The chainsaw is an indispensable tool, both in the home garden and in the summer cottage. But even the most reliable “iron” assistant begins to mope, then it does not start, then it stalls. There can be many reasons, both related to the quality of the fuel mixture and the engine..
There are a lot of nuances, we will not consider all of them in this article. And we will “take a closer look” at that part of the engine, which is called the carburetor. And we will try to find the answer to the following questions: when is it necessary to adjust the carburetor of a chainsaw and, in fact, what is the scheme of such an adjustment.
When is adjustment necessary
In general, the need to adjust the carburetor of a Stihl chainsaw, or any other brand, arises quite rarely. Signs of a misaligned carburetor are indicated by:
- the engine starts and stalls, or does not start – in this case, the cause may be a “poor” fuel mixture;
- fuel consumption has increased significantly and there has been an increase in the amount of exhaust gases (fuel does not burn completely). oversaturated mixture may be the cause.
The adjustment itself gets lost in very rare cases, namely:
- when the fixation of the adjusting screws was broken, there are three of them. Vibration or damage to the protective cap may be the cause. It is quite rare that the screws have not been touched..
- in case of significant engine wear, namely piston. Then the factory settings are not suitable. In this case, adjusting the carburetor of a Patriot chainsaw, or another model, can save the situation for a while. But here it is time to think more about repairing the engine, rather than adjusting the carburetor of a Husqvarna chainsaw or the like;
- the reason may be due to the formation of a blockage in the carburetor, the reason may be poor quality gasoline, damage to the air filter or scale. In this option, in addition to adjustment, it is necessary to disassemble and flush the carburetor.
Chainsaw carburetor device
Before proceeding with the adjustment, you need to know the structure and principle of operation of the carburetor. This will help avoid many “complications”. So, to begin with, let’s recall the principle of operation of an internal combustion engine. The cylinder contains fuel, and when burned, a small “explosion” is created, which creates a lot of pressure. This pressure pushes the piston, the piston, when set in motion, rotates the crankshaft. Ultimately, the pressure energy is converted into torque, which drives the chain through the sprocket..
During normal operation of the engine, it burns up to 10 milligrams of fuel in each cycle. And the fuel mixture is prepared and supplied in the carburetor.
Thus, the purpose of the carburetor is to mix the combustible mixture with air in the required proportions. If these proportions are violated, the operation of the engine is disrupted. For example, when mixing little fuel comes in, but on the contrary a lot of air, then such a mixture is called “lean”. Conversely, if there is not enough air, but on the contrary there is a lot of fuel, then this is a supersaturated mixture. Both cases lead to malfunctions in the normal operation of the engine and require adjustment..
The carburetor consists of the following basic elements, and although the design may differ depending on the model, the design and principle of operation are approximately the same:
- the basis of the carburetor is a tube, which in its characteristics resembles a wind tunnel, an air flow enters through it; an air damper is located across the tube; by its position, it either increases the air flow or decreases it;
- the tube is constricted. a diffuser that increases the speed of the air flow just in the place where the fuel inlet is located;
- the fuel itself enters the air channel from the atomizer, into which it enters through the nozzle from the float chamber (indicated in the photo as a fuel needle);
- the float chamber itself serves as a kind of reservoir, the purpose of which is to ensure a constant fuel level at the entrance to the air channel.
The principle of operation of the carburetor is as follows. A fast air stream flows through the air channel, its speed will also depend on the position of the damper. The float level ensures the degree of opening of the fuel supply channel and depends on the position of the same air damper. The air flow passing through the diffuser picks up the incoming fuel and sprays it. At this moment, a mixture is formed, which is sucked through the intake pipe into the cylinder..
In the float chamber, the pressure level is approximately equal to atmospheric, but in the air channel it is rarefied. Due to the pressure difference, the fuel is sucked through the nozzle into the air duct. The more the air damper is open, the greater the air flow, and, accordingly, more fuel comes in. More fuel – engine speed increases.
This is how the carburetor works. There may be nuances in its structure, but knowing how the simplest carburetor works, you can always understand and determine the purpose of other elements.
Chainsaw carburetor adjustment
Although quite rare, carburetor adjustments may still be required. Immediately, we note that not everything can be done independently, unless you have a tachometer and at least once personally see how to do it correctly.
To adjust the carburetor of the Makita chainsaw, like most other models, there are three adjusting screws. Although some manufacturers have carefully removed two of them, leaving only one for the user’s experiments. So, three screws, on the carburetor body, they are indicated by the following letters:
- L – this screw is used to adjust low engine speed;
- H – high speed adjustment;
- T – to adjust the idle speed (it is left for experiments).
In general, the carburetors are already adjusted by the manufacturer for optimal operation, and the screws are designed for more precise carburetor adjustment of Champion chainsaws and others, in difficult climatic conditions such as high altitudes, etc. Since the air is thinner there, more precise tuning is required for the instrument to operate. Under normal conditions, this is not necessary..
To adjust the carburetor of the Goodluck chainsaw, as well as other brands, two screws L and H are used to create the appropriate quality of the fuel mixture. To create a lean mixture, the screws are turned clockwise, this allows you to increase the number of revolutions, i.e. thus, set high revs. Accordingly, when the screws are turned counterclockwise, the mixture turns out to be more saturated, this regulates the low number of engine revolutions. Thus, when adjusting the carburetor of the Partner chainsaw by turning the screws clockwise, we increase the number of revolutions, counterclockwise, we decrease.
With any adjustment of the carburetor of a Chinese chainsaw or other, a number of requirements must be observed:
- fine adjustment is always carried out with a warm engine (engine operation for at least 10 minutes);
- the condition of the air filter must be satisfactory, i.e. clean and not clogged;
- when rotating the chain with the adjusting screw T, it is necessary to achieve its complete stop, for this the screw is turned counterclockwise.
And do not forget about our own safety, the chain should be directed in the opposite direction to us, the saw should stand securely on a flat surface and not touch any objects with the cutting part. With fine adjustment, the screws are adjusted in the following sequence L. H – T. With the screw L it is necessary to “find” the maximum number of engine revolutions. To do this, turn the screw clockwise, or in the opposite direction, until we “grope” the maximum. This is where a tachometer is needed, or a sensitive ear for music, and you should know the sound of the engine speed limit, if you overdo it, especially with the H regulator, the engine will fail. Repair will cost a pretty penny, therefore we strongly recommend entrusting such work to a professional.
If you have a tachometer in stock and you know the maximum number of revolutions of your engine, then you can, at your own peril and risk, try to bring the adjustment to the end. It will look something like this: we find the closest value of the revolutions with the L regulator, then with the same regulators we return counterclockwise by a quarter of the screw turn. We leave and go to the regulator H, and if you tighten it too much, the engine will fail..
We turn this regulator by ¼ turn of the screw counterclockwise (the engine is warmed up before this). We listen carefully or orient ourselves to the tachometer. If to sound – our ideal, when the engine at maximum works like a four-stroke engine. If the mixture is too rich, the sound is squealing. You can try to achieve an average value, not have an ideal, but remove the squealing sound with a screw. And if the work of the saw suits you, it is better to leave it as it is, it is better than to be left without an engine..
If it was possible to more or less adjust the screws L and H, then there is little left – to adjust the idle speed. The ideal here is to ensure that the engine runs evenly in all positions until the chain starts to move. Turn this screw counterclockwise until the chain stops. If this cannot be achieved, the help of a specialist is needed. An unadjusted chainsaw is a very dangerous thing..
A well-adjusted carburetor is:
- idling chain “stands”;
- the engine accelerates quickly;
- engine operation resembles a four-stroke engine.
Below is a video of adjusting the chainsaw carburetor
Design and scope of use
Your Husqvarna 240 chainsaw goes beyond standard firewood functions. With its help, you can easily clear a large area of shrubs and old trees, form the crowns of ornamental plants in the garden, use it in construction for cutting boards. Sufficient power and length of the bar allow you to cut wood both along and across.
The classic design of the brand is combined in this model with high technical characteristics and ease of use. The Husqvarna 240 saw is in the household class, but its performance is not much different from professional tools. Manufacturers have provided in this saw such necessary functions as easy start, double air purification, vibration reduction. Ergonomic control levers and handle provide maximum comfort during operation and reduce operator stress. The main components of the mechanism are located in such a way as to speed up and simplify access to them in case of repair.
If you follow the operating instructions and regularly carry out preventive inspections of the chainsaw, repairs can in most cases be avoided. But even in the event of a breakdown, the tool will not cause you significant inconvenience – original spare parts can be easily purchased and replaced. The detailed structure of the Husqvarna 240 chainsaw is shown in the diagram below:
Chainsaw “Husqvarna 240”, the technical characteristics of which you can see below. it is equipment that follows the Husqvarna 236 mowing line. If a comparison is made between the two, it should be noted that the latter has higher horsepower, a slightly longer tire and has an engine that saves fuel up to 25%..
The Huskvarna 240 chainsaw, which does not need to be repaired very often, is an environmentally friendly tool, which is very important for some consumers. The volume of harmful emissions into the atmosphere decreases, and the number of cuts on one fuel for refueling increases. Quite often, the products of the aforementioned Swedish company are compared with the manufacturer of the Stihl chainsaw. As an advantage of the former, it should be noted that a primer is available to facilitate start-up. However, as practice shows, this does not have a significant effect on the equipment startup process..
Chainsaw specifications Husqvarna 240
At the heart of the Husqvarna 240 is a 2-stroke engine with carburetor. Works on a gasoline-oil mixture. The service life has been increased due to improvements in the crank assembly and a special coating of the cylinder. Fuel economy is reduced by 20% thanks to the innovative X-Torq system, which also reduces the harmfulness of exhaust gases. Capacious fuel tank and low fuel consumption extend the operating time of the tool, without interruption for refueling.
The rest of the saw has the following technical characteristics:
- productivity – 2 liters. from.;
- chain pitch – 3/8 inch;
- fuel tank capacity – 300 ml;
- oil tank – 200 ml;
- tire length – 40 cm;
- weight – 4.7 kg.
Tools required for work
Before proceeding with the tuning of the Husqvarna carburetor, you need to take care of having all the tools that may come in handy. To carry out this type of work yourself, you will need:
A regular slotted screwdriver will not work for adjustment, as the adjusting screws on Husqvarna chainsaws may have different cross-sections. You will have to purchase a special, this is a feature of repairing Husqvarna chainsaws, they did everything so that the saw could be repaired only in a specialized Husqvarna service.
Algorithm and description of setting the carburetor Husqvarna
Husqvarna carburetor, adjustable in the same way as carburetor settings on other brands of chainsaws.
Immediately before adjusting, it is necessary to carry out a complete diagnosis of the saw and make sure that there is no obstruction of the fuel supply and air leakage into the crankcase of the chainsaw. It is also necessary to make sure that the air filter is clean and, if necessary, replace it with a new one..
The order of work is as follows:
- Saw muffled with Husqvarna carburetor factory setting.
- The engine starts and the saw warms up for a few minutes.
- By turning the screw (L) clockwise, the position is found at which the engine develops maximum speed, after which the screw must be unscrewed 1⁄4 back. If at the same time the chain of the chainsaw rotates, then it is necessary to reduce the idle speed by adjusting the position of the screw (T).
- The next stage is adjusting the power of Husqvarna at maximum speed and adjusting their number. To do this, the tachometer is connected to a running chainsaw, the throttle stick is squeezed out to full, after which the tachometer readings are checked. If the value of the maximum revolutions differs from the maximum number recommended by the manufacturer, then by changing the position of the screw (H), the tachometer readings are returned to normal.
How to adjust the carburetor on a Husqvarna 240 chainsaw?
Any technique is subject to breakdowns from time to time. The main malfunctions of the Husqvarna 240 chainsaw are associated with the repair of the carburetor, other components of the fuel system, and malfunctions of the oil pump. If the oil pump breaks down, the chain for the Husqvarna 240 chainsaw stops rotating due to lack of lubrication. Also, damage to the gas tank or fuel hoses can be the reason why gas is leaking out of the saw. If the saw has completely stopped starting, first of all you should make sure of the quality of the fuel mixture, check the spark plug spark. If necessary, clean the spark plug or replace it with a new one, adjust the carburetor.
Adjustment of the carburetor is also required in cases where the chainsaw began to start poorly, stall under load, and also if the type of fuel or operating conditions have changed. It is worth adjusting the carburetor after pre-cleaning the air filters and warming up the engine.
Then proceed according to the following algorithm:
- Screw L turns to the maximum. Then immediately return the screw a quarter of a turn back..
- While holding the throttle grip, turn screw H a quarter of a turn.
- Release the throttle and turn the screw T clockwise until the chain starts to move. Then immediately turn the screw back until the chain stops..
The location of the corresponding screws is shown below:
Modern chainsaws have a complex system and consist of several main units that periodically require maintenance and adjustment. In this article, we’ll talk about how to adjust the carburetor on a Husqvarna chainsaw..
Do-it-yourself adjustment of the carburetor of the “Husqvarna” 240 chainsaw
Correct installation of the carburetor circuit is the key to stable operation of not only the engine, but also all other systems of gasoline technology. It is based on the 3-jet principle:
- jet “T” is responsible for idling;
- “N” – for high speed;
- “L” – low speed screw.
DIY Husqvarna 240 chainsaw carburetor adjustment
Adjusting and adjusting the carburetor Husqvarna 137
husqvarna137 carburetor adjustment
In the picture above, you can see three adjustment screws. Each of them has its own purpose:
The T screw is required to adjust the idle speed.
Screw L is used to adjust low rpm.
Screw H adjusts high rpm.
First, with the L screw (rotating it), we look for the highest idle speed. After we have found them, it is necessary to turn this screw a quarter of a turn against the clock hand. If in this position the chain continues to rotate, then by rotating the screw T we achieve its stop.
Then we warm up the engine at full speed in the region of 10-15 seconds and turn the screw H a quarter counterclockwise. We wait 10 seconds and listen – the engine should work like a 4-stroke in sound. If a squeal is heard, then the mixture is poor (unscrew the screw), if the enriched mixture smokes (tighten the screw).
After adjusting the low and high speeds, we set the idle speed with screw T. This is done as follows:
Husqvarna 240 Chainsaw
1.The engine must be running
2.Turn the screw T clockwise until the chain starts to rotate.
3.Rotate the screw in the other direction until the chain stops.
Husqvarna 240 Chainsaw Carburetor Replacement
With a properly adjusted carburetor, your chainsaw quickly picks up speed and sounds like a 4-stroke engine..
Remember that a tachometer and experience are required to properly adjust the carburetor of your chainsaw. Therefore, it is better to contact a specialized service.!
- Power – 1500 W;
- Fuel tank – 300 ml;
- Carter – 0.2 L;
- Tire – 400 mm;
- Step – 3/8;
- Weight – 4.7 kg.
Advantages of the Husqvarna 240 chainsaw:
- active vibration damping system “LowVib”;
- equipping the front handle with additional protection;
- inertial brake;
- chain catcher;
- lubrication of the saw unit in the “Automatic” mode;
- “X-Torq” technology, which reduces fuel consumption and the amount of gas and dust emissions into the atmosphere;
- functional “Air Injection” – 2-circuit air purification;
- multi-tasking control lever;
- electronic ignition;
- capacious reservoirs for life support of a motorcycle tool;
- reinforced piston-cylinder;
- ergonomic design;
- acceptable price for those who value quality and durability.
Do-it-yourself carburetor adjustment on a chainsaw
Chainsaw carburetor adjustment ensures efficient operation of the tool at full power while saving fuel. Adjustments must be made with a clean fuel and air filter. For a larger number of carburetors, the adjustment is carried out with three screws: for maximum and minimum revolutions and idle speed adjustment.
The H and L screws adjust the ratio of the mixture of gasoline and air, which is determined by opening the throttle valve of the carburetor. When the screws are unscrewed, the mixture is enriched, and the revolutions accordingly fall, when the screws are tightened, the mixture becomes leaner – the revolutions grow.
Designation H refers to the maximum speed screw that controls the main jet, L refers to the minimum speed screw that controls the idle jet. The S screw is used to fine-tune the idle speed. Sometimes, to simplify tuning, the number of available carburetor adjusting screws is reduced..
Chainsaw carburetor tuning is divided into two stages – basic (factory settings), carried out with the engine off. and the final, produced on a running warm engine. The exact value of the angles of rotation should be taken from the operating instructions for the particular chainsaw. Failure to follow the manufacturer’s instructions may result in engine damage.
Basic carburetor adjustment.
The adjusting screws for maximum H and minimum L turns are slowly turned clockwise until they stop, then turned back 2 turns, other settings are also possible
Checking and adjusting idle speed.
We find the highest idle speed, for this we slowly turn the screw L in different directions. After finding the position of the highest engine speed, turn the screw L 1/4 turn counterclockwise. If the chain rotates at idle speed, screw T or (S) should be turned clockwise until it stops..
Checking and adjusting the maximum speed.
The maximum number of revolutions is changed by screw H. When screwing it in (clockwise rotation), the revolutions increase, when turned out, it decreases. Chainsaw engines have the highest rotation speed of 11500 rpm. up to 15,000 rpm. A higher speed does not provide ignition, moreover, it becomes dangerous for the engine. The rpm limit can be determined by misfiring. If they come, turn the screw H slightly counterclockwise..
If the engine is not checked for acceleration and maximum speed, then the adjustment of the chainsaw cannot be considered complete..
When the throttle trigger is smoothly pressed, the engine should confidently and quickly gain speed from idle to maximum (from 2800 rev. To 11500-15000 rev. Depending on the unit). If revolutions are gained slowly, with a lag, screw L must be slowly unscrewed counterclockwise, but no more than 1/8 of a turn..
After adjusting the acceleration and maximum speed, check the saw operation at idle speed again – the engine should run stably, the chain should not move. Chainsaw tuning should be repeated if this condition is not met but with the exception of the basic adjustment step.
Chainsaw Husqvarna (Husqvarna) 137. carburetor adjustment.
The best advice that I can give you is to contact the specialists! Believe me, for very little money, specialists will adjust the carburetor, check the general condition of the saw. But if you still need to adjust the carburetor on the Husqvarna 137 saw yourself, then I will try to describe this process in detail. Also at the end of the post I added a video on how to adjust the carburetor of a chainsaw at idle.