Adjusting the carburetor of a Husqvarna 142 chain saw

Signs of incorrect carburetor operation

Improper carburetor operation can be caused by clogged inlets and improper adjustment.

Signs of incorrect operation:

Do you always need an adjustment

Before tampering with the factory settings of the carburetor, make sure that the chain saw’s malfunction is related to it:

If there is nothing wrong with the quality of the fuel, the chainsaw engine may not start, from clogged fuel and air filters:

adjusting, carburetor, husqvarna, chain

To diagnose the fuel filter, disconnect the gasoline channel from the carburetor and pump the fuel. If there is little or no pressure in the pipe disconnect the filter.

Before doing so, empty the tank from the mixture and remove the filter element itself. A clogged replacement cartridge can be cleaned, but it is best to replace it with a new one. Clean regularly when working with the tool in dusty conditions.

Be careful when removing the air cleaner so that airborne dust that has accumulated during operation does not get into the carburetor: it could be expensive to repair.

After disconnecting the cartridge, carefully clean off any accumulated dirt and flush it thoroughly with detergent. Then dry it out and put it back in place carefully.

Instructions for setting and adjusting with your own hands

Before setting up the Husqvarna 137 chain saw, it must be installed. Before you start it is necessary to study the construction of the chain saw Husqvarna 137.

  • Be sure to wear gloves for protection. They are not included in the delivery, so you should take care of buying them in advance. First you need to install the comb of the saw and fasten it with two screws.
  • If there are no chains and guide bars installed, they must also be put in place. To do this, remove the cover and the nuts securing it. If there is a shipping gasket on the chain, it must be removed.
  • Adjust the chain tension with the adjusting screw. It is important that the catch can fit into the hole in the bar. To advance the grip you need to turn the adjusting screw against the clock hand. That’s the way to get the grip in the correct position.
  • Next you need to prepare the chain for installation. To do this, select its correct position. The sprocket is placed on the chain, which is located behind the clutch drum. The chain is passed between the teeth of the sprocket.
  • The top of the guide bar must be moved into the groove of the bar that surrounds it.

Hold the guide bar against the chain saw body to install the clutch cover.

When the installation is finished, you can move on to setting up the Husqvarna 137 chain saw.

  • First you need to turn the switch on the saw to the “On” position.
  • Then pull the idle speed damper lever out as far as it will go.
  • Pull the starter cord with a firm hand (but no more than ten times).

If you hear the engine noise before you have done the 10 pulls, then you can go to the next step.

To start and tune an already warmed up engine, you need to:

  • Set saw switch to “On” position.
  • Point the mode change knob to the “HalfChoke” mark.
  • You have to pull the cord with your right hand until the engine starts.
  • Press the starter to bring the engine back to idle speed.

For disassembly and reassembly, see

Model Specifications

Husqvarna brand chain saw in the brand 142 has solid factory parameters.

  • petrol engine power. 2,58 l. с./1.9 kW;
  • idle / maximum rpm. 3000/13000 rpm;
  • The manufacturer recommends the length of the bar to be used. 30-38 cm;
  • Weight with fuel and oil tanks is 4.9 kg.

The Husqvarna motor is very quiet despite its impressive maximum rpm capability. Operator-acoustic output is up to 105 dB for maximum power output.

Chainsaw Reliability

The 236th model of Husqvarna is considered quite reliable, and if used properly, it does not cause problems for the owners. When the tool is not used and stored properly, the first thing that can fail is the carburetor.

Like all chainsaws equipped with two-stroke engines, the Husqvarna 236 is very sensitive to the cleanliness of the air entering the cylinder. In this case, if the owner of the tool doesn’t control the cleanliness of the air filter and change it in time, the saw’s CPG will fail much faster. This is a very serious problem, the solution to which is an overhaul.

READ Idle speed adjustment on the Husqvarna 137 chainsaw

For more information on Husqvarna chain saw malfunctions and how to fix them, visit this Husqvarna repair article on our web site. This article includes information on how to remove the cylinder, what to do if oil is leaking, or when the Husqvarna 236 starts and stops.

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I bought my chainsaw over 2 years ago. At first I was a little frustrated because I thought it was a little short on power, but after I visited the service center and adjusted the carburetor on the saw, the engine ran at full speed and the chainsaw greatly improved performance.

In all the time I’ve worked in the sawmill environment, the 236 has hardly ever broken down. I change the filter on time and try to keep the saw clean. After each work day, I clean it with a compressor. In my opinion this is what allows to work without breakage.

But there were more breakdowns. After a year of use I had to replace the starter cord, but I think that’s a small thing. There were also some starting problems, but they ended after I changed the fuel filter. In general I’ve never heard of such chainsaws starting badly.

I advise you to use only quality Husqvarna oils, because I use them and am very satisfied. Even for the chain lubrication I used a special glue oil and noticed that the bar and sprocket last much longer than my colleagues who save and fill up the used oil from car engines.

I recommend it to everyone, the chainsaw is worth the money spent on it.

How to properly adjust the carburetor of a Husqvarna chainsaw with your own hands

Like any machine, it needs periodic care and adjustment. Particularly due to poor-quality fuel. Let’s review the principles and procedure for adjusting the carburetor of a Husqvarna chainsaw.

How is a chainsaw carburetor set up, what principle does it work?

Today’s car engines no longer have a carburetor. And meanwhile, in the past, almost every driver knew how to adjust it. Today, chainsaws with injector engines have already started to appear on the market, but carburetor models will still long hold the palm, because their cost is 5-15 times lower than that of the modernized version.

The carburetor consists of several main parts:

  • aluminum housing;
  • fuel (float chamber) and air valve in the inlet;
  • nozzles (valves for adjusting the fuel supply);
  • Atomizer (it is the one that provides the injection);
  • fuel (float chamber).

How a chainsaw carburetor works is quite simple. fuel is fed continuously and the quantity of fuel is regulated by the nozzles. Air enters through the air damper due to air rarefaction, which is created by the piston. In the diffuser, fuel and air mix. It is this fuel-air mixture that enters the cylinder, making the engine run.

How to adjust the carburetor on a Husqvarna 240 chainsaw?

Every machine is subject to breakdowns from time to time. The Husqvarna 240 chain saw’s main malfunctions are related to carburetor repair, other parts of the fuel system, and malfunctions in the oil pump. If the oil pump fails, the chain for the Husqvarna 240 chain saw stops turning due to lack of lubrication. Damage to the gas tank or fuel hoses can also be the reason why the saw leaks gas. If the chain saw does not start at all, first check the quality of the fuel mixture and spark plug ignition. If necessary, clean or replace the spark plug with a new one and adjust the carburettor.

You may want to adjust the carburetor if your chain saw does not start up normally, cuts out when loaded, changes in fuel type, or cuts in operating conditions. Carburetor adjustment should be made after preliminary cleaning of air filters and warming up of the engine.

Then proceed as follows algorithm:

  • Screw L turned all the way to the maximum. Then immediately return the screw a quarter of a turn back.
  • While holding the throttle grip, turn the H screw a quarter turn.
  • Release the throttle and turn the screw T clockwise until the chain starts to move. After that, immediately turn the screw back until the chain stops.

A diagram of the location of the corresponding propellers is shown below:

How to adjust the carburetor on your Husqvarna chain saw

Modern chainsaws have a complex system and consist of several major components that require periodic maintenance and adjustment. In this article, we’ll talk about how to adjust the carburetor on a Husqvarna chainsaw.

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When the carburetor on your Husqvarna chain saw needs adjustment

Problems, the solution of which can be the adjustment of the carburetor, there are many. Adjusting the carburetor of your Husqvarna chain saw is necessary when malfunctions such as

  • increased idle speed;
  • Strong smoke formation during tool operation;
  • Difficulty in starting a cold or hot engine;
  • No thrust and reduced maximum rpm.

This is by no means a complete list of problems that can be solved by adjusting the Husqvarna carburetor. In some cases, adjustment of the quality and quantity of the fuel mixture is carried out after the engine overhaul or during regular service maintenance of the chain saw.

The manufacturer Husqvarna AB recommends adjusting the carburetor before and after running-in.

Design and operation of Husqvarna carburetor

To successfully tune your Husqvarna chainsaw carburetor you need to know its design and understand how it works. In fact, everything is not as complicated as it may seem at first sight.

The carburetor has a built-in fuel pump, which is responsible for transporting the gasoline-oil mixture, as well as a diaphragm, a needle valve, and a yoke. Their joint work allows to meter fuel to the main chamber and two flaps.

One of the throttle valves is designed to regulate the fuel flow into the cylinder when the throttle is depressed, it is called a throttle valve, the other is responsible for limiting the air supply from the air filter to facilitate starting a cold Husqvarna chainsaw. At the moment when the operator closes the air inlet to the carburettor with a choke, the fuel mixture is depleted and the fuel supply to the cylinder increases, making the chain saw much easier to start than when the cold start is made in normal mode.

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In the work of Husqvarna carburetor involves a nozzle valve, which atomizes fuel and prevents the flow of air into the main chamber. Often problems during the operation of the saw can be caused by defects in this element. For example, the valve, if the chainsaw is not stored properly can stick, the fuel supply will stop, making it impossible to operate the engine. Also, improper operation of the nozzle can cause air leakage into the carburetor’s main fuel chamber. In such cases, adjusting the position of the adjusting screws will not correct the situation, you need to repair or replace the unit.

Three adjustment screws in the carburetor housing are responsible for adjusting the mixture quality and quantity, as well as the number of crankshaft revolutions in idle mode:

  • Screw (L). adjusts the amount of fuel in low- and medium-rpm mode;
  • (H) is responsible for the high RPM pull and the amount of pull;
  • (T). adjusts throttle valve position to control mixture flow into the cylinder and idle run of the tool engine.

The (L) and (H) screws should not be adjusted without some knowledge and experience. Incorrect adjustment of the quality and quantity of the fuel mixture can lead to the fact that the engine will stop working or will not work properly, leading to rapid wear or even jamming.

The tools you need for the job

Before you start adjusting the Husqvarna carburetor, you must take care to have all the tools you may need. To do this type of work yourself, you will need:

  • screwdriver to adjust the screws (H) and (L), it can be bought in specialized stores;
  • An electronic tachometer to determine the readings of the crankshaft rotation frequency (having some experience, it is possible to make an adjustment by ear);
  • Phillips screwdriver, for adjusting the screw (T);
  • A compressor with a blow gun, for cleaning the saw before work.

An ordinary slotted screwdriver will not work for the adjustment, t. к. the adjusting screws on Husqvarna chain saws may have different cross sections. You have to buy a special, this is a feature of Husqvarna chain saw repair, they have made everything so that the saw can only be repaired in a specialized service center Husqvarna.

Algorithm and description of Husqvarna carburetor tuning

The Husqvarna carburetor is adjusted in the same way as the carburetors on chain saws from other manufacturers are adjusted.

Immediately before adjusting it is necessary to carry out a full diagnosis of the chainsaw and make sure that there is no fuel blockage or air intake into the carburettor. Also, make sure the air filter is clean and replace it with a new one if necessary.

Ремонт бензопилы Хускварна 142 (husqvarna 142). Замена и регулировка карбюратора. Натяжка цепи

  • The Husqvarna carburetor is set to the factory settings on the plugged-in saw.
  • The engine is started and the saw is warmed up for a few minutes.
  • By turning the screw (L) clockwise, the position is found at which the engine develops the maximum speed, after which the screw should be turned back to 1⁄4. If the chainsaw chain turns, it is necessary to reduce the idle speed by adjusting the screw (T).
  • The next step is to adjust the power of Husqvarna at maximum rpm and adjust the number of. For this purpose, the tachometer is connected to a running chainsaw, the throttle handle is pressed to full, and then the tachometer readings are checked. If the value of maximum revolutions differs from the maximum recommended by the manufacturer, then by changing the screw position (H) the tachometer readings are normalized.

Adjustment Considerations

After the adjustment the bar saw should be easy to pick up and drop down and should be stable in low and high rpm. If the chain rotates at idle speed after adjusting the carburettor control screws, it is a sign that the adjustment has not been made correctly and the carburettor control screw (T) needs to be readjusted.

Also, when adjusting the Husqvarna carburetor it is worth taking into account the chain saw’s response time to turning the screws. The settings are not changed immediately, but within five to ten seconds.

One indicator of an improper adjustment is heavy smoking when the saw is running, indicating a large amount of fuel entering the combustion chamber. If such a situation arises, it is necessary to correct the screw position (L).

Factory settings

Husqvarna carburetor default settings are (H) and (L) screw positions, where a good chain saw is guaranteed to start. For Husqvarna machines this is a turn and a half from the fully turned screws (H) and (L). During the adjustment process, first set the screws to the standard position, then start the chain saw and make fine adjustments to the power, maximum rpm and idle rpm.

Husqvarna Model 142 40cc Chainsaw Repair & Tune-Up ~ Will it Run?

Repair the carburetor with your own hands

If during a complete diagnosis of the Husqvarna chainsaw defects were detected in the carburetor, some of them can be repaired without going to the service center Husqvarna AB. For example, you can do it yourself:

  • Replace gaskets under main chamber and fuel pump covers;
  • clean or replace the strainer;
  • replace the main chamber diaphragm or needle valve;
  • troubleshoot the fuel pump diaphragm.

Gaskets, diaphragms and needle valve and rocker arm are available in the repair kit for each model of Husqvarna chainsaw carburetor.

Also, with some experience, you can try to repair the faulty valve injector, but it is impossible to guarantee a positive result when trying to repair the injector, if it is faulty, the manufacturers recommend changing the carburetor completely.

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The first thing to do, before removing the carburetor from the Husqvarna, is to clean the saw with a compressor, t. к. dirt can interfere with the quality of the repair. Next, you need to open the top cover of the chainsaw, remove the air filter, disconnect the levers from the control levers of the air and throttle valves. After that unscrew the screws fixing the carburetor.

To disassemble the carburetor body for repair is simple enough. The main chamber cover is held by four screws, which can be removed with a normal screwdriver, the fuel pump cover is secured with one wide screw.

Below is a video that will help you understand exactly how to repair the carburetor without calling a Husqvarna service center.

The work of adjusting or repairing the carburetor on Husqvarna chain saws can be done without some experience. To do everything correctly, you need to follow the algorithm and have a minimum set of tools. It is also worth assessing your capabilities beforehand and not taking chances if you don’t understand anything about the technique. Believe me, sometimes it is better to pay a small sum to a master, than to spoil a tool by adjusting it by yourself.

How the carburetor on a Husqvarna 137 chain saw works?

On chain saws of these models most often installed from the factory carburetor Walbro. Before adjusting the Walbro carburetor on the Husqvarna chainsaw, it is necessary to have a minimum understanding of its construction and know the principle of operation.

What controls the fuel and oil mixture

For precise fuel and oil supply it is possible to use the fuel pump that is mechanically driven by the crankshaft. The carburetor itself is equipped with a diaphragm and a special needle valve, which are responsible for regulating the pressure in the system. Thanks to them, the proper operation of the metering chambers and the pump is organized, which improves the performance of the chainsaw.

Fuel mixture preparation

When operating the chainsaw, a fuel mixture of gasoline and oil in a ratio of 15:1 by volume must be used, t. е. add 1 liter of oil to 15 liters of gasoline and mix the mixture thoroughly. The amounts of gasoline and oil in the fuel mixture are given in this table:

Gasoline.л 1 2 3 4 5 6 7 8 9 10
Oil, l 0.06 0.13 0.20 0,26 0,33 0.40 0.46 0.53 0.60 0,66
Fuel mixture, l 1.06 2,13 3,20 4,26 5,33 6.40 7.46 8.53 9.60 10.66

WARNING! Application of oils: Lukonoi-2T; TNK-2T OIL: AZMOL Sport 2T GD” and Dr., and waste oil in the fuel mixture will cause the connecting rod needle bearing to fail.

What is responsible for the air supply

The air supply is provided by two dampers installed on the diffuser chamber. The first can regulate the amount of air at the moment of pressing the gas pedal and is called throttle, and the second provides a limited air supply at the moment when you make a cold start chainsaw. In order to make starting easier, the choke is closed, which means that the mixture becomes richer because it is saturated with more fuel. This mode is easier to operate, but because it increases fuel consumption, it is not used throughout the day’s work. The saw is working hard.

To spray the fuel in the cylinders, a nozzle with a check valve is used.

The principle of operation is simple: it limits the return of mixture back into the chamber. All the main malfunctions of chainsaws, more often than not, are manifested by the improper operation of this mechanism.

  • The most common mistake is storing the tool for too long. The thing is that with prolonged idling the valve gets stuck and either fills the cylinder with fuel or simply does not open.
  • The second problem is an increase in the amount of air in the mixture, caused by sucking it from the outside, if the valve does not work properly. It is already impossible to adjust here, because in this case only the valve repair or its replacement will help, because the adjustment screws will not react.

In contrast to the car, adjustment of a chainsaw carburetor provides for three adjusting screws, responsible for the quality of the mixture, quantity and nominal revolutions of the crankshaft of the engine Husqvarna:

  • Screw L. is designed to adjust the number of revolutions when working in medium modes and regulates low revolutions;
  • H screw. adjusts the number of high revolutions and thrust of the unit;
  • T. designed to adjust the total amount of fuel and adjusts throttle operation.

It is not advisable to touch the first two screws if you are not qualified to do so. The problem is that if they are adjusted incorrectly, the carburetor will not be able to start the engine, or even start it in the wrong mode of operation. Such adjustment of the screw can lead to its rapid wear and failure. This principle is inherent in many devices.

The parameters of the settings are not listed in any table. So don’t look for this data in special literature, but just follow the instructions clearly. The table in the datasheet is for information only and has no reference to the engine’s performance.

No Start Chainsaw, How to bring a Husqvarna 142 back to life!


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