How to set up a Chinese chainsaw carburetor
How to set up a chainsaw carburetor if it won’t start at all
Quite a common problem in cases when a “master” from the “I know everything” series tries to get into the settings with hands that do not grow from the shoulders. In such a case, there are standard screw positions from which you can “dance” further. First, you need to completely tighten both screws (do not overdo it). Then unscrew:
- screw L. one revolution;
- screw H. one and a half turn.
With regard to the idle screw, the throttle must first be completely closed (screw T unscrewed). After that, it must be cranked one and a half turns clockwise and try to start the engine. If it did not work out, it is gradually added by a quarter of a turn before starting. When the engine starts to work, the position of the idle screw is adjusted so that the internal combustion engine does not stall, but the chain is still in place.
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Determining the need to adjust the carburetor on a chainsaw
Before you start adjusting the carburetor on a chainsaw, you need to make sure that it is generally required. It would seem an absurd phrase. However, in 90% of cases, when an inexperienced craftsman considers such an action necessary, the unstable operation of the instrument is associated with other reasons, including:
- problems in fuel lines and filter. blockages, depressurization;
- malfunction of the exhaust system;
- clogged or damaged air filter;
- unstable operation of the ignition system;
- violation of the tightness of the crankcase of the internal combustion engine.
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How does a chainsaw carburetor work, on what principle does it work
Modern car engines are no longer equipped with a carburetor. Meanwhile, before, almost every driver knew how to adjust it. Today, chainsaws with injection engines have already begun to appear on sale, however, carburetor models will hold the palm for a long time, because their cost is 5-15 times lower than that of the modernized version.
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The carburetor consists of several main parts:
- aluminum body;
- diffuser and air damper at the inlet;
- nozzles (valves for adjusting the fuel supply);
- atomizer (it is he who provides injection);
- fuel (float) chamber.
The principle of operation of a chainsaw carburetor is quite simple. Fuel is supplied continuously, and its quantity is regulated by jets. Air enters through the air damper due to the air vacuum generated by the piston. The diffuser mixes fuel and air. It is this fuel-air mixture that enters the cylinder, forcing the engine to work.
How to adjust the carburetor on chainsaws
To understand how to properly adjust the carburetor on a chainsaw, you need to see it, and therefore we invite the reader to pay attention to the example below.
To make the adjustment, you only need a slotted screwdriver, however, it will not be possible to perfectly fine-tune the carburetor without a tachometer (of course, if the person is not a minder or a professional driver with experience). Now let’s try to understand how to set up the carburetor in a given situation.
Mechanic at home: adjusting the carburetor of a chainsaw with your own hands
Any internal combustion engine requires periodic maintenance, It doesn’t matter if it is the engine of a simple moped or a powerful multi-ton tractor. Such a tool as a chainsaw was no exception. After all, it is equipped with a single-cylinder two-stroke internal combustion engine, which also requires serious maintenance, although it is much easier to perform the necessary actions here. In today’s article we will talk about how to adjust the carburetor of a chainsaw with our own hands, find out how difficult it is, and figure out whether you need to be a professional mechanic to do this kind of work.
How to correctly and accurately adjust the carburetor: step by step instructions
In order to make the information easier to perceive, we propose to consider it on the basis of photo examples with a description of actions in tabular form. The basis is a chainsaw with initial settings.
You can learn more about the master class on adjusting the carburetor of a chainsaw in this video.
How to adjust the carburetor in a chainsaw
Chainsaw carburetor tuning is not a complicated process, so even a beginner can handle the adjustment. The setup procedure includes the following steps:
- Setting the motor at reduced speed for smooth operation.
- Adjusting the unit to supply fuel at maximum speed.
- Adjustment in XX mode.
- Checking the tool in each of the modes.
It is important to know! The process of adjusting the carburetor should be started after the tool has worked a little and warmed up.
In most saws, carburettors are equipped with three adjustment screws as described above. It is with the help of these screws that the functioning of the carburetor can be adjusted.
If the carburetor of the tool is not tuned, which makes it impossible to start the chainsaw, then the tuning work begins with screws “H” and “L”. Both the first and second screws turn clockwise 1/5 of a turn. After that, you can start the engine, letting it run for 3-5 minutes.
The next step is to regulate the low speed mode, for which you will need to use the screws “L” and “T”. The screw “L” must be tightened to the stop, having received high engine speed, and then loosened by 1/4. The idle speed is adjusted by tightening the screw “T”.
It is also important to adjust the thrust and maximum engine speed. This is done by gradually tightening the screw “H”, as well as observing the tachometer readings, which should correspond to the maximum value according to the instrument’s data sheet.
It is important to know! Exceeding the value of the maximum speed is unacceptable, as this will lead to seizure of the motor.
After completing the main work, it is important to check. To do this, the chainsaw must be allowed to cool, then start it up and check the operation at XX. If everything is normal, then the tool is checked in the operating mode as well. As you can see, adjusting the chainsaw with your own hands is not particularly difficult. Even if something goes wrong in the process, you can return the factory settings, as indicated in the instructions.
How to setup
Chainsaw carburetor adjustment is carried out as follows. Before adjusting the carburetor on a chainsaw, you should find out if all filters are clean. The device is adjusted with three screws:
- main jet H;
- idle L;
- idle speed adjustment S (some manufacturers call it LA or T).
Before starting the adjustment, you must read the instructions for the saw. When making the adjustment, you should follow the rules:
- The tool is installed on the workbench so that it is in a stable position.
- The chain of the device must be directed away from you.
- There must be at least 2 m between the instrument and other objects in the room.
It is important to have information on how the tuning takes place in the event of a malfunction of the structure. Turn on the carburetor and wait 10 minutes. Adjustment begins by finding the location of the screw L at which the idle speed will be high. Need a wrench to adjust the bolts. Gradually twist the bolt, first in one direction, then in the other, until the correct position is taken. Then twist the screw 1 / 8-1 / 4 turn counterclockwise. Then fix the idle with the S screw (or T, LA).
If, after tightening the needle bolt L, the chain does not move, then gradually turn the screw S clockwise until the chain begins to move. Then adjust S 1 / 8-1 / 4 turn back. If the chain moves, turn the screw S counterclockwise until it is tightened. Then we twist S by 1 / 8-1 / 4 turns in the same direction.
The internal combustion engine must function evenly. You should also check how it accelerates. If you press the accelerator, the revs should rise to the maximum. This means that the motor spins well.
At the end, the operation of the device is tested at idle. When the adjustment is done correctly, then the structure should not perform work like this:
- The chain is motionless.
- The sound of the internal combustion engine is the same as that of a 4-stroke generator.
- If you click on the accelerator, there will be a fast promotion.
If these requirements are not met, then the idle speed must be adjusted. To do this, tighten screw S as described earlier. If it does not help, you should repeat the adjustment from the beginning.
This is how manual configuration is done. Fine adjustment is carried out using a tachometer. All actions are the same, only the screws are turned based on the data of the tachometer. Thanks to this device, the carburetor can be adjusted faster.
Major malfunctions
If you have ever been interested in the carburetor design, you could not help but notice that all the holes on the assembly are extremely small. Even the smallest contamination caused by poor quality fuel can result in improper fuel or air circulation. Yes, filters are installed at the inlet and outlet, but they do not always cope with their task. What does this lead to? Any mechanic will tell you the consequences.
Adjustment process
The adjustment is carried out in 2 main stages:
- main (basic);
- accurate.
Chainsaw carburetor device
Most modern chainsaws are equipped with nearly the same carburetors. They practically do not differ from each other, and work on a similar principle. The only difference between cameras from different manufacturers is the material from which they are made. In expensive American, Swedish and German chainsaws, cameras are made of reliable alloys, on which protective coatings are applied. Cheap Chinese and Korean chainsaws are equipped with nodes made from cheap materials.
Each carburetor consists of the following elements:
- aluminum body with one-piece construction. Inside the body there is an inlet fitting, a main screw, an impulse channel, a bolt for adjusting the engine when idling;
- throttle valve. it is responsible for adjusting the amount of air required to enrich the fuel mixture;
- diffuser. located next to the chamber inlet;
- sprayer. designed to supply the fuel mixture directly to the carburetor chamber;
- float chamber. there is a float in it, which is triggered in the event of an insufficient amount of fuel;
- nozzles. are valves that are responsible for adjusting the amount of fuel.
This chain saw carburetor circuit is as simple and effective as possible. In some models of gardening tools, it can be supplemented with additional pipes, oil seals or filters.
The principle of operation of a chainsaw carburetor is quite simple. When the engine starts, the air damper located at the bottom of the housing opens. In this case, a vacuum is formed in the float and air chambers, caused by the movement of the piston. As a result, the standard diffuser is triggered, which begins to suck in air. The amount of intake air depends on the opening of the damper. When the piston is triggered, fuel begins to flow into the chamber through the inlet fitting. Its quantity and flow rate depend on the position of the nozzles.
Subsequently, the fuel in the air chamber begins to mix with air. After that, the finished air-fuel mixture passes through the intake valves, from where it is sent to the combustion chamber of the saw engine.
Why the chainsaw shoots the carburetor?
If, during the launch and operation of the instrument, its owner hears sounds resembling shots, then this indicates a malfunction of the unit in which the fuel is mixed. The reason for this, most likely, is the following malfunctions of the chainsaw carburetor:
- overtightened ignition. in this case, the fuel does not burn out, which leads to specific sharp shots;
- feeding a mixture with a low concentration of gasoline to the carburetor. to fix the problem, you will need to adjust the jets.
If the shooting sound comes from the muffler, the problem is that the fuel mixture is oversaturated with gasoline. If there is too little air in the fuel, then it will burn not only in the chamber, but also in the muffler. This will be evidenced by a large amount of carbon deposits on the inner walls of the muffler.
How to remove a carburetor from a chainsaw?
Before cleaning the carburetor or repairing it, this element of the chainsaw will need to be dismantled and disconnected from other components. To do this, you must follow a certain order of actions. The dismantling algorithm is as follows:
- First, remove the top cover by unscrewing 3 bolts around its perimeter;
- Remove the filter in the form of a foam pad;
- Disconnect the fuel supply hose;
- Remove the drive rod;
- Disconnect the cable end;
- Carefully remove and fully pull out the fuel hose.
Try to perform each of the actions as carefully as possible. Otherwise, there will be a risk of damage to important parts of the chainsaw.
Tuning Algorithm
The required quality of the fuel mixture depends on the quantity and quality of the fuel. The ratio of the supplied fuel and air is regulated by tightening special screws.
Attention! Before adjusting the saw, the engine must be warmed up. Performing work on a cold engine leads to distortion of the results and a decrease in the effectiveness of the tuned parameters.
There are three adjusting bolts on the body of the unit. Each of them is designated by Latin letters H, L, T.
Chainsaw carburetor adjusting bolts
- H. is responsible for ensuring high speeds of rotation of the shaft.
- L. designed to adjust low speeds.
- T. provides optimal tool idling.
Turning screws H and L clockwise decreases the supply of petrol (the fuel becomes leaner). When turned counterclockwise, the opposite situation occurs (the fuel is richer).
Depletion of the fuel mixture leads to an increase in the number of revolutions. Enrichment of the fuel mixture leads to a decrease in their amount.
Turning bolt T clockwise increases idle speed. Turning the knob counterclockwise decreases this speed.
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By turning the bolts, stop the movement of the saw chain at idle speed and eliminate extraneous noise when the power unit is turned on.