Gasoline mowers or trimmers with internal combustion engines require not only constant refuelling 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 gasoline mowers, and the performance and performance of the tool depend on the proper operation of the carburetor. If in the process of work a faulty (abnormal) engine operation is detected, then the carburetor of the gas mowers is adjusted first. Before you adjust the carburetor gasoline trimmer, let’s deal first with its design.
The design of the petrol trim carburetor and its purpose.
Trimmer equipped with two-stroke type internal combustion engines. For the supply of air-fuel mixture in the engine cylinder, a carburetor is used. In the design of gasoline units. is a key element, without which the work of the engine is impossible.
over, this carburetor differs from a car device not only in size but also in its working principle. In particular, this difference lies in the presence of a membrane, which plays the role of a fuel pump. It is due to the presence of the membrane, the considered devices in the design of two-stroke internal combustion engines are called membrane.
Structurally, the whole mechanism is a small part, inside which there are channels, valves and membranes. The carburetor body is made of aluminum, and the internal device is shown in the photo below.
Before the adjustment of the carburetor of the gas mowers will be made with your own hands, it is necessary to deal with all the constituent elements of the device in question.
The carburetor Trimmer and trimmer consists of the following parts:
- Venturi diffuser or nozzle. through this nozzle air is sucked into the system
- Air damper. opens and closes filtered air supply
- Maximum speed fuel channel
- Fuel channels (jets) idling twentieth and medium speed
- Throttle. opening is regulated by pressing the gas
- Pulse channel fitting. connects to the engine crankcase internal channel
- Inlet fuel channel (socket) (2). fuel supply from the fuel tank is provided
- Membrane (4). is responsible for the absorption of fuel from the gas tank
- Tank suction valve (3)
- Valve fuel supply to the carburetor channel (5)
- Filter element (6) or fuel fine filter
- Fuel Channel (10)
- Needle of the needle valve (14). is responsible for the flow of fuel into the chamber of the control membrane
- Chamber. fuel mixture, which is fed through the nozzles and the throttle valve in the cylinder
- Control membrane (18). manual priming of fuel provided by primer
- Lever connected to the membrane (17)
- Screw adjust the idle (15)
- Screw adjusting the amount of fuel fed into the diffuser (13)
Having an idea of how the carburetor is arranged inside, it is necessary to understand the principle of its operation. A detailed description of how the carburetor on a two-stroke internal combustion engine works on the example of a chainsaw is described in this material.
How does the trimmer carburetor work or principle of operation.
The adjustment of the carburetor of the Chinese Trimmer is completely identical with the setting of lawn mowers European, Russian and manufacturers. To cope with the task of adjusting the carburetor on benzokosah and benzotrimmerah, you need to understand the principle of their operation.
How works the carburetor on the trimmer, step by step and affordable described below.
- The operation of the carburetor trimmer begins with the supply of fuel through the channel, as shown in the diagram
- Fuel is sucked into the carburetor using a pulse channel connected to the engine crankcase. Due to the rarefaction of the air, the flexible membrane numbered four moves in the diagram above.
- Through valves 3 and five there is a supply of fuel. Valve 3 is the inlet, due to which fuel is supplied to the submembrane space, and valve 5 is the exhaust
- Next, the fuel moves through the channel and, passing the fine filter, reaches the needle valve 14
- The needle valve is connected via a lever to the control diaphragm 18
- The needle valve is activated when acting on the membrane. When it is necessary to pump up fuel to start the engine, it is necessary to influence a softcover of the manual pump. When exposed, the needle opens, and the chamber is filled with the fuel mixture.
- When the engine is started (on the cold one), the opening of the needle occurs due to the vacuum with the air damper closed. This vacuum acts through the nozzles and high-speed nozzles on the membrane 18
- The membrane acts through the lever on the needle valve, whereby the chamber is filled.
- After starting the engine, the air damper opens, causing the engine to run on a lean mixture, as the fuel mixes with the air.
- The fuel mixture when the chamber is full is supplied (sucked) through the idling nozzles 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 turns at an angle of up to 90 degrees (depending on the pressure force on the gas). In all modes of operation, the air damper should be open, through which the fuel is mixed with air, and thus the mixture in the cylinder ignites
Below is a diagram of the principle of the carburetor Trimmer. Based on the scheme, it is possible not only to deal with the principle of operation but also to identify failures and other malfunctions of the mechanism.
When operating the tool, you must consider the presence of another jet. This jet is located between the channels of idling and full power. It is necessary to exclude a stable impoverishment of the mixture, which happens in the case of motor operation at partial load. In such a situation does not eliminate the occurrence of a badass pair. Through the additional channel (jet), the fuel is sucked into the chamber, whereby the fuel-air mixture is enriched. The diagram below shows the additional jet, which is indicated by the number 1.
Having an idea of the design of the membrane carburetor trimmer and the principle of operation, it is not difficult to tune it yourself. To adjust the carburetor Trimmer adjusting screws are used. The diagram above shows two screws for adjustment. However, the majority of modern models of petrol trimmers are equipped with three screws. The presence of three adjustment screws allows you to perform the more precise adjustment while achieving stable and smooth operation of the engine
How will I find that carburetor Trimmer needs adjustment?
Many masters use the trimmer for a long time, and at the same time, do not think about the need to adjust the carburetor tool. When is it necessary to adjust the carburetor on the trimmer? If you ask such a question, then surely there are changes in the work of the motor is not for the better.
In order not to guess, and not to miss the moment of the need to tune the carburetor, you should adhere to the following recommendations about the need for adjustment measures:
- After passing the engine running. Usually, running-in lasts for burning 4-5 litres of fuel.
- When a fuel mixture of different composition is poured into the tank, that is, the type of oil (even it’s colour) and the brand of gasoline change
- When weather conditions change, however, this is more relevant for chainsaws, gasoline generators and motor-pumps, which are operated not only in summer but also in winter.
- If trimmer not used for a long time. The reason for the need to adjust may be a winter break.
- When fuel consumption increases
- If black soot is detected on the spark plug electrodes
- In the absence of the receipt of gasoline in the cylinder or a poor start
- Upon detection of a large amount of exhaust gases
- Unstable engine operation, as well as its difficult start and “sluggish” set of revolutions
As you can see, the reasons for adjusting the trimmer carburetor enough. Usually, artisans who work with the instrument for a long time, by ear, discover changes in the motor’s work, which promises the need for an adjustment process. Even if you are not sure of the need for adjustment work, their extraordinary performance will not be superfluous.
Adjusting the carburetor on trimmers. setup instructions with step by step description.
The process of adjusting the carburetor Trimmer 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 — preferably, but not necessarily
- Check the candle and clean it if necessary, measure the gap and replace. Do not forget that candles have their resource, and are consumables. Sometimes the unstable operation of the internal combustion engine may be associated with the malfunction of the spark plug.
- Check whether the carburetor is properly attached to the cylinder-piston group, as the mounting very often weakens (or the gasket is worn out), which leads to air leakage or primer. After tightening and replacing the gasket, the carburetor may not even need to be adjusted.
- Check the serviceability of the coupling adapter, which stands between the carburetor and the CPG
- Clean the air filter or replace it. It all depends on the state of the filter element. If the element is serviceable, the filter can be washed in soapy water, then dried, and continued operation.
- Fasten the coil or cutting knives in the tool spindle. Adjustment is carried out under load, even if insignificant
When all the preparation points are completed, proceed to the immediate process of setting the carburetor. First, you need to start the engine and let it work for 5-10 minutes, depending on the ambient temperature. When starting the motor on the twentieth, the coil or knives on the trimmer should not rotate. If they move, then it is necessary to reduce the idling speed. The photo below shows an example of the location of the adjustment screws that are used for tuning.
Using a slotted or Phillips screwdriver, proceed to the direct process of tuning work. To begin with, we identify the number of screws to adjust, since there may be 2 or 3, depending on the manufacturer of the tool. Chinese trimmers are usually equipped with two screws.
Below we consider the process of adjusting the carburetor, which has three tuning screws:
- The regulator is labeled L. with it you need to start tuning manipulations. Rotate the screw is necessary when the motor is running. This screw is responsible for the enrichment of the mixture at low revs, so it should be screwed to reach the maximum value. Usually, this bolt rotates until it stops, and then loosens by ¼ turn. When failures are found, it is necessary to tighten the bolt to the stop again and loosen it by 1/8.
- The screw with marking T or LA. with its help adjustment of idling is carried out. Rotation of the bolt in the right side (twisting) helps to increase idle, and to the left decrease. When the speed of the twentieth-century increase, it means that more air is added to the combustible mixture. The mixture is depleted, and power or thrust is lost. Low revolutions in the twentieth say about the excess air in the mixture, so you need to find a middle ground. The adjustment must be made so that the engine of the gasoline mowers stably worked at the XX, and at the same time, the fishing line reel or steel cutting disc did not rotate. The rotation of the cutting elements contributes to the rapid wear of the clutch
- Screw labeled H. this screw is responsible for setting the combustible mixture at high revs. It is with this screw that the tuning manipulations end. The maximum speed value is indicated in the technical description of the tool. To determine the maximum speed as accurately as possible, you should use a tachometer. If there is no tachometer, then the setting is performed by ear. As soon as the maximum speed is reached by ear, the valve must be turned back half a turn (counterclockwise). Bolt H is responsible for power, temperature and fuel consumption.
Often it is precise with the setting of maximum speed difficulties arise. To prevent this from happening, the following actions are performed:
- Pressing the gas, you need to rotate the screw until you reduce the speed (clockwise or to the right)
- After reducing the speed, it is necessary to rotate the bolt like this (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 the ICE operation is smooth.
- The adjustment process is now complete.
If the adjustment work is done correctly, the tool will work stably, the cutting element will not rotate at idle, 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, Chinese gas-powered tools, as well as household appliances, are equipped with two screws.
Summing up, it should be noted that you can not understand the principle of operation of the membrane carburetor trimmers. It is essential to have a screwdriver and tachometer for tuning. However, in order not only to adjust but also to understand what you are doing, it is necessary to know the design and principle of operation.