Now we remove the membrane. It is she who performs the function of pumping fuel into the carburetor..
When the membrane vibrates, the other side exerts pressure on the rocker of the mechanism and the needle rises, which, in turn, opens the hole and the fuel is supplied.
They have the ability to wear out during operation. From prolonged use, they deform, stretch, lose elasticity, poor-quality fuel corrodes them, and can no longer perform their functions well. This also applies to the needle itself. The fact is that it is covered with a thin layer of rubber, which wears out during operation and can no longer fit tightly into the hole. the lawn mower starts to work intermittently. To eliminate such a breakdown, it is necessary to replace all worn out parts. Where to get them?
It includes two diaphragms, a gasket, a needle valve and a spring.
All wear parts of the carburetor can be replaced. Therefore, you should not rush and buy a new one, and you do not need to run to the workshop either, repairs are within the power of any lawn mower user. Professionals claim that the quality of the components in the repair kit even exceeds the characteristics of the native carburetor parts. Therefore, a well-repaired unit will perform better than a new one..
Instruction for Chinese
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 work is performed once after ten minutes of engine operation, however, many Chinese-made models require special handling..
Chinese Chainsaw Model
- 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, you need to adjust the extreme screws to the optimal position so that the chain remains stationary..
- The transition to average speed turns is carried out. Sometimes the engine will smoke. This defect can be eliminated by tightening the screw to supply a leaner fuel mixture..
In this case, the smoke will disappear, but the engine speed will increase. It is necessary to adjust the settings until the level is reached when, when you press the throttle, the engine smoothly picks up speed, no sudden jerks or interruptions are heard.
Take a good look at
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”).
Fuel supply adjustment at minimum speed
Before starting tuning the carburetor of the petrol trimmer, it is required 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 the screw “L” until the start of intermittent operation or until it stalls. Next, unscrew the screw ¼ of a turn and check the speed of the set of maximum revolutions. 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 twisted clockwise, but there are trims where the decrease and increase in the supply of the mixture occurs in the opposite order..
Problem 2: Clogged fine filter
It is located on the carburetor cover and is a fine metal mesh. Its pollution occurs very often. This is due to the deposition of oil, additives, dirt on it.
Diy lawn mowers carburetor adjustment
Periodic adjustment of the trimmer carburetor should be performed on a serviced and fully serviceable power unit. Before starting the procedure, the operator must thoroughly rinse the internal combustion engine parts and inspect its CPG for burrs or other defects. In addition, you will need to clean or change the spark plug, as well as rinse the filter elements in the lawn mowers structure..
The lawn mower engine must be running under a certain load when adjusting the carburetor. It is best to install a cord of the appropriate diameter or cutting knives on the trimmer..
After installing the cutting elements, the operator should start the internal combustion engine of the trimmer and leave it to work for about 10 minutes. If, during the operation of the power unit at idle, it was noticed that the cord or knife rotated, then it is necessary to reduce the speed generated by the motor. To do this, turn the lower adjuster, often marked with the letter “T”, to the left, until the installed cutter comes to a complete stop..
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 when the engine is running at low revs. The position of this screw must be adjusted first. To do this, the operator will need to achieve maximum engine speed when idling – to do this, turn the screw “L” one by one to the right or left. As soon as the maximum speed is reached, the screw will need to be turned 1/2 turn to the left;
- The screw “T” or “LA” is required to adjust the idle speed. While turning it to the left, the speed of the power unit will decrease, and when turning to the right, accordingly, it will increase;
- The regulator “H”, provided on the left, is responsible for enriching the fuel mixture with air when the internal combustion engine trimmer is running at high rpm. This screw is also needed to adjust the engine power and the amount of fuel consumed. Its position is adjusted by turning the screw to the right or left side until the maximum permissible engine speed is reached. After that, the screw “H” will need to be turned 1/2 turn to the left.
Performing these steps one by one will allow you to correctly configure the fuel trimmer assembly, without the risk of exceeding the permissible load on its main working mechanisms..
The trimmer does not belong to complex household appliances, therefore, most of its breakdowns are mechanical in nature and are quite successfully eliminated with their own hands. Even if the engine fails for serious reasons – damage to the piston ring, for example, repairs are reduced to replacing a part.
But even with a relatively simple design, such a part of the device as a carburetor needs to be adjusted..
A carburetor is a power system module in which liquid fuel and air are mixed before being fed into the engine cylinders. Mixing and flow are adjusted accordingly depending on the tool and its mode of operation..
The carburetor device for lawn mowers is the same for almost all cases. It belongs to the category of float devices. The latter provide stable parameters of ready-made mixtures.
The principle of the module is as follows.
- Air enters the body of the air damper tube. The latter increases or decreases the air flow depending on its position..
- In the area where the hole for the gasoline supply is formed, the tube has a narrowing – a diffuser. Here the flow rate increases.
- Fuel from the float chamber is fed through the nozzle into the tube. The float level determines the amount of fuel supplied. Since the pressure in the chamber is normal, and in the tube it is low due to the greater rarefaction of the air, gasoline is sucked in through the nozzle.
- The accelerated air flow picks up the fuel and atomizes it, forming an air-fuel mixture of the desired density.
- The mixture is sucked into the cylinder through the pipeline.
The more open the air damper in the tube, the higher the density of the air flow, and, therefore, more fuel enters the cylinder. Adjusting the carburetor of lawn mowers is reduced to setting such a ratio of flaps, at which the density of the fuel mixture becomes optimal.
From personal experience
First you need to carry out maintenance – clean the candle from carbon deposits, adjust the gap. Then you need to remove and clean the air filter from dust and dirt.
Next, you need to adjust the idle speed – so that the air damper opens almost completely, leaving a slight free play of the cable.
After that, we put back the candle and the filter, and we are already adjusting the gasoline supply screw and the idle screw.
For more information on how to adjust and maintain the carburetor on lawn mowers, see the video below. The review was prepared on the basis of the author’s video from the YouTube channel “Pogranets 13”.
The 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..
Fine tuning the carburetor
If the engine starts, but stalls, then it is necessary to adjust the idle screw. If the revolutions are high – unscrew the screw, closing the air damper.
How to adjust your idle screw on your Husqvarna 128LD
In the event that the revolutions, on the contrary, are small, then we tighten the screw, opening the air damper. “Playing” with this screw, you can achieve optimal parameters of the engine at idle.
If the engine stalls directly during operation (when you mow the grass), then you need to re-adjust the gasoline supply screw. Unscrew or tighten this screw until we achieve the desired result.
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 locking nut and screw in the screw to decrease the maximum speed or turn it to increase. Tighten the nut after adjustment. The maximum RPM setting 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 the screw another quarter turn. If starting is difficult, increase idle speed. Both weather conditions and the quality of the fuel mixture can affect the operation of lawn mowers. Vibration can cause the adjusting screws themselves to turn..
Fuel supply adjustment
Start slowly tightening 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 did not stall, 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 the screw 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 the lawn mower can be the other way around.
In the worst times of trimming with an unadjusted carburetor, the engine would stop starting after every tank of fuel was used. And only after cleaning the spark plug from carbon deposits it was possible to continue working..
* Husqvarna 128ld trimmer carburetor adjustment carb
Fine sandpaper was used to clean the electrodes, and a thin paper clip with a bent end was used to clean the space between the insulator and the body. First, the electrodes were wiped from large dirt with a rag, then they were smoothed with sandpaper. After that, the candle was dipped into diesel fuel and the moistened carbon was scraped off with a paper clip from the surfaces of the insulator, the inside of the body and between them. Then the candle was dipped several times into the diesel fuel, which was then shaken off it along with the dirt. Sometimes the paper clip cleaning and rinsing procedure was repeated. After that, the candle was wiped dry and was ready for further use..
Incredibly, one tank of the fuel mixture with an unregulated carburetor can be used up in less than 10 minutes – tested in practice when the trimmer was started and operated at high speeds with maximum fuel supply (the adjusting screw was unscrewed much more than normal).
Other articles on this topic:
Lubrication of the shafts of lawn mowers, trimmers
To prevent the petrol trimmer (lawn mower) from junk during operation, you need to properly adjust the carburetor. Well, you shouldn’t forget about periodic maintenance either..
In this review, we will look at the main nuances that a beginner who first bought a gasoline trimmer needs to know..
Idle speed adjustment
We start adjusting low speed. The screw limits the return movement of the throttle lever – by turning it, we increase the idle speed, unscrewing it, we decrease it. Adjust so that the engine runs confidently at low revs and even slightly accelerated (for better starting), but so that the line reel or knife does not rotate, and there is a sufficient reserve of revolutions before they start spinning. If the engine starts poorly, increase the idle speed even more..