It is possible and necessary to repair, configure yourself. For example, adjusting the carburetor of a lawn mower with your own hands is a matter of five minutes.

A lawn mower carburetor is a unit in the power system. In it, like any carburetor, there is a process of mixing air and fuel (gasoline) for further supply to the engine cylinders.

Lawn mowers carburetor device

The basis of the carburetor for lawn mowers is an aluminum body. It contains a diffuser (hole with internal 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 an air stream.

Outside the carburetor is installed:

  • Fuel pump;
  • Jet system;
  • Fuel-air mixture control system;

The main problems and malfunctions of the carburetor.

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

  1. Blockage.
  2. 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 compressed air into clogged carburetor parts is an acceptable and convenient repair practice.