Trim Setting

Carburetor for trimmer: device, do-it-yourself tuning When do you need to adjust the carburetor of a household trimmer? Carburetor device lawn mowers, do it yourself carburetor adjustment

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;
  • Changing the 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 carburetor adjusting screws, 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.
trim setting

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

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 for this in the basic device of the lawn mower, the built-in carburetor is responsible. 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.

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 the 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.

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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 volumes 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 flows 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.

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 running, slowly tighten screw L until intermittent operation starts 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, however, there are trimmers where the decrease and increase in the mixture flow occurs in the opposite order.

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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 rpm increases, and loosening leads to a decrease in the engine 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 these manipulations it is difficult to start the trimmer to cold, then it is enough to tighten the screw T a quarter of a turn and try to start the engine again.

Carburetor Adjustment Lawn Mowers Highlights

Despite their high productivity, mobility and unpretentiousness in work, modern lawn mowers can hardly be attributed to complex devices. Over time, any mechanism is subject to wear and tear, and therefore parts and assemblies require special attention from the owner. One of these trimmer elements is the carburetor, designed to form a fuel mixture and feed it into the combustion chamber. Increased fuel consumption with proper observance of the proportions of gasoline and oil or a drop in engine power indicate the need to adjust the carburetor of the gasoline trimmer.

Fuel supply adjustment

Begin to slowly tighten 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 has not stalled, 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 screw # 1 by 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 of lawn mowers it may be the other way around.

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.

Lawn mowers carburetor device

The base of the carburetor 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.

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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 carburetor parts is an acceptable and convenient repair practice.

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.

Trimmers and chainsaws

Trimmer tuning (trimmer modernization) is a technical improvement of the trimmer, lawn mowers, lawn mowers or electric mowers by replacing parts and assemblies with more expensive or improved ones, adding unusual parts and assemblies to the trimmer design, as well as better and more accurate tuning and adjustment of all assemblies and systems to improve technical characteristics and appearance of the trimmer.

Additional trimmer tuning

  • Install a four-stroke engine with an automobile-type muffler on the trimmer (so that it “whispers” quietly).
  • Make a two-cylinder two-stroke engine (see the article about a two-cylinder chainsaw) to reduce vibration and increase trimmer power (like IZH Jupiter, only smaller, for example, 2 cylinders of 25-35 cm3 each).
  • Enclose the two-stroke engine of the scythe in a sealed soundproof capsule (like engines of Mercedes trucks).
  • From the muffler of the two-stroke trimmer engine, pull back (parallel to the boom) a double (one into the other) metal pipe with noise insulation, for example, 60 cm long mineral wool, to divert the roar and smoke from the engine further back.
  • Attach a wide-grip rechargeable flashlight to the trimmer bar for working in the dark, after making a convenient mount for it.

Support cup for protecting and sliding the trimmer head on the grass

Replace the button at the bottom of the trimmer head with a wide support cup as shown in. This will allow you to keep an even cut of the lawn, that is, the same lawn mowing height.

A trimmer from a lawn mower is primarily distinguished by the fact that the lawn mower cuts the lawn evenly, and it is difficult to keep the same cutting height on the trimmer, since the trimmer head swings up / down.

Also, with such a cup under the trimmer head, you do not need to keep the trimmer head suspended (the trimmer head slides on the grass, copying the surface of the plot) and you should not be afraid to damage the trimmer head by hitting it against a solid, stationary object (for example, a stone in the grass, a concrete fence post or about some iron object).