The operation of a chainsaw engine is based on the combustion of a special mixture, which consists of fuel, oil and air. To prepare such a mixture and evenly transfer it to the combustion chamber, the engine has a special device - a carburetor.

The design of the saw includes a device that has factory settings. As the device is used, these settings become lost, and the carburetor must be adjusted again. To understand how to adjust a chainsaw carburetor, you need to know what parts the device consists of and how it works.

The design and principle of operation of the carburetor

Let's find out the structure of the chainsaw carburetor. This device consists of:

• housings;
• diffuser, which is located at the entrance to the device;
• jets;
• valves regulating the supply of the mixture;
• special sprayer;
• float chamber.

The device has 2 or 3 adjusting screws equipped with springs. At the end of the screws there are needle-cones.

The principle of operation of a chainsaw carburetor:

1. When the engine is turned on, the air damper opens.
2. The air moves forward and mixes with the fuel in the diffuser, where the passage narrows.
3. The air flows through the jets, then is cleaned by a filter and enters through a damper located at the diffuser inlet.
4. In this case, a special damper, which is located behind the diffuser, distributes the mixture, and it enters the combustion chamber.

The device is designed in such a way that the volume of fuel that passes through the jets is regulated by the chainsaw bolts. The volume of fuel in the chamber depends on the valve with a sharp cone. The operation of this valve is regulated by a membrane that controls the flow of mixture into the chamber. The operation of these components depends on the rotation of the internal combustion engine. The mixture is purified using a filter.

When adjustment is needed

The carburetor must be adjusted:

1. If the settings are lost due to loose screws or vibration, or when trying to adjust the device.
2. If the housing cover is broken.
3. To find out the reasons why the design does not work.
4. When the engine does not turn on or runs with effort, and then immediately dies out.
5. When a chainsaw shoots into the carburetor or “sneezes.”
6. The chainsaw vibrates a lot.
7. To check why there was excessive fuel consumption.
8. When thick exhaust appears.
9. If the device does not receive gasoline.
10. When the spark plugs are blackened or coated.
11. The saw cannot operate at high speeds and increase power.
12. Check the engine if it turns off when revving up.
13. The operation of the air purification units was disrupted.
14. Debris has entered the mixture distribution system.
15. The pistons have worn out.

Adjustments also need to be made when changing the brand of fuel and changes in humidity.

How to setup

Setting up a chainsaw carburetor is done as follows. Before adjusting the carburetor on a chainsaw, you should find out whether all filters are clean. The device is adjusted with three bolts:

• main jet H;
• idling L;
• idle adjustment S (some manufacturers call it LA or T).

1. The tool is installed on the workbench so that it is in a stable position.
2. The device circuit must be directed away from you.
3. There must be at least 2 m between the instrument and other objects in the room.

It is important to know how adjustments occur when the structure malfunctions. Turn on the carburetor and wait 10 minutes. The adjustment begins by finding the location of the screw L at which idle speed will be high. You need a wrench to adjust the bolts. Gradually turn the bolt, first in one direction, then in the other, until the correct position is reached. Then turn the screw 1/8-1/4 turn counterclockwise. Then the idle speed is corrected with screw S (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 by 1/8-1/4 turn back. If the chain moves, turn screw S counterclockwise until it tightens. Next we twist S by 1/8-1/4 turn in the same direction.

The internal combustion engine must function smoothly. You should also check how it accelerates. If you press the accelerator, the speed should increase to maximum. This means that the engine spins well.

At the end, the operation of the device is tested for Idling. When the adjustment is made correctly, the design should not work like this:

1. The chain is motionless.
2. The sound of an internal combustion engine is the same as that of a 4-stroke generator.
3. If you press the accelerator, a rapid spin will occur.

If these requirements are not met, then the idle speed must be adjusted. To do this, tighten screw S as described earlier. If this does not help, you should repeat the adjustment from the beginning.

This is how manual tuning is done. Fine adjustment is carried out using a tachometer device. All actions are the same, only the screws are turned based on tachometer data. Thanks to this device, the carburetor can be adjusted faster.

Malfunctions and their elimination

Repairing a chainsaw carburetor with your own hands allows you to eliminate all problems that arise during the operation of the device.

If the internal combustion engine spins intermittently and accelerates for a long time, then you need to tighten L counterclockwise by 1/8 of a turn. Then adjust bolt S again. These adjustments should be made until the motor functions correctly and accelerates quickly.

Then check the setting of screw H. Accelerate the motor to maximum. Watch the exhaust and how the engine spins. If blue smoke comes out of it and the saw makes a loud noise, then this means that the carburetor is creating a mixture that is too rich. Highest engine speed less than normal. Soot forms in it. In case of such a problem, you need to turn H a little clockwise. Next, control the operation of the motor and, if necessary, repeat the setting.

If the saw squeals, this means that the engine is overheating, the exhaust is crackling, and there are misfires. This means that the mixture is unsaturated, and the highest engine speeds are higher than normal. This leads to overheating of the engine, combustion of the piston, cylinder and burnout of the spark plug. If this problem occurs, adjustment should be made by turning H 1/4 turn counterclockwise.

If fuel does not flow into the combustion chamber, this problem is caused by a clogged fuel filter, nozzles or device channels. To eliminate the malfunction, you will need to completely disassemble the filter and blow through these channels using a compressor. Carburetor fluid is used to clean the channels.

It happens that there is an overflow of fuel in the carburetor. This happens if the membrane has failed, dried out and become rough, and began to put pressure on the rocker arm attached to the needle. Then the needle is adjusted. To change the membrane, you need to remove the carburetor.

The motor runs intermittently and does not pick up speed well. This happens when the filter is clogged. It is necessary to remove the cover of the device and clean it using detergents.

How to remove a carburetor

Before repairing or cleaning the carburetor, it must be dismantled and disconnected from other systems. Dismantling the carburetor is carried out as follows:

1. Filming top cover. To do this, you need to unscrew the bolts (3 pieces) that are located around the perimeter of the cover.
2. Remove the carburetor filter.
3. Then disconnect the gasoline supply hose.
4. Disconnect the motor drive traction.
5. Unscrew the cable connection end.
6. Carefully remove and pull out the gasoline supply hose.

DIY disassembly

Disassembling the Homelite chainsaw carburetor is carried out as follows. Prepare the place - flat surface. You will need the following tools:

• set of screwdrivers and wrenches;
• detergent composition;
• ultrasonic bath for cavitation;
• a large piece of cardboard.

After you have removed the carburetor, you should disassemble it. Disassembly of the carburetor is carried out in the order provided for by the design of the device.

The parts of the device are small, so they should be folded in order, making sure that no components are lost.

After disassembly, the device is troubleshooted and non-working parts and components are replaced. Wash the device with a special liquid, dry it, and wipe with a dry cloth. Blown through compressed air tubes and jets. Before this, they are treated with ultrasound to remove plaque.

How to clean

When doing the work yourself, you need to know approximately how to clean and flush the carburetor. Wash the device as follows:

1. Unscrew the screws on the device body.
2. Open the lid and take it out small parts and lay them out on fabric.
3. The walls of the device and all parts are treated with air from the compressor.
4. If carbon deposits remain on the components, they are wiped with a degreaser.
5. The components and body are dried.
6. Assemble all the components of the carburetor and install it on the chainsaw.

It is necessary to flush the carburetor if low-quality gasoline was used to refuel it or if a chainsaw was used severe frost. After cleaning, the engine will work better and the chainsaw will spin up faster.

Adjusting the chainsaw carburetor ensures effective work tool at full power with economical fuel consumption. The adjustment must be made with a clean fuel and air filter. For a larger number of carburetors, adjustment is carried out with three screws: for maximum and minimum speed and idle speed adjustment.

Screws H and L adjust the ratio of the mixture of gasoline and air, determined by the opening of the carburetor throttle valve. When the screws are unscrewed, the mixture becomes richer, and the speed drops accordingly; when the screws are tightened, the mixture becomes leaner - the speed increases.

The designation H refers to the maximum speed screw that controls the main jet, L - to the minimum speed screw that controls the idle jet. Using screw S, the idle speed is precisely adjusted. Sometimes, to simplify setup, the number of available carburetor adjustment screws is reduced.

Setting up a chainsaw carburetor is divided into two stages - basic (factory settings), carried out with the engine turned off, and final, carried out with the engine running and warm. The exact value of the rotation angles should be taken from the operating instructions for the specific chainsaw. Failure to follow manufacturer's instructions may result in engine damage.

Basic carburetor adjustment.

The adjusting screws for maximum H and minimum L revolutions are slowly turned clockwise until they stop, and then turned back 2 turns; other settings are also possible

Checking and adjusting idle speed.

We find the highest idle speed, to do this we slowly turn screw L in different directions. After finding the position of the highest engine speed, turn screw L 1/4 turn counterclockwise. If the chain rotates at idle, screw T or (S) should be turned counterclockwise until it stops.

Checking and adjusting the maximum speed.

Changing the maximum number of revolutions is carried out by screw H. When it is turned in (clockwise rotation), the revolutions increase, and when turned out, they decrease. Chainsaw engines have the highest rotation speed from 11,500 rpm. up to 15000 rpm. A higher speed is not ensured by the ignition, in addition, it becomes dangerous for the engine. Limit speeds can be determined by interruptions in ignition. If they do, screw H is turned slightly counterclockwise.

If the engine operation is not checked for acceleration and maximum speed, then the adjustment of the chainsaw cannot be considered complete.

Acceleration check.

When you smoothly press the gas trigger, the engine should confidently and quickly pick up speed from idle to maximum (from 2800 rev. to 11500-15000 rev., depending on the unit). If the speed is gained slowly, with a delay, screw L must be slowly turned counterclockwise, but no more than 1/8 of a turn.

After adjusting the acceleration and maximum speed, you should check the operation of the saw again at idle speed - the engine should run stably, the chain should not move. The chainsaw adjustment must be repeated if this condition is not met, except for the basic adjustment stage.

When set correctly, the chainsaw runs smoothly and should not emit excessive smoke as the engine speed increases. When the carburetor adjustment was initially set incorrectly, you will immediately notice clouds of smoke that may be released during operation. An incorrectly adjusted carburetor can shorten the life of the chainsaw. Learn how to adjust your Chinese chainsaw to ensure it runs smoothly and efficiently.

Setting up a Chinese chainsaw

The procedure can be challenging. Some models are made after the example of expensive and high-quality models produced by famous brands. For this reason, you can see it on some Chinese analogues.

1. Idle Speed ​​Screw - This adjusts the engine speed at idle. If it is set too low, the saw will not work. If you install high, you may run into problems with the chain. Is it dangerous!
2. The low speed adjustment screw is a low speed setting. This is an adjustment that controls the air/fuel mixture at idle. In the first case not correct adjustment the saw will not start at idle speed. In the second case, engine failure will occur.
3. High speed adjustment screw. This is a regulation that controls the air-fuel mixture at high speeds. Incorrect setting leads to high speed of the chainsaw.

Regulation rules

Step 1. Check the fuel level in the fuel tank. This tank should be half full. If there is less fuel, it will make proper carburetor adjustment more difficult.

Step 2. Gain access to the carburetor. The location may vary depending on the model and manufacturer of your specific chainsaw. Typically, you will need an adjustable wrench and a hex wrench to remove the bolts from the chainsaw body. Remove the housing. Carburetor adjustment will be made using small screws near the engine.

Step 3. Start the chainsaw and wait three minutes. This allows the engine to warm up, which is necessary for proper carburetor adjustment.

Step 4. Turn the idle speed adjustment screw. You will hear the engine spinning or slowing down as you turn the propeller. Set the engine to idle so it runs at high speed. This will help prevent the engine from switching off unintentionally.

Step 5. Turn the screw adjustment to low speed. Turn it to one side until the engine runs as strong as possible. Turn the screw the other way. Note the two positions of the auger and turn the screw so that it is halfway between these two points. Pull the chain saw a little to check how it operates at low speed.

Step 6. Pull the trigger to bring the chainsaw to full throttle. If the engine runs normally, the full speed adjustment screw is installed correctly. If the engine is acting up, adjust the screw and pull the trigger again. Repeat until the chainsaw is running at full speed without interruption.

Step 7 Reattach the chainsaw body.

The carburetor setting of a Chinese chainsaw affects the operation of the tool. If you notice a difference in your chainsaw's performance, or if it's starting to run rough, a tune-up can help. While newer units are designed to prevent adjustment by anyone other than a licensed professional, older models feature easy-to-use screws for quick adjustments.

Adjusting the high speed adjusting screw not only affects the power output, but also the high rotation speed. If the screw is turned too far clockwise, the permissible operating frequency will be exceeded. This can lead to engine damage caused by lack of lubrication and overheating, among others. Adjustments to the high speed adjuster screw setting can only be made if an accurate tachometer is available to check the maximum engine speed of 13,000 rpm (with the bar and the chain properly tensioned).

When an engine is factory checked, the carburetor is set to produce a rich mixture to ensure that the cylinder bore and bearings receive additional lubrication during the period of operation. The high speed adjustment screw may be turned no more than 1/4 turn clockwise.

Do you own a Husqvarna 137 branded chainsaw? Then check out a similar article about.

Warning! The maximum permissible engine speed must not be exceeded! Please note that even minor changes to the adjusting screws have a noticeable effect on engine behavior.

Video: adjusting a Chinese chainsaw

Often the difference lies in the quality of the parts and the presence or absence of a primer connection tube - hand pump pre-pumping.

Therefore, we will consider them almost impersonally, without going into the nuances.

The design and principle of operation of a chainsaw carburetor

The task of the carburetor is to prepare a mixture of gasoline and oxygen and dose it into the cylinder. Mixing occurs in the diffuser (16) - the tapering part of the carburetor where acceleration occurs air flow. Gasoline of different fractions (larger and finer) and purified air after the air filter enter the diffuser through 2 jets (15) and (12). Its quantity is regulated by the air damper (7) at the diffuser inlet. Quantity ready mixture, supplied to the cylinder, is regulated by another damper (8) located behind it.

Two screws (17) and (10) (L and H) regulate the amount of gasoline passing through the jets. The amount of gasoline in the float chamber (14) is regulated by a needle valve (11), the operation of which is monitored by a membrane (13). The second membrane (4) doses the amount of fuel supplied to the chamber depending on the engine speed. Along the way it is filtered through a filter (6).

If both filters: air and gasoline are clean, the channels and jets are not clogged, the membranes are intact, and the needle valve reliably regulates the amount of gasoline in the float chamber, then the carburetor is in good condition, and for normal training mixture, you need to correctly adjust the amount of gasoline supplied through the jets. We will not talk about mechanical wear of the metal parts of the body and carburetor damper rods, because it will be cheaper to simply replace it than to repair it.

How to adjust the carburetor on a chainsaw?

All saws come from the factory with an adjusted carburetor.

And, since it is protected by a plastic case, it does not require additional adjustments for a long time. And you should interfere with its operation only when the saw, with a guaranteed working cylinder-piston group, begins to stall, which is most often caused by a lack of fuel and, as a consequence, an excess of air.

The second symptom bad work carburetor is excessive fuel consumption and increased smoky exhaust, indicating an excess of gasoline in the mixture. In this case, before going to the carburetor, you should clean (or replace) air filter and make sure that the cause has not been eliminated.

Sometimes a carburetor adjustment disorder occurs gradually due to increased vibration tool, as a result of which the adjusting screws may turn from their original positions.

First of all, even before removing and disassembling the carburetor, you should try to adjust it. For this:

1. Start adjusting the carburetor with screw L, which adjusts the fuel supply at low speeds. Rotate it to achieve the highest speed. The speed increases when this screw is tightened.

2. Next, use screw H to adjust the quality of the mixture. If the saw smokes, this is a sign of a rich mixture, and if it squeals, this is a sign of a poor mixture. In the first case, screw H should be tightened, and in the second - vice versa. You should be very careful with this screw; incorrect adjustment can even damage the saw. Under no circumstances should it be tightened too much.

3. The adjustment is completed by setting the idle speed, which is set with screw T. At high speeds, the clutch cams are in the open state and the saw chain moves. Screw T adjusts the choke adjuster stop from the outside and does not go inside the carburetor. You should not keep the engine speed too low, as this increases the load on the crank mechanism, but the chain must also be guaranteed to stop at idle. This screw may have a different letter meaning in some saws.

Some carburetors initially have only one setting - idle; in them, the quality of the mixture is predetermined by the parameters of the jets and the factory settings initially. The idle speed adjustment video on such carburetors is also suitable for all other types of similar devices:

And a violation of the operating modes of the saw without screws for adjusting the speed and quality of the mixture may indicate that it needs to be repaired or at least cleaned.

It remains to add that the final adjustment should be made only on a heated saw that has worked for at least 10 minutes.

Do-it-yourself carburetor disassembly and repair

Let’s make a reservation right away: if you are not an expert in this type of activity, then it is better to contact service center. Sometimes the cost of a carburetor can reach a third of the cost of the entire saw.

But, if you decide to disassemble the carburetor yourself, we recommend finding a pair of free hands, putting a video recording device in them and in detail close-up Make a video of carburetor disassembly. This will definitely help when assembling it, because mark small parts for correct order its implementation is almost impossible.

In almost 80% of cases of carburetor failure, the jet that supplies fuel to the diffuser can be blamed. But, before cleaning it, we recommend stocking up on a repair kit, which necessarily includes membranes, gaskets, and sometimes this jet with a needle valve.

Even if disassembly reveals their integrity, it would be better to install new ones, because even a micron change in the parameters of the membranes can affect the operation of the device.

If the jet has to be cleaned, it is better to do this by first unscrewing it using a thin calibrated wire. It is better to blow out the second jet with your mouth using an attachment tube or with a bicycle pump, but in no case with a compressor - there is a high probability of damage.

We have selected a video about repairing the carburetor of a Shtil 180 saw, which has only an idle screw. But its internal structure is the same as almost all chainsaw carburetors:

And the point here is not only that the missing adjusting screws clutter the picture, distracting from the essence of the process, but that this disassembled carburetor can also be slightly adjusted by adjusting the quality of the mixture. If your Stihl suffered from increased fuel consumption and smoked before repairing the carburetor, then you can reduce the fuel supply by increasing the clearance of the needle valve by slightly bending its rocker arm. Using the reverse procedure, you can increase the fuel supply.

Always clean the filter when disassembling. To remove deposits, you can use WD-40, but if you remember that it is actually white spirit with the addition of oil, then you can get by with it. It is also possible to use kerosene or acetone.

The simplest, or preliminary, adjustment of the chainsaw carburetor can be done as shown in the video, and the final adjustment can be made after the saw has warmed up:

Dear readers, if you have any questions, please ask them using the form below. We will be glad to communicate with you;)

Carburetor in engines internal combustion is responsible for preparing the fuel mixture. It consists of gasoline, air, and oil. When all these ingredients were used in incorrect proportions, the engine will not be able to operate normally. To prevent this, adjusting the chainsaw carburetor is necessary.

The principle of operation of the carburetor

Regardless of the manufacturer of the chainsaw, the order and principles of operation of the carburetor remain unchanged. This device consists of several main elements:

• Tapered air supply tube.
• Fuel supply system.
• Adjustable air damper.

Under atmospheric pressure After pre-cleaning, the air enters the narrow part of the tube, where its flow is regulated by a damper. Also here the air becomes rarefied and the resulting vacuum is drawn from the fuel line. flammable liquid. To adjust the fuel flow, a special needle is used, connected to the nozzle chamber. The quality of the fuel mixture is regulated using a damper - when the air is opened, more fuel begins to flow into the carburetor and the power of the power plant increases.

To avoid problems with the operation of the tool, it is necessary to periodically adjust the chainsaw. When too much air enters the mixture, it becomes lean and engine power is reduced. Air deficiency also negatively affects the operation of the unit, as fuel consumption increases. At the same time, it does not burn completely, which leads to the appearance of carbon deposits on the cylinder walls. It is quite obvious that the question of how to adjust the carburetor on a chainsaw is asked by many owners of this tool.

However, first it is worth noting the signs of quality operation of the power plant:

• The momentum is picking up quickly.
• The sound when the engine is running is similar to a four-stroke.
• At idle speed the chain does not spin.

Situations in which tuning is necessary

The new tool is already ready for use. In this regard, for some time the question of how to adjust the carburetor on a chainsaw will not arise. However, experienced unit owners often fine-tune the unit. To do this, you do not need to disassemble the carburetor at all, since its design provides three adjustment screws:

• L - used at low speeds.
• N - allows you to set the maximum supply of flammable liquid.
• T - necessary for idle adjustment.

All fine-tuning actions are carried out by ear, and at this time you must adhere to safety rules. Before starting any manipulations, the adjustment screws should be marked to make it easier to return to the default setting if necessary.

Most often, problems are caused by adjustments that are carried out after failures in the operation of the unit. Among the main reasons for their appearance, it should be noted:

• Unbalance of screws and violation of the location of the protective cap.
• Wear of the piston system, which requires changes to the composition of the fuel mixture.
• Problems with the operation of the carburetor itself.

Adjustment algorithm

All work on setting up a carburetor chainsaw is carried out in four stages:

And now in as much detail as possible about how to adjust a chainsaw. If the tool does not start, then it is necessary to set the adjusting screws H and L to their original position. Then you have to start the engine and let it warm up. After this, you can begin adjusting at low speeds. To achieve optimal operating mode, screws L and T must be used.

First of all, use screw L to start the engine at maximum speed, and then release it by ¼. Screw T will allow you to adjust the operation of the power plant at idle. Adjustment traction and maximum speed This is done using screw H, which must be tightened slowly while monitoring the readings of the electronic tachometer. It is important to remember that you must not exceed maximum amount revolutions declared by the tool manufacturer.

After making adjustments, allow the engine to cool. Then it remains to start it in accordance with the algorithm for starting a cold unit. If there are no problems at this time, and the chainsaw works well at idle, you should check it under load. If a lack of power from the power plant is detected, adjustment is made using screw H.

Almost everything Chinese chainsaws are equipped with carburetors, the design of which is similar to European models. Therefore, the differences in setting will be insignificant - during the initial setting, screws H and L must be d Turn it out two turns. All subsequent actions remain unchanged.