Throttle and choke shaft wear
The air and throttle shaft can wear out for the following reasons:
- Insufficient and incorrect maintenance of the air filter;
- The air filter is damaged;
- The air filter is not suitable for this unit.
Due to the ingress of poorly cleaned air, the shaft wears out and may break. Broken shaft parts can enter the combustion chamber or crankcase and cause serious damage to the entire piston system.
To eliminate problems with air purification, it is necessary to replace the defective filter or flush the existing (serviceable) one. The filter must be washed in soapy water and dried.
Clogged mesh filter
The strainer can become dirty if contaminated fuel enters through a fuel hose or a defective pickup head. In the photo below you can see what a clean filter looks like and a dirty one (parts are separated by a line).
To eliminate the malfunction, thorough cleaning and rinsing of the mesh filter will be required. It is also recommended to blow compressed air through all holes in the carburetor trimmer housing.
Adjustment lever defective
This breakage occurs when the contact surface of the lever wears out.
The abrasion of the contact surface occurs due to the presence of abrasive particles in the gasoline or due to strong vibration of the engine during operation. This defect in the adjusting lever causes problems with the intake, as well as improper idling of the engine.
Clogged control cavity
If dirt accumulates in the adjustment cavity, then the inlet needle cannot close the hole tightly and a lot of fuel pours into the chamber.
This causes the fuel to over-enrich and the engine starts to malfunction. It is necessary to disassemble the carburetor and clean the cavity of the control membrane.
Common carburetor malfunctions
Failure of the trimmer carburetor occurs due to the use of poor quality gasoline, a damaged air filter and the accumulation of dirt in the chamber of this unit. Most often, it is quite possible to repair the carburetor with your own hands. Listed below are typical lawn mowers carburetor malfunctions.
Intake needle wear
The inlet needle fails, as a rule, due to the presence of abrasive particles in the fuel fluid.
- The tightness of the inlet needle seat is disrupted;
- There is a leakage of a combustible mixture;
- There are malfunctions in the engine, associated with re-enrichment of the fuel mixture.
Also, the inlet needle may just jam.
A jammed inlet needle can cause dirt in the fuel or long idle times.
Fuel pump problems
A common malfunction that “pursues” the fuel pump is the deformation of the pump membrane. For this reason, It does not fit properly and the pumping passages are NOT sealed.
The reasons for membrane deformation can be the following:
- Long work of the trimmer;
- Use of unusable fuel;
- Ingress of gases into the impulse channel.
As a result, diaphragm damage Reduces pump performance, and as a result:
- The fuel mixture is depleted;
- Difficulty starting the engine;
- There are interruptions in the operation of the motor;
- The piston is damaged.
Also, the above-described consequences for the motor can cause clogging of the pump cavity on the impulse side. In this case, dirt enters the membrane through the impulse channel.
To remove the blockage, you will have to disassemble the carburetor and clean the membrane.
The throttle and choke valves are mainly subject to wear due to the presence of abrasive particles in the air. Defective flaps look like they have been sandblasted.
As a result of valve wear, engine performance decreases, malfunctions appear in its operation, piston rings, piston and cylinder coating wear out.
How to properly adjust the trimmer carburetor
In addition to electric motors, the trim tabs are fitted with gasoline internal combustion engines. This mechanism requires special attention to itself, since if it is incorrectly configured, it will either refuse to work, or it will work intermittently and loss of power. Basically, engine tuning is about adjusting the fuel flow, and this is done using the carburetor trimmer.
How to reduce the speed of coolers
One of the ways to make the computer less noisy is to reduce the speed of the fans (coolers) inside the system unit.
This problem can be solved by using Special programs, installing devices in the computer that reduce the speed of coolers, or by a combination of the two mentioned methods.
At the same time, the issue of reducing noise must be approached wisely, since lowering the fan speed causes an increase in the temperature of the computer’s internal devices. This can negatively impact their performance and longevity. It is important to find a balance between a comfortable noise level and an acceptable temperature for the computer.
But before that it is necessary:
Install programs on the computer that allow you to control the temperature of its main “heating” devices, namely:
Speed Fan. A program that allows you to control the temperature of all computer devices in real time;
Prime 95. A program that creates a high load on the central processor. Allows you to check the stability of the processor and the efficiency of its cooling system in extreme conditions. Read more about checking the processor using this program here.
Furmark. Program for testing the graphics system of a computer. It creates an increased load on the card, while controlling its temperature and stability.
Using these programs, check the temperature conditions of the processor, card, hard disk and chipset of the computer motherboard.
In most cases, under maximum load, the temperature of the hard drive should not exceed 45 degrees C, the processor and motherboard chipset. 60 degrees C, maps. 85 degrees C.
It is possible to “load” the hard drive without Special programs, for example, by starting the process of archiving or copying a large file on it (movie, disk image, etc.).
If the temperature of a device turns out to be close to the above indicators, you should not reduce the speed of the cooler cooling it.
In the case when the maximum performance is still far away, the fan speed can be reduced using the methods described below.
IMPORTANT. After reducing the speed Do not forget to check the temperature of the devices cooled by coolers. Do not overheat them. Remember that prolonged use of the computer in adverse temperature conditions will reduce its durability.
If the computer used to work quietly and only recently began to create a lot of noise, it is likely that the problem can be solved simply by cleaning the system unit from dust. You may also need to lubricate the coolers. Read about it here.
In some cases, it is possible to improve processor cooling and significantly reduce the noise of its fan by replacing the thermal paste.
If the above actions did not solve the problem, you can reduce the rotation intensity of one, the most “noisy”, or several fans in the system unit.
Reducing the speed of coolers via BIOS
(This method most often manages to lower only the speed of the CPU cooler)
The procedure is as follows:
Go to the BIOS settings of the computer.
Read about what BIOS is and how to change its settings here.
Find there the “CPU Fan Speed” parameter or with another very similar name. It is usually located under “Hardware Monitor” or “Power”.
Set the “CPU Fan Speed” item to a suitable value. The most common options available are:
“Turbo”. Assumes improved cooling due to the maximum fan speed;
“Standart”. Normal cooling mode;
“Silent”. Minimum Possible fan speed.
We choose the last option. To save the changes, press the “Esc” key, then. “F10” then. “Enter”.
Reducing the speed of coolers using programs
(The method is suitable for coolers of the processor and card; in some cases. For coolers of the case of the system unit)
The Speed Fan program is a universal tool. For the link to the download page, see the Preparation section above. It allows you to change the rotational speed of most fans of the system unit, if this feature is supported by the motherboard.
For computers with an ASUS motherboard, the ASUS AI Suite program is suitable (you can download it on the official ASUS website). It allows you to specify the dependence of the fan speed on the temperature of the processor and other devices.
For GeForce series cards, we recommend nVidia Inspektor.
The program does not require installation. After starting it, press the “Show Overclocking” button, in the appeared dialog box, press the “OK” button. The panel for changing map parameters will open.
To adjust the rotational speed of the cooler, uncheck the “Auto” item above the “Set FAN” button, then select the required value, move the vertical slider located next to it. You can set any fan intensity in the range from 25% to 100%. For the new values to take effect, you must press the “Set Fan” button.
There are other similar programs that are not difficult to find on the Internet.
At the same time, many computers DO NOT support software control of the speed of coolers, or this possibility is very limited. In such cases, the problem is solved by purchasing and installing devices in the system unit that change the supply voltage of the fans.
Reducing the speed of coolers
using special devices
There are several types of devices that reduce the rotation rate of coolers:
Additional resistance device without speed control. It is a regular resistor soldered into the cooler’s power circuit.
Adjustable resistance device. Unlike the device of the first type, it allows you to “manually” change the speed of the fan connected through it (there is a special regulator on it).
This device is mounted inside the system unit, which is not very convenient, because to change the fan speed, you need to open the computer case every time.
Reobass, which is an improved version of the previous device.
Reobassom allows you to adjust the intensity of 3 or more fans (depending on the model). It is installed in the computer case so that the user can constantly change the speed of the coolers connected to it (usually on the front panel of the system unit, in the cell for DVD drives).
Devices that reduce the speed of coolers. The tool is more versatile and reliable than the programs mentioned above. They can be used in any computers and for any fans.
Their main drawback. The need to spend money on their purchase. At the same time, this money is not so big. For example, the cheapest reobasom will cost US 20-25. The cost of the first two types is much lower.
How the trimmer ignition system works
The ignition system of a two-stroke internal combustion engine consists of 2 parts: a flywheel and a coil (magneto). The picture below shows how they look.
The flywheel has an impeller that acts as a fan to cool the engine. Also on one side of the flywheel are permanent magnets, shown in the figure by an arrow.
When the flywheel rotates, an electric current is generated in the coil, which serves to produce a spark on the spark plug. A spark appears when the magnets are directly below the magneto.
Ignition adjustment for trim tabs
On gasoline trimmers, both two-stroke internal combustion engines (ICE) and four-stroke are used. But the ignition system in them is NOT different from each other, therefore, the repair and adjustment of this fuel ignition system will be the same for different types of internal combustion engines.
Why do I need ignition adjustment
In some cases, when the engine will NOT start, ignition adjustment will be required. Of course, first you need to check the condition of the candle and the high-voltage cable with a cap.
It is necessary to adjust the ignition on a two-stroke engine in order to ensure timely ignition of the fuel in the engine combustion chamber. Below is a diagram from which you can understand the principle of operation of the internal combustion engine.
The spark in the spark plug should appear at the moment the fuel is compressed by the piston, when it does not reach the top dead center (TDC) just a little. When the piston passes TDC, the fuel mixture ignites, as a result of which the piston goes down under the action of the explosion energy.
Therefore, if for some reason (this is mainly due to the displacement of the flywheel on the shaft until its initial position), the fuel ignites before the piston passes TDC, then it goes back, and the crankshaft rotates in the opposite direction. This movement can damage the starter assembly, cut the starter cord, etc. In this case, early ignition of the fuel occurs.
There may also be a late ignition on the trimmer: the piston, after compression of the fuel, which has not ignited, goes down, and at this moment a spark appears. In this case, the engine will either not start, or will significantly lose power and gain speed poorly.
But such problems with early or late ignition on two-stroke internal combustion engines are quite rare, since the flywheel with magnets is already installed in the correct position, which is perfectly synchronized with the movement of the piston. In addition, the flywheel is secured to the shaft with a key and nut. Therefore, incorrect installation of the part is excluded.
How to check the health of a magneto
Magneto is the main part of the engine ignition system and is a coil with primary and secondary windings located around the core. Often, due to a malfunction of the magneto, the spark on the spark plug disappears and the fuel does not ignite. To check the coil, you need to use a tester, and follow these steps.
- On testers, go to the resistance measurement mode, you need to set 200 ohms. This method will check the primary winding.
- Connect one electrode of the tester to coil ground and the other to the lead coming out of the magneto. Normally, the resistance should be between 0.4 and 2 ohms.
- To check the secondary winding, you need to set the device switch to 20 kOhm. Further, one probe of the device is inserted into the candle cap, and the second is connected to the “mass”. Normally, resistance indicators should be in the range of 4-6 kΩ and above (depending on the model).
If you have a tester, then you can use the following method; it is very careful so that the electrode does NOT touch the cylinder, otherwise the coil will burn out.
- Remove the cap from the candle. It is not necessary to unscrew the candle in order to maintain compression.
- You must insert a nail into the cap without a cap. The nail should be of such a diameter that it holds well in the cap.
- Tie the cap with a nail to the cylinder, Using a dielectric, so that the gap between the electrode and the cylinder body is in the range of 5.5 to 7 mm (but in no case touches the “mass”).
- Using the starter Let’s simulate the engine start several times. The ignition button must be on.
- Observe if a spark appears and what color it has.
Normally, the spark should be strong, white or bluish in color. If the spark is weak, and its color is orange or yellow, this indicates a faulty magneto.
Also consider the fact that sometimes cold magneto can give a good spark. But after heating, due to internal faults, it ceases to produce current. As soon as the coil cools down, the trimmer starts again and runs for a while until the magneto does NOT heat up again. This coil needs to be replaced.
Ignition adjustment algorithm
Trimmer ignition is quite simple to adjust.
- Remove the engine cover from the engine by unscrewing all the bolts holding it. For example, on Patriot (Patriot) PT 2540 lawn mowers, to remove the cover, you will need to Unscrew the air filter housing, and remove it from the latches with a flat screwdriver. After that, the plastic case can be easily removed.
Fuel supply adjustment
Start slowly tightening the fuel mixture adjustment screw until the engine does NOT start to stall or until it 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 loosen screw a quarter of a turn until the engine does NOT accelerate steadily when bumping. This will be the moment of the most economical stable operation of the engine. In the PRORAB-8406 petrol trimmer, the adjusting screws are turned clockwise, unscrewed. against, for some other brands of lawn mowers it may be the other way around.
Spring may interfere
My first attempt to adjust the carburetor of the lawn mowers did not work, as the spring of the fuel adjustment screw interfered with. The factory spring turned out to be too thick in the compressed state 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.
Fuel mixture adjusting screw with spring
In the photo above the factory spring, below the adjusting screw with the selected spring. I am writing about this because I’m not sure if this is an isolated case, and someone else may encounter the same situation.
Lawn mower or trimmer
A trimmer is a broader concept than a lawn mower (lawn mower), as it can also be electric. A petrol trimmer and a lawn mower are one and the same.
Some authors claim that the trimmer is a weaker tool than a more powerful lawn mower, which can be used for mowing shrubs. Personally, I have a tool with a maximum power of 1.7 kW and is capable, as stated in the instructions, to mow small bushes up to 10 mm thick. The user manual is called “Petrol trimmer.”.
From personal experience. Carburetor adjustment
Before adjusting the carburetor, flush the air filter. It is recommended to rinse it after every 10 hours of operation. After that, you can start adjusting. The photo shows a PRORAB-8406 petrol trimmer carburetor for example. The numbers indicate the adjusting screws that we will use.
PRORAB-8406 petrol trimmer carburetor adjusting screws
Purpose of adjusting screws:
- Fuel mixture adjustment screw.
- Idling adjustment screw.
- Maximum speed limiting screw.
Start a lawn mower and wait for it to warm up.
Maximum speed limitation
After adjusting the fuel mixture and low speed, check how the lawn mower engine will run at maximum speed. If necessary, limit the maximum speed to the required level using the hollow screw. Loosen the fixing nut and screw in the screw to decrease the maximum speed or unscrew it for growth. After adjustment, tighten the nut. Setting the maximum RPM is necessary to protect the trimmer motor from overheating and to be able to use the start key lock to reduce right hand fatigue.
In the future, it may be necessary to readjust the trimmer carburetor. For example, if the engine starts to rev poorly when running at full load, loosen screw another quarter turn. If starting is difficult, increase idle speed. Both the weather conditions and the quality of the fuel mixture can affect the operation of lawn mowers. Here vibrations can turn the adjusting screws themselves.
Adjusting the carburetor lawn mowers, trimmer
Increased fuel consumption and rapid formation of carbon deposits on the spark plug when used correctly. A properly prepared fuel mixture indicates the need to adjust the carburetor. Here’s how to adjust trims with carburettors with one fuel adjusting screw.
I read somewhere that if different proportions of preparation of the fuel mixture are indicated in the operator’s manual for the lawn mowers and on the Oil Canister, the proportion indicated in the manual should be used.
For a long time I did just that. excess oil dripped from the engine onto the gas tank and carbon deposits were constantly formed on the candle, 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 up, but with less intensity (the carburetor was NOT adjusted yet).
Until now, some users of gasoline-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 lead to its failure.
Idle speed adjustment
We start adjusting low speed. Screw number 2 limits the return movement of the throttle lever. Wrap it up, we Increase idle speed, unscrewing. decreasing. Adjust so that the engine runs confidently at low revs and even slightly accelerated (for better starting), but so that the reel with the line or knife does NOT rotate, and there is a sufficient reserve of revolutions at the beginning of their rotation. If the engine starts poorly, also increase the idle speed.
The design of the gas trimmer carburetor and its purpose
Lawn mowers are equipped with two-stroke internal combustion engines. A carburetor is used to supply the air-fuel mixture to the engine cylinder. In the design of gasoline units, this is a key element, without which the operation of the internal combustion engine is impossible. over, this carburetor differs from the automobile device Not only in size, but also in the principle of operation. In particular, this difference lies in the presence of a membrane that plays the role of a gas pump. It is due to the presence of a membrane that the considered devices in the design of two-stroke internal combustion engines are called membrane.
Structurally, the entire mechanism is a small piece with channels, valves and diaphragms inside. The carburetor body is made of aluminum, and the internal structure is shown in the photo below.
Before adjusting the carburetor of the lawn mowers with your own hands, you need to deal with all the constituent elements of the device in question. The lawn mower and trimmer carburetor consists of the following parts:
- Diffuser or Venturi nozzle. through this nozzle air is sucked into the system
- Air damper. opens and closes the filtered air supply
- Fuel channel of maximum speed
- Fuel channels (jets) of idle speed XX and medium speed
- Throttle valve. the amount of opening is adjusted by pressing the gas
- Impulse channel fitting. connects to the internal channel of the engine crankcase
- Fuel inlet (union) (2). provides fuel supply from the gas tank
- Membrane (4). is responsible for sucking fuel from the gas tank
- Fuel suction valve (3)
- The valve for supplying fuel to the carburetor channel (5)
- Filter element (6) or fine fuel filter
- Fuel pipe (10)
- The needle of the needle valve (14). is responsible for supplying fuel to the chamber of the control diaphragm
- Chamber. the fuel mixture that is fed through the jets and the throttle valve to the cylinder
- Control diaphragm (18). provides manual fuel suction with primer
- Diaphragm Lever (17)
- Idle speed screw (15)
- The screw for adjusting the amount of fuel supplied to the diffuser (13)
Having an idea of how the carburetor works inside, you have to figure out how it works. A detailed description of how the carburetor works on a two-stroke internal combustion engine using the example of a chainsaw is described in this material.
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 for lawn mowers and trimmers, you need to understand the principle of their operation. How the carburetor works on lawn mowers 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
- The 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 an inlet valve, through which fuel is supplied to the sub-membrane space, and valve 5 is an outlet
- Further, the fuel moves along the channel and, passing through 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 actuated by acting on the diaphragm. When it is necessary to pump fuel in order 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 is started (cold), the opening of the needle occurs due to vacuum with the air damper closed. This vacuum acts through the idle and high speed nozzles on the membrane 18
- The membrane acts through a lever on the needle valve, whereby the chamber is filled
- After starting the engine, the choke opens, causing the engine to run on a lean mixture as fuel mixes with air
- When the chamber is full, the fuel mixture is supplied (sucked in) through the idle and medium speed jets (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 enter 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 pressure on the gas). In all operating modes, the air damper must be open, through which the fuel is mixed with air, and thus the mixture is ignited in the cylinder
Below is a diagram of how the lawn mower carburetor works. Based on the diagram You can not only understand 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 another 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 scuffing 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 \ u200b \ u200bthe design of a membrane carburetor 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 a stable and smooth operation of the internal combustion engine.
The device and adjustment of the carburetor for lawn mowers and trimmers
A lawn mower or trimmer with an internal combustion engine require not only constant refueling 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 lawn mowers, the efficiency and performance of the tool depend on the correct operation of which. If, during operation, a faulty (abnormal) engine operation is detected, then the first step is to adjust the carburetor of the lawn mowers. Before setting up the carburetor of the gasoline trimmer, let’s first understand its design.
How to know if a lawn mower carburetor needs adjustment
Many lawn mowers use lawn mowers for a long time without thinking about the need to adjust the carburetor of the tool. When is it necessary to adjust the carburetor on lawn mowers or lawn mowers? If you are asking such a question, then for sure there are changes in the operation of the motor not for the better. In order not to guess, and will not miss the moment of the need to adjust the carburetor, you should adhere to the following recommendations in the need for adjustment measures:
- After the engine has run in. Usually, the break-in lasts by burning 4-5 liters of fuel
- When the fuel mixture of the second composition is poured into the tank, that is, the type of oil (even its color) and the brand of gasoline change
- When weather conditions change, however, this is more relevant for chainsaws, gas generators and motor pumps, which are operated not only in summer, but also in winter
- If the mower has NOT been used for a long time. The reason for the need for adjustment may be a winter break
- When fuel consumption increases
- If black carbon is found on the spark plug electrode
- In the absence of gasoline in the cylinder or poor engine start
- If a large amount of exhaust gas is detected
- Unstable engine operation, as well as its difficult start and “Sluggish” set of revolutions
As you can see, lawn mowers have enough reasons to adjust the carburetor. Usually, masters who work with the tool for a long time detect changes in engine operation by ear, which promises the need for an adjustment process. Even if you are not sure of the need for adjustment work, then their extraordinary performance will definitely not be superfluous.
Adjusting the carburetor on lawn and lawn mowers. setup instructions with step-by-step descriptions
The process of adjusting the carburetor of a lawn mower or trimmer itself 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. desirable but not required
- Check the spark plug, and if necessary clean it, measure the gap and replace it. Do not forget that candles have their own resource and are consumables. Sometimes the unstable operation of the internal combustion engine can be associated precisely with a malfunctioning candle
- Check whether the carburetor is properly attached to the cylinder-piston group, since the fastening very often weakens (or the gasket wears out), which leads to air or primer leaks. After tightening and replacing the gasket, the carburetor may not even need to be adjusted
- Check the serviceability of the connecting adapter, which stands between the carburetor and the CPG
- Clean the air filter or replace it. It all depends on the condition of the filter element. If the element is suitable for use, then the filter can be washed in soapy water, and then dried, and continue to use.
- Attach the spool or cutting knives to the tool spindle. Adjustment is carried out under load, even if only slightly
When all the preparation points are completed, we proceed to the direct process of setting up the carburetor. First, start the engine, and let it run for 5-10 minutes, depending on the ambient temperature. When starting the motor on XX, the spool or knives on the trimmer should NOT rotate. If they move, then it is necessary to reduce the idle speed. The photo below shows an example of the location of the adjusting screws that perform the adjustment.
Using a slotted or Phillips screwdriver, we proceed to the direct process of adjustment work. To begin with, identifying the number of screws for adjustment, since there can be 2 or 3 of them, depending on the manufacturer of the instrument. Usually Chinese trimmers are equipped with two screws. Below we will consider the process of tuning the carburetor, which has three tuning screws:
- Regulator marked L. you need to start tuning manipulations with it. It is necessary to rotate the screw when the motor is running. This screw is responsible for enriching the mixture at low speeds, so it should be screwed up so that it reaches its maximum value. Typically, this bolt rotates until it stops and then looses turn. If dips are found, it is necessary to re-tighten the bolt until it stops, and loosen it by 1/8
- Screw marked T or LA. this is used to adjust the idle speed. Turning the bolt to the right (tightening) increases the idle speed, and to the left, decreases it. When the speed of XX is increased, this means that more air is added to the combustible mixture. The mixture becomes leaner and power or thrust is lost. Reduced RPM at XX indicates an excess of air in the mixture, so it is necessary to find a middle ground. The setting must be done so that the lawn mower engine runs stably at XX, and at the same time the line spool or steel cutting disc does NOT rotate. The rotation of the cutting elements contributes to the rapid wear of the clutch
- Screw marked H. This screw is responsible for adjusting the fuel mixture at high speeds. It is with this screw that adjustment manipulations end. The maximum speed is indicated in the technical description for the tool. To determine the maximum speed value as accurately as possible, you should use a tachometer. If there is a tachometer, then the tuning is performed by ear. As soon as the maximum number of revolutions is reached by ear, the valve must be returned half a turn back (counterclockwise). Bolt H is responsible for power, temperature and fuel consumption
Often it is with the setting of the maximum speed that difficulties arise. To prevent this from happening, the following actions are performed:
- While pressing the gas, it is necessary to rotate the screw until the speed decreases (clockwise or to the right)
- After reducing the speed, it is required to turn the bolt so (counterclockwise or to the left) in order to detect unstable engine operation
- As soon as this unstable operation is detected, the screw should be returned clockwise until smooth operation of the internal combustion engine occurs.
- This completes the adjustment process.
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. Typically, 2 screws are equipped with Chinese gas powered tools, as well as household units.
Summing up, it should be noted that one cannot but understand the principle of operation of the membrane carburetor for lawn mowers and trimmers. It is important to have a screwdriver and a tachometer for adjustment. However, in order not just to adjust, but also the concepts of what you are doing, it is imperative to know the design and principle of operation.