The trimmer does not belong to complex household appliances, so most of its breakdowns are mechanical in nature and can be successfully repaired with their own hands. Even if the engine fails for serious reasons. damage to the piston ring, for example, repair comes down to replacing the part.
But even with a relatively simple design, such a part of the device as a carburetor needs to be adjusted.
Principle of operation
A carburetor is a power supply module in which liquid fuel and air are mixed before being fed into the engine cylinders. Depending on the tool and its operating mode, mixing and feeding are adjusted accordingly.
The carburetor device for lawn mowers is the same in almost all cases. It belongs to the category of float devices. The latter provide stable parameters of the finished mixtures.
The principle of operation of the module is as follows.
- Air enters the body of the tube with an air damper. The latter enhances or reduces airflow depending on its position.
- In the area where the hole for supplying gasoline is formed, the tube has a constriction. a diffuser. Here the flow rate increases.
- Fuel from the float chamber through the nozzle is fed into the tube. The float level determines the amount of fuel supplied. Since the pressure in the chamber is normal and low in the tube due to the greater dilution of air, gasoline is sucked through the nozzle.
- Accelerated airflow picks up fuel and atomizes it, forming an air-fuel mixture of the desired density.
- The mixture is sucked into the cylinder through a pipe.
The more open the air damper in the tube, the higher the density of the air flow, which means that more fuel enters the cylinder. Setting the carburetor of the lawn mowers is reduced to setting such a ratio of dampers at which the density of the fuel mixture becomes optimal.
Signs of imbalance
Carburetor debugging is necessarily carried out in the manufacture of the apparatus. As a rule, the owners will only learn about the need to adjust the fuel supply themselves after serious failures, during the correction of which the module was removed and, for example, cleaned.
Signs of a failure in the settings are as follows:
- it starts, but the engine stalls right away. since the engine can only work when a certain amount of gasoline is supplied, if the fuel is too “poor”, that is, when the feed channel is blocked, the motor will stop;
- too much fuel consumption, a lot of exhaust gases. the result of incomplete combustion of the mixture. In this case, on the contrary, there is too much fuel and the mixture turns out to be excessively dense.
DIY carburetor adjustment
The configuration of the module does not apply to repair and replacement of spare parts is not required. In this case, a repair kit for the carburetor lawn mowers will not be needed.
There are three screws for debugging:
- L. is regulated first, since it is responsible for supplying fuel at low speeds;
- H. he is responsible for the supply of gasoline at high speeds, as well as for fuel consumption and temperature;
- T. with its help, idle debugging is carried out.
There are options, as a rule, this is a Chinese lawn mowing carburetor, when there is only one screw left for debugging on the case. to adjust the idle speed. This does not mean that the module is automatically configured. it means that even a type of repair such as debugging will be difficult. In the photo. carburetor adjustment of the Chinese lawn mowers.
- Setting up the module is carried out only when the engine is warm: for this, the device is first turned on for 10 minutes. If the mowing head rotates at idle, then proceed with debugging immediately: turn screw T counterclockwise until the rotation stops.
- Adjustment starts with screw L. The screw rotates left and right until it finds its position at which idle speed does not become maximum.
- Then turn the screw на turn counterclockwise. This will be his working position.
- Idling must be adjusted by turning counterclockwise to increase the speed and clockwise to decrease. Its debugging consists in achieving such a mode in which a sufficient number of revolutions is made before the mowing head begins to rotate. In this case, the engine must work stably in different positions.
- The position of the screw L is determined last. at maximum speeds the trimmer should not work for more than 10 seconds. The throttle opens, the screw rotates clockwise, very slowly, until a decrease in the number of revolutions is established by ear.
- Then, the screw also rotates slowly counterclockwise until the motor starts to malfunction. Then the screw is turned back clockwise until the engine starts working again normally.
If there is a tanometer, and if the recommended revolutions are indicated in the product passport, the correction can be made more accurate, focusing not on the ear, but on the readings of the device.
The adjustment of the carburetor of the lawn mowers on the video was carried out by ear.
Video: How To Adjust A Carb On A Patriot Trimmer
7 comments on the post “Adjustment and repair of the carburetor of the lawn mowers”
- Dmitry Pavlovich 07/04/2016
Please clarify. In the adjustment section 5, screw L. error? Should I read screw A? Thank you
tell me the initial position of the screws H L LA
TIP THE INITIAL POSITION
tell me the initial position of the screws H L LA
Thank you very much for the video about the accelerator and I don’t know, and the defect is very important and creates a huge problem about which almost everyone is silent. BRAVO….
Maybe all the same, a tachometer is a speed meter, and not a tonometer, a blood pressure meter
and I have L, H, LA, is it LA instead of T?
The heart of any chainsaw is a two-stroke internal combustion engine.
The trimmer does not apply to complex household appliances, so most of it is gender.
There was a need to purchase a reliable and faithful mechanical aids.
Gone are the days of the Soviet agro-industrial gigantomania. They made a gig.
the tiller is an economical tractor option for small jobs.
In order to make such a nozzle as a harrow, with your own hands, in addition to ph.
The increased fuel consumption and the rapid formation of soot on the lawn mowing candles when using a correctly prepared fuel mixture indicate the need for carburetor adjustment. This describes how to set trimmers with carburetors that have one screw for adjusting the fuel supply.
Flush the air filter before adjusting the carburetor. It is recommended to rinse it after every 10 hours of operation. After that, you can begin to adjust. The example photograph shows the carburetor of the gasoline trimmer PRORAB-8406. The numbers indicate the adjusting screws that we will use.
PRORAB-8406 gas trimmer carburetor adjusting screws
Purpose of adjusting screws:
- Fuel mixture adjusting screw.
- Idle adjustment screw.
- The screw limits the maximum speed.
Start the lawn mower and wait until it warms up.
Start slowly tightening the fuel mixture adjusting screw until the engine stalls or stalls unless you catch the moment. Then unscrew the screw a quarter of a turn if the engine is not dead, or half a turn if it is dead. Start the stalled engine. Check, by opening the throttle, how the engine accelerates. Continue to loosen screw # 1 a quarter of a turn until the engine starts to confidently gain high revs when progazovka. This will be the moment of the most economical stable engine operation. At the PRORAB-8406 gas trimmer, the adjusting screws are turned clockwise, unscrewed. against, for some other brands the lawn mowing may be vice versa.
We proceed to adjust the low speed. Screw number 2 restricts the return movement of the throttle lever. by wrapping it, we increase idle speed, unscrewing. reduce it. Adjust so that the engine runs confidently at low speeds and even slightly faster (for a better start), but so that the reel with fishing line or knife does not rotate, and before starting to rotate, there is a sufficient margin of speed. If the engine starts poorly, still increase idle speed.
Maximum speed limit
After adjusting the flow of the fuel mixture and low revs, check how the lawn mowing engine will operate at maximum speed. If necessary, limit the maximum speed to the required level using the No. 3 hollow screw. Loosen the locking nut and screw in to decrease the maximum speed or unscrew to increase. After adjustment, tighten the nut. Setting the maximum speed is necessary to protect the trimmer motor from overheating and the ability to use the release key lock to reduce fatigue of the right hand.
In the future, it may be necessary to adjust the trimmer carburetor. For example, if the engine, when operating at full load, starts to pick up revs poorly, loosen screw No. 1 another quarter of a turn. If it is difficult to start, increase the idle speed. Weather conditions and the quality of the fuel mixture can affect the operation of lawn mowers. The vibration can also make the adjusting screws turn themselves.
The spring may interfere
My first attempt to adjust the carburetor of the lawn mowers did not work, as the spring of the fuel mixture adjustment screw prevented it. The factory spring turned out to be too thick in a compressed state and did not give the opportunity to reduce the fuel supply to the required level. I had to pick up another spring and continue adjusting after replacing it.
Spring mixture adjustment screw
In the photo above, the factory spring, below the adjustment screw with a selected spring. I am writing about this, because I’m not sure that this is an isolated case, and someone else may encounter the same situation.
From personal experience
lawn mowing or trimmer
A trimmer is a broader concept than a lawn mow (lawn mow), since it can also be electric. A gas trimmer and a lawn mower are one and the same.
Some authors claim that the trimmer is a weaker tool, in contrast to the more powerful lawn mowers, which can be used to mow shrubs. Personally, I have a tool with a maximum power of 1.7 kW and capable of mowing a small shrub up to 10 mm thick, as stated in the instructions. The user manual is called “Petrol trimmer.”.
Fuel mix ratio
I read somewhere that if in the instruction manual for lawn mowers and on the canister with oil different proportions of the preparation of the fuel mixture are indicated, the proportion indicated in the manual should be used.
It did so for a long time. excess oil flowed from the engine to the gas tank and soot was constantly forming on the candle, since the manual indicated the proportion for the engine being run in 1:25, and on the canister. 1:50. After the transition to a proportion of 1:50, the appearance of oil drips stopped. The candle continued to burn, but with less intensity (the carburetor was not yet adjusted).
Until now, some users of gasoline tools determine the proportion of the fuel mixture “by eye”. If during the preparation of the mixture the amount of oil is underestimated, after some time an extraneous sound may appear immediately after the engine starts, gradually disappearing during warming up, and the engine stops with a sharp jerk. Continued operation of the trimmer in this mode will lead to its failure.
In the worst days of working with a trimmer with an unregulated carburetor, the engine stopped starting after using each fuel tank. And only after cleaning the candles from soot could we continue to work.
To clean the electrodes, fine sandpaper was used, and to clean the space between the insulator and the body, a thin clerical clip with a bent end was used. First, the electrodes were wiped off with a lot of dirt with a rag, then they were cleaned with sandpaper. After that, the candle was lowered into diesel fuel and the moistened soot was scraped off with a paper clip from the surfaces of the insulator, the inside of the housing and between them. Further, the candle was lowered several times in diesel fuel, which was then shaken off from it along with impurities. Sometimes the cleaning procedure with a paper clip and washing are 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 consumed in less than 10 minutes. it was tested in practice when the trimmer was started and operated at high speeds with maximum fuel supply (the adjustment screw was unscrewed much more than normal).