How To Adjust The Carburetor On A Chainsaw

How to adjust the carburetor on a chainsaw with your own hands?
How to adjust the carburetor on a chainsaw: what is a carburetor, in what cases adjustment is necessary, how it should be carried out.

When is adjustment necessary?

Most often, owners of a Husqvarn chainsaw and other manufacturers do not often have to adjust the carburetor. To understand that it is time to perform this operation, you need focus on the following signs:

  • After starting the engine, it stalls pretty quickly or it is impossible to start it at all. This is most often associated with the use of a lean fuel mixture;
  • During the operation of the tool, fuel is consumed in an increased amount. There may also be an increased generation of exhaust gases. As a rule, this happens in the case of using a supersaturated mixture.

It should be noted that adjustment failure is quite rare, but it can occur in the following situations:

  • In case of failure of the fastening of the adjusting screws. This could be due to vibration or breakage of the protective cap. In principle, the likelihood of this is rather low if no one has touched them.
  • Serious wear of the engine, primarily the piston engine. In this case, the factory settings will be of little use. A temporary solution in such a situation is to adjust the carburetor of the chainsaw. However, you shouldn’t expect this to permanently fix the problem. After performing this operation, you need to be prepared for the fact that soon you will need to repair the engine.
  • Also, the need for adjustment may be associated with the appearance of a blockage in the carburetor. This can be caused by the use of not the best quality gasoline, broken air filter, or scale formation. In such cases, adjustment alone is not enough. It is necessary to disassemble the carburetor and remove it from dirt.

Chainsaw carburetor device

Even before you start adjusting the carburetor, it will be useful to familiarize yourself with the device and how this tool works. Subsequently, this information will help prevent many problems.

The design of the carburetor can be distinguished a number of required elements, however, some modifications of this tool may contain additional ones. Therefore, you need to look at the chainsaw model. These elements are:

  • A tube. The main element, made like a wind tunnel, which provides air intake. There is an air damper across it, which changes its position and thereby contributes to an increase in the force of the incoming air or its decrease.
  • Diffuser. So it is customary to call the narrowing of the tube, the main purpose of which is to increase the speed of the air flow in the area where the hole for the fuel supply is located;
  • Spray. It is this device that ensures the flow of fuel into the air channel. It is fed directly into the atomizer by means of a nozzle from the float chamber.
  • The float chamber acts as a kind of reservoir, which is necessary to maintain a constant fuel level at the entrance to the air channel.

The very same carburetor works as follows: The air duct provides a fast flow of air that can vary in speed depending on the position of the damper. The level of the float allows you to adjust the degree of opening of the fuel supply channel, and it itself depends on the position of the above-mentioned air damper. When air enters the diffuser, it begins to lift the incoming fuel along with it and atomize it. At this stage, a mixture is formed, which goes into the cylinder, bypassing the intake manifold.

Typically, the pressure level in the float chamber does not differ from atmospheric. In the air channel, a different picture is observed, since a rarefied pressure is maintained there. It is the difference in fuel pressure that ensures its flow through suction through the nozzle, from where it goes into the air channel. It is very important that with an increase in the degree of opening of the air damper the amount of air also increases, which, accordingly, allows more fuel to be supplied. In turn, it is the amount of fuel that affects the speed at which the engine will operate.

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Regulation rules

Regardless of the manufacturer’s tool to deal with, carburetor adjustment requires fulfillment of some requirements:

  • To properly adjust the carburetor, you must first warm up the engine. To do this, turn it on for 10 minutes;
  • Check the air filter, which must be in working order. Its readiness is judged by the absence of contamination;
  • When rotating the chain with the adjusting screw T, stop it completely. This is done by turning the screw counterclockwise.

In the process of adjusting the carburetor, there is a risk of harm to your health. Therefore, in order to minimize such unpleasant consequences, you need to make sure that the chain is directed in the opposite direction. In turn, the saw must be positioned on a level surface and make sure that it does not come into contact with the cutting edge of any objects.

The process of fine adjustment of the screws requires adherence to a certain order: L. H. T. Screw L is used to select the maximum engine speed. This is done by turning the screw clockwise or in the opposite direction until the maximum is reached.

Considering that everything is done by “feeling”, a tachometer or a clear ear for music will not interfere. It is very important that you have a clear idea of ​​what sound the engine speed limit is. Then you can stop in time. First of all, you need to be careful with the H regulator, because otherwise it may result in engine failure. And to repair it, you will have to spend a lot of money. For this reason, it is desirable that such work be performed by a qualified technician.

Adjustment tools

To tune the carburetor, you will need a Phillips or slotted screwdriver of different lengths or thicknesses; the size depends on the design of this unit and the features of the engine assembly. It should be noted that some manufacturers make carburetors designed to use special tools.

In particular, special types of screwdrivers may be required to tune Husqvarna carburettors and other imported tools. It is advisable to clarify this question even when buying a chainsaw, so that you can purchase the necessary additional equipment in advance.

In addition, you will need refined gasoline or acetone to flush and clean the device. They are used to clean the outer surfaces of the carburetor. All internal channels are flushed with kerosene, diesel fuel or white spirit. Before flushing, the carburetor is disassembled, all rubber or plastic parts that may suffer from contact with aggressive chemical compounds are removed.

Open-end or spanner wrenches are used to disassemble the carburetor. Internal canals are flushed in specially designated trays, sometimes plastic syringes are used for this.

How to properly adjust the carburetor with your own hands?

After rinsing and completely cleaning the carburetor, assemble it and start adjusting. First of all, you should understand the purpose of the adjusting screws. The instruction will help with this, but some general points should be considered right away. The most common designations for screws are:

  • H. Adjusts the state of the main jet, i.E. Adjusts the maximum speed of rotation of the motor shaft;
  • L. Adjusts the idle jets (responsible for the minimum shaft rotation speed);
  • T. Regulates the engine idling. It can also be designated by the letters LA or S, on some models of carburetors it is not at all.

Turning screws H and L clockwise depletes the air-fuel mixture, and counterclockwise enriches it (the amount of gasoline increases). When the screw T rotates, the idling speed of the shaft changes. It increases clockwise, and decreases in the opposite direction.

Figure 2. Carburetor adjustment mechanisms

Before proceeding with direct actions, you should find and carefully study the information on the position of the adjusting screws (the value of the angles of rotation during adjustment). This information is available in the instructions for the chainsaw. Then you need to prepare the workplace. Lay the saw on a flat horizontal plane, directing the chain in the opposite direction from you. Detach all covers, remove foam rubber and air filter. At this, the preparatory operations are considered completed, you can proceed to the main part of the work.

Carburetor adjustment procedure:

  1. Tighten the screws H and L clockwise with a smooth motion clockwise. Be careful not to break the screws. This will cause the complete loss of the carburetor.
  2. Unscrew both screws one and a half turns.
  3. Run the engine for 10 minutes and warm it up. This is a necessary moment, since it will not be possible to correctly adjust the carburetor on a cold engine.
  4. Turning screws H and L, alternately adjust the shaft rotation at maximum and minimum speed.
  5. By adjusting the position of the screw T (or it may have another designation), the idle speed of the chainsaw is adjusted. It is necessary to achieve smooth and stable engine operation. It is important to monitor whether the chain is idling or not. If it moves, turn the screw a little more counterclockwise.
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You can check the operation of the engine visually and by ear. Too rich mixture will cause thick smoke from the exhaust. When the lean mixture is being fed, a whistling sound is heard while the saw is running. Excessive economy mode is harmful. If the L screw is adjusted to “lean” fuel, there will be problems with starting the engine. If the H screw is set to lean, the saw will noticeably lose power. You can determine the correct setting by the following criteria:

  • At idle speed, the engine does not stall, and the chain is stationary;
  • There is no excessive smoke from the exhaust pipe while the engine is running;
  • The engine demonstrates good throttle response (picks up speed quickly when you press the accelerator).

A detailed description of the setting is available in the instructions that come with the instrument in the delivery set. It should be carefully studied, as there may be some features or specific requirements established by the manufacturer and related only to this saw model. If all requirements are met exactly, the performance of the chainsaw will be restored to its original state.

When is carburetor adjustment necessary?

Initially, from the moment the tool was sold, all carburettors were adjusted and tuned at the factory. However, in the process of operation, the settings gradually get lost, and the operating mode changes in accordance with the operating conditions. Signs of a carburetor malfunction may include:

  • Too high gasoline consumption, thick smoke comes from the exhaust pipe;
  • Engine power is clearly not enough to perform normal tasks;
  • Engine speed “float”;
  • After starting, the motor stalls either immediately or after a few seconds;
  • The engine cannot be started at all;
  • The chainsaw “shoots”, there are sharp claps in the tool engine.

It should be noted that during the running-in of a new engine, the carburetor is set to a reduced fuel supply in order to limit the engine power. After the end of the run-in, the fuel supply increases to the nominal value. These adjustments are made using the adjusting screws on the carburetor body (there are usually two or three).

Chainsaw carburetor adjustment: we analyze all the technical nuances of the work

how to adjust the carburetor on a chainsaw

Summer cottage construction and repairs are not complete without the use of a chainsaw, as well as garden maintenance. Due to a malfunction of the tool, all work can get up, so it is so important to be able to disassemble it yourself, find problems and fix them. With sufficient experience and dexterity, it is even possible to adjust the carburetor of a chainsaw. A complicated procedure, or rather, jewelry. How to carry out the adjustment procedures, we suggest you disassemble today.

Chainsaw carburetor device

Not a single repair event is complete without knowledge of the basics of the mechanism. By understanding the constituent elements and the principle of operation, it is easier to determine the cause of the breakdown.

Any malfunction in the carburetor threatens to stop the engine

The carburetor is one of the main functional parts of the engine, which serves to prepare and supply a fuel mixture consisting of certain proportions of fuel and air. As soon as the proportions are violated, the engine starts to “junk”, or even stops working altogether.

You can achieve the correct operation of the carburetor by examining its “filling”:

  • Cross-flap tube for air flow regulation.
  • Diffuser. Constriction to increase the air flow rate, located near the fuel inlet.
  • The nozzle from which fuel comes (fuel needle in the diagram).
  • A float chamber that regulates the fuel level at the entrance to the channel.

This is how it looks in the diagram:

The diagram shows the interaction of fuel and air flow

How it works: A jet of air in the diffuser atomizes the fuel, creating a mixture that enters the cylinder. The more fuel is supplied, the higher the engine speed. Different carburettors work in the same way.

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When is adjustment necessary at all?

Specifically, adjusting the carburetor of a chainsaw is required in rare cases, more often there are problems associated with the flow of fuel or wear of parts. But sometimes “symptoms” indicate that it is necessary to adjust the mechanism. Here are some signs:

  • After the engine starts, it immediately stalls. Alternatively, it won’t start at all. The reason lies in the excess air and fuel shortage.
  • Increased fuel consumption and, as a result, a large amount of exhaust gases. This is due to the reverse process. Oversaturation of the mixture with fuel.

The reasons for the adjustment failure can be mechanical:

  • Strong vibration damages the protective cap, causing all three bolts to lose their position.
  • Due to wear on the piston part of the engine. In this case, adjusting the carburetor of the chainsaw will only help out for a while, it is better to replace the worn part.
  • Due to clogging caused by low-quality fuel, scale or damage to the filter. The carburetor requires complete disassembly, flushing and adjustment.

If the chainsaw suddenly stops working, you need to disassemble it to find out the reasons

Step by step instructions for disassembly

The carburetor device of models of different brands is almost the same, so take the Partner chainsaw as an example. We carefully remove each element and put it in order to make it easier to assemble later.

Chainsaw carburetors from different manufacturers, if they differ, it does not matter

The top cover is removed by unscrewing three screws. Following it is foam rubber, an integral part of the air filter.

The arrows indicate the bolts that must be unscrewed to remove the cover

Then we remove the fuel hose, followed by the drive rod.

The upper arrow points to the fuel hose, the lower arrow to the drive rod

Next, remove the tip of the cable.

The arrow shows the end of the cable to be removed.

On the left from the fitting, we pull together the gasoline hose.

We also carefully remove the gasoline hose indicated by the arrow

We finally disconnect the carburetor, it is ready for adjustment. Its mechanism is rather complicated, therefore, if further disassembly of the carburetor is required, the elements should be removed very carefully. They are small, so they can be lost.

The carburetor consists of many small parts, which should be laid out in order during disassembly.

Chainsaw carburetor adjustment: we analyze all the technical nuances of the work

Summer cottage construction and repairs are not complete without the use of a chainsaw, as well as garden maintenance. Due to a malfunction of the tool, all work can get up, so it is so important to be able to disassemble it yourself, find problems and fix them. With sufficient experience and dexterity, it is even possible to adjust the carburetor of a chainsaw. A complicated procedure, or rather, jewelry. How to carry out the adjustment procedures, we suggest you disassemble today.

When is adjustment necessary at all?

Specifically, adjusting the carburetor of a chainsaw is required in rare cases, more often there are problems associated with the flow of fuel or wear of parts. But sometimes “symptoms” indicate that it is necessary to adjust the mechanism. Here are some signs:

  • After the engine starts, it immediately stalls. Alternatively, it won’t start at all. The reason lies in the excess air and fuel shortage.
  • Increased fuel consumption and, as a result, a large amount of exhaust gases. This is due to the reverse process. Oversaturation of the mixture with fuel.

The reasons for the adjustment failure can be mechanical:

  • Strong vibration damages the protective cap, causing all three bolts to lose their position.
  • Due to wear on the piston part of the engine. In this case, adjusting the carburetor of the chainsaw will only help out for a while, it is better to replace the worn part.
  • Due to clogging caused by low-quality fuel, scale or damage to the filter. The carburetor requires complete disassembly, flushing and adjustment.

If the chainsaw suddenly stops working, you need to disassemble it to find out the reasons