Setting And Adjusting The Trimmer Carburetor
The stable and effective operation of the household trimmer is largely dependent on the quality of the fuel used by its operator. The filled fuel mixture must be enriched with air. For this, the built-in carburetor is responsible for this in the basic lawn mowing device. This node is one of the main elements of the braid, so the operator must constantly monitor its serviceability and settings. Otherwise, the trimmer will lose its performance and may completely fail.
The device of the carburetor lawn mowers
The standard design of any gas trimmer must include a fuel system, the basis of which is the action of a standard 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 assembly from moisture, small debris and dust. A built-in diffuser is provided in the lower part of the body, 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 assembly to enrich the fuel. The diffuser operates according to a simple principle: the smaller its diameter becomes, the more intensively the air is absorbed. This is due to the fact that in the zone of the smallest diameter the level of air discharge 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. Other carburetor parts: regular adjusting screws and a fuel pump, can be located both inside and outside the carburetor.
The carburetor of the lawn mowers includes a throttle, the main task of which is to regulate the amount of intake air. The greater the amount of air, the higher the rated power of the trimmer power unit. Another function of the damper is to facilitate the cold start of the engine. If the lawn mowing is started for the first time after a long period of inactivity, the shutter must be closed. Immediately after starting the motor, the part must be opened, otherwise the engine will die out.
The carburetor for the trimmer is equipped with a pulse channel that connects the internal cavity of the ICE crankcase with the pulse chamber of the pump. The piston located in the cylinder of the motor creates a reciprocating motion, which leads to gradual changes in pressure inside the crankcase. At the same time, the membrane is driven. Thus, the action of the pump is fully synchronized with the operation of the power unit.
The membrane of a regular carburetor takes an active part in fuel suction. It enters the fuel assembly through the fitting. After that, the fuel passes through the built-in intake and exhaust valves, then through the strainer and the fuel pipe. Then the fuel flows next to the needle and gradually fills the chamber equipped with a control membrane.
The regular valve of the trimmer carburetor is connected to the membrane using a lever. Below the built-in membrane is a cavity into which air is drawn in through a special opening.
The carburetor for lawn mowers works on this principle in stages. This ensures uninterrupted operation of the fuel unit and uninterrupted supply of fuel to the cylinder of a standard power unit.
When is the carburetor adjustment of a household trimmer required?
Adjust the built-in trimmer carburetor when:
- Running-in of a new engine, during which from 4 to 5 liters of fuel mixture were used;
- Sudden changes in weather;
- Changes in rarefaction of air. For example, when the lawn mowing is often used in mountainous areas;
- Long simple trimmer;
- Intensive growth of loads on the power unit of lawn mowers;
- Arbitrary unscrewing of the carburetor’s built-in adjusting screws. This becomes the cause of increased vibration of the internal combustion engine;
- Changing the quality of the components of the fuel mixture;
- Fuel transfusion with a carburetor, resulting in an increase in fuel consumption;
- Regular appearance of a thick layer of tarry deposits and soot on the surface of the electrodes of a regular trimmer spark plug;
- Engine start and its arbitrary shutdown or a slow set of revolutions;
- The lack of fuel in the cylinder of the power unit;
- Increase in exhaust emissions.
The lack of timely adjustment of the carburetor threatens serious damage to the trimmer, up to the complete failure of its factory engine.
DIY carburetor adjustment
Periodic adjustment of the trimmer carburetor should be performed on a serviced and fully functional power unit. Before starting the procedure, the operator must thoroughly rinse the engine parts and inspect its CPG for any burrs or other defects. In addition, you will need to clean or replace the spark plug, as well as rinse the filter elements in the construction of the lawn mowers.
Video: Setting And Adjusting The Trimmer Carburetor
During carburetor adjustment, the lawn mowing engine must run under a certain load. It is best to install a cord of the appropriate diameter or cutting knives on the trimmer.
After mounting the cutting organs, the operator should start the internal combustion engine trimmer and leave it to work for about 10 minutes. If during operation of the power unit at idle it was noticed that the cord or knife rotate, then you need to reduce the speed created by the motor. To do this, turn the lower control, often denoted by the letter “T”, to the left, until the installed cutting unit stops completely.
A 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 while the engine is operating at low revs. The position of this screw must be set first. To do this, the operator will need to achieve maximum engine speed when idling. For this you need to turn the screw “L” in turn to the right or left side. Once the maximum speed is reached, the screw will need to be rotated 1/2 turn to the left;
- Screw “T” or “LA” is required to adjust the idle speed. During its rotation to the left, the revolutions of the power unit will decrease, and when turning to the right. Accordingly, increase;
- The “H” regulator, provided on the left, is responsible for enriching the fuel mixture with air during the operation of the engine trimmer at high speeds. This screw is also needed to adjust motor power and fuel consumption. Its position is adjusted by turning the screw to the right or left side until the maximum permissible engine speed is reached. After that, screw “H” will need to be turned 1/2 turn to the left.
The sequential implementation of these actions will allow you to correctly configure the trimmer fuel assembly, without the risk of exceeding the permissible load on its main operating mechanisms.
Despite the high productivity, mobility and unpretentiousness in work, modern lawn mowers are difficult to attribute to complex devices. Over time, any mechanism undergoes wear, and therefore parts and assemblies require special attention of the owner. One of the elements of the trimmer is a carburetor, designed to form a fuel mixture and its supply to the combustion chamber. Increased consumption with the correct proportions of gasoline and oil or a drop in engine power indicate the need to adjust the carburetor of the gas trimmer.
Trimmer carb setting
The initial step in restoring the correct operation of the fuel system is to clean the air filter.
Screw trimmer carburetor
Experts recommend rinsing it in a solution of water with detergents after every 10-15 hours. Direct adjustment of the trimmer carburetor is carried out by three adjusting screws:
- Fuel feed adjustment screw (“L”);
- Adjustment screw at high speeds (“H”);
- The screw responsible for idling the motor (“T” or “AT”).
Adjustment of fuel supply at the minimum turns
Before starting the carburetor adjustment of the gas trimmer, it is necessary to warm the engine to operating temperature.
Fuel Adjustment Screws
To do this, start the engine and at idle let him work 10-15 minutes. At the first stage, with the trimmer working, slowly tighten the screw “L” until the beginning of intermittent operation or until it dies. Next, unscrew the screw by ¼ turn and check the speed of maximum speed. If the lawn mower easily and quickly reaches high speeds, this will be the most economical mode. In most models on the market, the fuel screw “L” is turned clockwise, however, there are trim tabs where the decrease and increase in the mixture flow occurs in the reverse order.
Trimmer idle adjustment
Location of carburetor adjustment screws
The screw “T” (“AT”) serves as a limiter of the reciprocating movement of the fuel shutter and when it is twisted, the engine rpm increases, and turning it off leads to a decrease in the crankshaft speed. Professionals advise adjusting the idling screw of the lawn mowers so that the ICE works a little faster at minimum speed, but the head with the fishing line or knife remains motionless. If it is difficult to start the trimmer “cold” after the manipulations, then it is enough to tighten the “T” screw a quarter of a turn and try to start the engine again.
Adjustment of the screw of the maximum turns of a lawn-mowing
After restoring the fuel supply at minimum speed and adjusting the idle speed, it is necessary to check the stability of the mechanism at an increased speed.
Setting at maximum speed
Adjustment of the motor at high speeds is carried out in order to protect against overheating and reduce hand fatigue when pressing the accelerator key. If the internal combustion engine is unstable at maximum speed, then screw “H” must be slowly turned in to ensure smooth and clear operation.
During operation of the lawn mowers, it may be necessary to adjust the fuel feed screw (“L”) for an optimal set of revolutions.
Tips for repairing a gas trimmer carburetor
- Regardless of the manufacturer, there is a factory defect of the carburetor parts of the lawn mowers.
Adjusting screw spring
For example, the adjustment procedure described above may not give positive results with an excessively large number of turns at the spring of the mixture feed screw and, as a result, the impossibility of optimally reducing the level of gasoline supplied. To eliminate this, you can independently shorten the spring yourself or purchase a new one in accordance with the instruction manual.
Many owners of lawn mowers when buying oil follow the recommendations indicated there for the preparation of the fuel mixture.
Oil for gas trimmer
So, often the information on mixing gasoline and oil indicated on the bank differs from the instructions in the trimmer’s passport. As a result, a black deposit can quickly form on the spark plug, which leads to a drop in power and an increase in fuel consumption. Therefore, when preparing the working mixture, the recommendations specified in the instruction manual should be followed. In most cases, the proportion for a run-in ICE is 1:25. It is worth noting that many tool owners prefer to cook fuel “by eye”, which will inevitably lead to rapid wear of the piston spit in the event of a decrease in the portion of oil and the formation of soot on the spark plug with an increased amount of lubricating fluid.