Cleaning and adjusting the chainsaw carburetor. Chainsaw carburetor adjustment Champion: what you need to know? Rechecking at idle speed

For a small, compact chainsaw mechanism, the calm 250, the correct carburetor setting plays a key role. All well-coordinated work, all load modes and its trouble-free operation directly depend on the adjustment of the fuel supply systems, the quality and quantity of the fuel-air mixture. This article describes how to adjust the carburetor for calm 250 and set up all of its dosing systems.

Carburetor device

In fig. 1 shows a modern carburetor for a chainsaw made in Germany “Calm 250. It is a unit the size of a half of a human fist. The movement is manufactured by Walbro, Taiwan. Case material - stainless steel alloy. At the bottom of the device, a flap is fixed, which ensures a uniform supply of the fuel-air mixture to the engine combustion chamber.

Rice. 1. Carburetor for the "Calm" chainsaw.

Holes are also made here for attaching the unit to the body of the power unit. A sealing gasket is installed between the flanges of the mixture supply and the combustion chamber of the engine. An accelerator pump is located under the throttle stem. It is a small piston with a rubber ring.

The front of the case houses a series of easy-to-use spring-loaded adjusting screws:

• idle move;
• maximum speed;
• the amount of the mixture;
• the quality of the mixture.

It is these screws that adjust the carburetor of the chainsaw calmly.

The main innovative feature of the calm 250 chainsaw carburetor is the heating device. To prevent the mechanism from freezing during operation during the winter period, it is equipped with a special system that preheats the steel body during operation. For this, the unit is switched to winter operation mode.

The body is blown with heated air sucked in from the engine. This mode of operation of the mechanism prevents icing, freezing of the nozzles, and ensures the normal supply of the fuel-air mixture. When switching to summer operation, the hot air damper is closed. Summer mode is characterized by natural cooling of the unit.

Chainsaw characteristics calm 250

Need for adjustment

Throughout the entire operation process, the need for additional adjustment and ensuring the correct supply of the fuel-air mixture periodically arises. How to determine exactly when and what setting needs to be done for the equipment to function normally? There are characteristic signs when the mechanism, according to the behavior of individual parts, itself suggests when adjustment is necessary.

First of all, each time before starting the engine again, it is necessary to check the color of the spark plug electrodes.

By changing it, you can make a decision about the need to adjust, adjust work processes, improve the quality of the combustible mixture:

1. 1. Black electrodes covered with soot or carbon deposits indicate an over-enriched air / fuel mixture entering the engine.
   2. Brick-gray electrodes indicate that the mixture is ideal in its composition and no additional adjustments are required.
   3. A white coating on the spark plug electrodes indicates that the mixture is lean.

The signs outlined in paragraphs 1 and 3 indicate that for a calm 250 chainsaw, carburetor adjustment is extremely necessary.

NOTE! The owner may need to adjust the carburetor calm 250 with his own hands if the quality of the fuel, the height above sea level have changed, or if a vacuum occurs at the place where the chainsaw is used. It is possible that the air humidity, temperature, atmospheric pressure have changed.

Precise settings will allow you to achieve maximum performance of the unit while reducing the external necessary conditions for its operation. Successful debugging of operating conditions prevents oil starvation and engine failure due to insufficient lubrication. After all, the lubricant enters the saw cylinder along with the lean air-fuel mixture.

Preparing to adjust the carburetor

Of paramount importance in setting all the characteristics of the fuel dosage of the calm 250 model is the uppermost adjusting screw located near the muffler. The factory setting, the parameters of which are shown on the upper plastic cover, provides that it should be unscrewed one turn from full twist.

Throughout the operation process, the carburetor of the chainsaw calm 250 is adjusted with your own hands. Unscrewing the screw makes the working mixture richer, since the air-fuel mixture receives more gasoline, and tightening the screw makes the working mixture leaner, since the air-fuel mixture receives less gasoline.

Carburetor adjustment will not give positive results if air is leaking from the engine side through:

• carburetor gasket;
• rubber ring of the accelerating pump;
• crankshaft oil seals.

Calm 250 carburetor adjustment is carried out only after a careful examination, identifying existing air leaks. The next stage of preparatory commissioning is full maintenance of all units and mechanisms.

This includes:

• cleaning from deposits, slags, resins;
• washing the engine using a solvent, acetone;
• replacement of the spark plug;
• cleaning, washing the air filter;
• checking the tension of the cutting chain;
• idle setting;
• warming up the engine to operating temperature.

Then you can start complex manipulation of the settings.

Chainsaw carburetor adjustment calm 250

Rice. 2. Adjustment of the Stihl 250 chainsaw carburetor.

Step-by-step adjustment of the Shtil MC 250 carburetor with a revolution counter is carried out in the following sequence:

1. Switch off the engine, screws H and L should be tightened up to the stop, then unscrew both one turn.
2. Start the engine, warm it up. At maximum speed with screw H, achieve a maximum crankshaft frequency of 14,000 rpm, recorded by a tachometer or an engine revolution counter. Hold the maximum engine speed for no more than 10 seconds.
3. Using the bolt LA of the idle speed stop, achieve the start of the chain movement. Then turn bolt LA ¼ turn counterclockwise.
4. Check the acceleration of the Stihl 250 chainsaw mechanism. The carburetor adjustment continues if the idle speed is unstable or the chainsaw does not accelerate enough. Screw L must be turned slightly counterclockwise. At the same time, the saw should quickly gain momentum, function stably at idle speed. Make final adjustments with the LA screw. According to the tachometer, the idle speed must correspond to the catalog value of 2800 rpm.

Similarly, do-it-yourself adjustment of the Stihl 211 chainsaw carburetor.

In his article, the author highlighted in as much detail as possible all the details of adjusting the familiar mechanism made in Germany called the Stihl 250 saw. Adjusting the carburetor is simple and accessible to every home craftsman. Following the recommendations set out by the author of the article, everyone can set up their Stihl 250 chainsaw and enjoy its flawless operation.

Fuel Ratio

Engine oil for STIHL 2-stroke engines 1:50:

1:50 = 1 part oil + 50 parts gasoline

other branded motor oils for two-stroke engines of vehicle classification:

1:25 = 1 part oil + 25 parts gasoline

Examples of fuel mixture ratios:

If you have any questions about adjustment, watch the video instructions for adjusting the carburetor on the Stihl 230 and 250 chainsaw:

A chainsaw is a tool equipped with a two-stroke engine that requires carburetor adjustments from time to time to function properly. Standard or factory adjustment and tuning of the chainsaw carburetor is carried out in production, during the assembly of the tool. However, for stable operation and good performance, it is necessary to adjust the carburetor of the chainsaw during break-in.

After and during the break-in process, the owner's task is to properly adjust the carburetor for the most efficient, safe and durable operation of the chainsaw engine.

Do-it-yourself chainsaw carburetor adjustment - video using the Husqvarna saw as an example:

The main reasons for adjusting the carburetor of the chainsaw:

• gasoline consumption has increased, the device consumes too much oil;
• during operation, the chainsaw heats up very much, smokes, makes pops or explosive sounds (such a problem is a signal that you need to clean the muffler, blow out the breather, rinse the jets in acetone);
• the engine stopped idling;
• the chainsaw begins to stall some time after work, in general, the tool has become worse to work - it does not develop power so effectively, does not develop maximum speed;
• the chainsaw vibrates strongly during operation;
• it is also necessary to adjust the carburetor if the chainsaw has previously operated on low-quality fuel or on an improperly prepared fuel mixture.

Chainsaw carburetor setting:

What tool is needed to adjust the carburetor

To set up and adjust the carburetor, the following tools are used:

• tachometer (a special device for adjusting the carburetor, with its help the owner of the chainsaw can determine what is the maximum number of engine revolutions for a given model, and then make a correction according to the manufacturer's recommendations);
• an adjusting key (a special tool, which is often available only in service centers, is not supplied with chainsaws, since it can be used by inexperienced users, which will not lead to adjustment, but to the breakdown of the chainsaw).

Note: adjustment and adjustment of the carburetor of a chainsaw of any model, as well as its repair, should be carried out only by specialists of the service center while the tool is under warranty.

Independent attempts to clean the carburetor, flush and eliminate existing faults may not give the desired result.

Overview of tools for adjusting the operation and repair of the chainsaw carburetor:

Theory and principles of the fuel system, carburetor design

How the carburetor works

In different models of chainsaws, the structural device of the carburetor may differ, however, the principle of operation of this part is always the same: the forced air flow moves in the direction of the air (pulse) channel, the air is regulated by the air damper. Entering the impulse channel, the air changes its speed. The speed change is influenced by a special valve that closes the air intake hole. Fuel is supplied to the air duct and mixed with the air flow. As a result, a combustible fuel-air mixture is formed, which then enters the engine and burns there.

Figure 1. Diagram of the principle of operation of the chainsaw carburetor

Diagram of the principle of operation of the chainsaw carburetor

Figure 2. Husqvarna 137 chainsaw carburetor

Figure 3. The principle of operation of the fuel system on the example of the carburetor of a chainsaw with a two-stroke engine

The principle of operation of the fuel system on the example of the carburetor of a chainsaw with a two-stroke engine

The main task of the carburetor is the continuous and high-quality operation of the engine.

The constituent parts of any carburetor are:

• aluminum body (one-piece, cast);
• jets or valves that regulate the amount of fuel entering the carburetor;
• float chamber;
• diffuser;
• spray.

On picture 1 you can see the location of the key carburetor nodes, and in Figure 2 you can see the appearance of the chainsaw carburetor. To properly adjust the carburetor, the owner of the chainsaw should know how this part works:

• when the engine starts, the air damper opens;
• due to the piston stroke, rarefied air is formed inside the float chamber and in the air channel;
• then the mass of air is sucked in through the diffuser, where it mixes with the fuel that also passed through the nozzle into the float chamber, this is how a fuel-air mixture appears that enters the inlet channels;
• the last stage is the ingress of the mixture into the combustion chamber of the engine.

By adjusting the throttle position, the owner of the chainsaw can either add air to the fuel or deplete it - this means that the fuel mixture will enter the combustion chamber faster or slower. The carburetor adjusting screws are used to adjust the engine speed. An air filter is installed above the carburetor, which cleans the air before it enters the air channel.

A video in which a table is presented for adjusting the carburetor of a Husqvarna chainsaw:

Figure 4. Table of proportions of oil-fuel mixture for Husqvarna chainsaws

Table of proportions of oil-fuel mixture for Husqvarna chainsaws

Step-by-step sequence of the adjustment process

Before proceeding with the adjustment, remember:

• adjustment is carried out only "hot", that is, the engine must be started and warmed up for 10 minutes;
• then the adjusting screw is turned counterclockwise and the chainsaw chain is stopped;
• before adjusting the chainsaw, put it on a flat surface, and direct the saw part away from the owner;
• for adjustment, three screws with letter designations are used, H - adjusts the upper speed, controls the main jet, L - adjusts the idle jet, adjusts low speed, T - adjusts the idle speed.

Adjusting the carburetor step by step:

• turn screw L from left to right, or from right to left, find the limiting engine speed, then go back 1/4 of a turn;
• do the same with screw H;
• the chainsaw should work for a few seconds, using a tachometer, determine the maximum engine speed - their indicator should not exceed the maximum specified in the instructions for the chainsaw;
• if the chain moves in idle mode, turn screw T in the direction of chain movement until the chain stops completely (idle speed is always controlled only by screw T, which is rotated from right to left - counterclockwise - until the chain stops completely).

If the carburettor is adjusted correctly, the engine will accelerate quickly, the engine sound will be clear and rhythmic, and the chain will not idle.

Why can adjustments be ineffective?

• the threaded fasteners are loosened, air penetrates through the formed gap;
• the jets are clogged with resinous deposits, rinsing in acetone is required;
• the ignition is not adjusted.

Features of setting up Chinese chainsaws

Chinese chainsaws, especially newer models, may have some nuances in carburetor settings. Here are the main features:

• to adjust the carburetor of a Chinese chainsaw, you first need to set the idle mode so that the chain does not move along the tire;
• in the medium speed mode, a smoky exhaust may appear, it is removed by turning the lean mixture screw;
• the maximum number of revolutions of the chainsaw engine must not be exceeded (use a tachometer);
• if you adjusted the carburetor on a Chinese chainsaw correctly, when the gas is reset to a minimum, the device will not stall, and it will also quickly develop speed.

Video about adjusting the carburetor of a Chinese chainsaw

Video about adjusting and tuning the chainsaw carburetor

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 motor has a special device - a carburetor.

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

The device and principle of operation of the carburetor

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

• hulls;
• diffuser, which is located at the entrance to the device;
• jets;
• valves that regulate the supply of the mixture;
• special spray;
• float chamber.

The device has 2 or 3 adjusting screws equipped with springs. There are cone needles at the end of the screws.

Chainsaw carburetor working principle:

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 goes through the nozzles, then it is cleaned by a filter and enters through the damper located at the inlet of the diffuser.
4. In this case, a special flap, 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 pointed cone valve. The operation of this valve is regulated by a membrane that controls the flow of the mixture into the chamber. The operation of these units depends on the rotation of the internal combustion engine. The mixture is cleaned with a filter.

When adjustment is needed

Carburetor adjustment must be performed:

1. If the settings are lost due to loose screws or vibration, or when trying to adjust the device.
2. If the case cover breaks.
3. To find out the reasons why the structure does not work.
4. When the engine does not turn on or goes with an effort, and then immediately dies out.
5. When the chainsaw shoots the carburetor or sneezes.
6. The chainsaw vibrates violently.
7. To check why the fuel was overrun.
8. When there is a thick exhaust.
9. If the device does not receive gasoline.
10. When the spark plugs are blackened or coated.
11. The saw cannot serve at high speeds and increase power.
12. Checking the engine if it turns off when accelerating.
13. The operation of the air cleaning units was disrupted.
14. Debris has entered the mixture distribution system.
15. The pistons are worn out.

It is also necessary to carry out the adjustment when changing the type of fuel and changes in humidity.

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).

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

It is important to know how the tuning is done 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 L screw 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 to 1/4 turn counterclockwise. Then the idle speed is corrected 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 starts moving. Then adjust S 1 / 8-1 / 4 turn back. If the chain moves, turn the S screw 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, they test the operation of the device at idle. When the adjustment is done correctly, then the structure should not perform work like this:

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

If these requirements are not met, then it is necessary to adjust the idle speed. 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 adjustments are made using the 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.

Malfunctions and their elimination

Do-it-yourself chainsaw carburetor repair allows you to eliminate all problems that arose during the operation of the device.

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

Then check the setting of the screw H. Accelerate the motor to the maximum. Observe the exhaust and how the engine is spinning. 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 saturated. The highest engine speed is less than normal. Carbon deposits form in it. With such a problem, you need to scroll a little clockwise H. Then they monitor the operation of the motor and, if necessary, repeat the setting.

If the saw squeals, it means that the engine is overheating, the exhaust is cracking, and there is a misfire. This means that the mixture is unsaturated, and the highest engine speed is more than normal. This leads to overheating of the engine, combustion of the piston, cylinder and candle burnout. If such a problem occurs, to adjust, turn H 1/4 turn counterclockwise.

If the fuel does not go into the combustion chamber, such a problem is caused by a clogged fuel filter, jets or instrument ducts. To eliminate the malfunction, you will need to completely disassemble the filter and purge these channels with a compressor. Carburetor fluid is used to clean the channels.

It so happens that fuel overflows in the carburetor. This happens if the membrane is out of order, dried out and hardened, began to put pressure on the rocker arm attached to the needle. Then the needle is adjusted. To change the membrane, the carburetor must be removed.

The motor runs intermittently, 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 with detergents.

How to remove the 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. Remove the top cover. To do this, unscrew the bolts (3 pieces), which are located around the perimeter of the cover.
2. Remove the carburetor filter.
3. Then they turn off the gas supply hose.
4. Disconnect the traction of the motor drive.
5. Unscrew the cable connection tip.
6. Carefully remove and pull out the gasoline supply hose.

DIY disassembly

Dismantling the carburetor of the Homelite chainsaw is done as follows. Prepare a place - a flat surface. You will need the following tools:

• a 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 that is 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 troubleshooting and non-working parts and assemblies are replaced. The device is washed with a special liquid, dried, wiped with a dry cloth. Tubes and nozzles are blown out with compressed air. Before this, they are treated with ultrasound to remove plaque.

How to clean

When carrying out work with your own hands, you need to roughly know how to clean and rinse the carburetor. Flush the device as follows:

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

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

Stable stable operation at any speed, developed power, efficiency, the use of technical capabilities in the amount provided and laid down by the manufacturer, and even the service life of a chainsaw - all this depends on its carburetor. In addition to the fact that this unit also needs to be kept in proper condition and serviced in a timely manner, it also needs to be properly adjusted. Setting up the carburetor of a chainsaw is not an easy task, but with a leisurely thoughtful approach and strict adherence to instructions, almost anyone can do it, and it should be carried out at the first sign of the need for this, and regardless of whether the new chainsaw is in operation or well-worn.

In what cases are the chainsaw carburetor adjusted?

The following reasons, symptoms and malfunctions indicate the need to adjust the fuel supply unit (hereinafter referred to as the UTP, that is, the carburetor):

• factory or custom settings were knocked down due to loosening of the adjusting bolts and vibration, or in the process of unsuccessful attempts to adjust the carburetor with a new one;
• the cover of the UPT case is damaged;
• the engine does not start or starts with an effort, and then stalls almost immediately;
• the saw does not work steadily at idle or does not hold them at all;
• excessive fuel consumption and too thick exhaust;
• spark plug electrodes are black (feeding a re-enriched mixture to the engine) or with a white coating (depleted);
• the chain saw does not develop maximum speed or power;
• the engine stalls during a set of revolutions;
• there is a strong vibration of the chainsaw;
• due to irregularities in the operation of the air-cleaning system, debris particles have entered the mechanism for distributing the air-fuel mixture;
• the piston group has significant wear - in this case, the DCC regulation is used as a temporary measure to make the operation of the tool more stable.

Naturally, when dirt gets into it, the fuel system must be flushed - adjusting the carburetor cannot solve this problem. A worn-out piston needs a major overhaul. However, in these cases, the setting is also performed.

It may also be necessary to adjust the DCS even when the brand or quality of fuel, atmospheric pressure, humidity and ambient temperature, altitude changes (when the place of operation changes from a plain to a mountainous area, it is due to the rarefaction of air, and vice versa).

Preparation for tuning, carburetor parts for its implementation and safety measures

Before adjusting the DCF, it is imperative to make sure that both filters (air and fuel) are clean. In addition, there should be no air leakage into the motor from the side (through oil seals, a gasket under the UPT or its accelerating pump, or elsewhere), otherwise it will not be possible to adjust the carburetor.

Almost any DCT is regulated by 3 screws:

1. 1. The main jet bolt, designated "H", used to set the saw motor to maximum speed.
2. 2. An "L" idle jet bolt used to set the idle speed. That is, to regulate idle speed.
3. 3. Bolt adjusting idle speed, designated by different manufacturers in different ways: "S", "LA" ( Stihl), "T" ( Partner, Husqvarna).

There are also carburetors with fewer adjusting screws. This is how manufacturers protect their products from unprofessional interference and at the same time try to simplify their customization.

Before starting the adjustment, you should carefully study the operating instructions attached to the chainsaw, especially the part where the angles of rotation of the adjustment bolts are given. This is an important condition that will allow you to make the adjustment, without going beyond the operating parameters of the engine, correctly.

For safe regulation during its implementation, the following rules should be observed:

1. 1. The tool must be stably placed on a flat surface of a rigidly fixed object (workbench, rack, table).
2. 2. The chain should be directed away from yourself and others present.
3. 3. Between the chain and any surrounding objects there must be a safe distance, which guarantees the impossibility of their mutual contact.

Adjustment in case of changes in the operation or operating conditions of the chainsaw

In such cases, you can adjust the carburetor on the chainsaw as follows. First, we launch the tool and warm it up for 10 minutes.

We begin to adjust the DCL by determining the position of the adjusting screw "L", at which the idle speed will be the highest. To do this, very slowly and smoothly turn this bolt in one direction, then in the other. And so several times until the desired position is found. After that, we turn "L" by 1 / 8–1 / 4 of a turn (the required value is indicated in the technical documentation for the tool) counterclockwise (hereinafter PRCHS).

Then we continue to adjust the idle speed with the screw "S" ("LA", "T"):

• If the chain is stationary after manipulating the bolt "L", then it is necessary to smoothly rotate "S" ("LA", "T") clockwise (hereinafter referred to as POChS) until it starts to move. Then we twist "S" 1 / 8-1 / 4 turn back.
• If the chain moves, we rotate "S" ("LA", "T") of the PRCHS until it stops, and then we twist "S" 1 / 8–1 / 4 of a turn in the same direction.

The engine should run smoothly. And we check it, how it accelerates. It is considered that the motor operates normally in acceleration mode if, when the accelerator is pressed smoothly, the revolutions in a short time and without "dips" increase to their maximum value. If the engine runs unevenly and / or accelerates poorly, then slightly - a maximum of 1/8 of a whole revolution - turn the "L" PRCHS. After that, it is necessary to carry out the above setting "S" ("LA", "T") again. We repeat these adjustments until the motor runs smoothly and accelerates well.

Now check the setting of the adjusting bolt "H". To do this, we accelerate the engine to maximum speed. Only it is impossible to drive it for a long time without load, you need to pause. We look at the exhaust and listen to the operation of the engine. If too much gray smoke comes out of the muffler, and the chainsaw makes a lot of noise, then the carburetor is making an excessively rich mixture. In addition, the maximum speed of the power unit is lower than it should be. And also carbon deposits will form in it. In this case it is necessary to slightly tuck the POCH "H". Then we again check the operation of the engine and, if necessary, repeat the adjustment.

When the chainsaw makes a squealing sound, the engine heats up very much, the exhaust is accompanied by a crackling and / or interruptions in ignition are heard, that is, there is a detonation - the mixture is too lean, and the maximum engine speed is higher than it should be. This leads to overheating of the power unit, piston burnout, rapid cylinder wear and spark plug burnout. In this case it is necessary to turn the PRCHS "H" by 1/4 turn.

At the end of the adjustment, we check the saw at idle speed. With a properly adjusted DCL, it should work like this:

1. 1. The chain is motionless.
2. 2. The sound of the engine is almost like a four-stroke.
3. 3. Pressing the accelerator leads to a quick set of maximum revs.

If these conditions are not fully met, use the "S" ("LA", "T"), as indicated above, or repeat the setting from the beginning.

This is a rough adjustment. For accurate, you need a tachometer. We do all the same, only we turn the adjusting bolts, focusing on the readings of this device. This will allow you to accurately and, most likely, the first time to adjust the carburetor, having achieved, depending on the setting of idle speed at the level of 2800-3300 rpm or higher and maximum - 11000-15000 rpm. Which ones should be set, you need to look in the technical documentation (operating instructions) for the saw.

Adjusting a partially or completely misaligned carburetor

After maintenance, such as disassembly and flushing, or previous unsuccessful attempts to tune, this assembly may become completely misaligned. So much so that the chain saw won't start at all. In this case, it is necessary to configure the device of the engine power system in 2 stages, conventionally called:

• basic - with the engine off;
• final - performed on a warm engine.

At the first stage, the adjusting screws "L" and "H" are slowly screwed in the POCHS until it stops. In this case, you do not need to make great efforts and try to tighten them. Then we turn both screws back - for many models of saws by 1 revolution. And for some - by 1.5 turns. There may be other settings as well. This must be clarified in the technical documentation for the chainsaw. For some models, the tip is printed directly on the cover of their case near the adjusting screws.

This will accomplish the recommended factory default carburetor setting. In this case, do not touch the "S" ("LA", "T") screw, unless of course it has already been turned. When it is already twisted, you will have to work with it. Slowly screw in the "S" PRChS until it stops.

Let's move on to the final stage. We are trying to start the engine. If there has been no manipulation of the "S" ("LA", "T") adjustment and the "L" and "H" are set exactly as recommended, then it should start.

If "S" had to be tightened for the above reasons, then the engine, most likely, will not start right away. After each attempt, it will be necessary to tighten this screw 1/4 of the POCHS turn and try to start the engine again. In the end, he has to earn.

Then we warm up the engine for 10 minutes. If, after starting it or during warming up, the motor is unstable or the chain starts to move, then slowly and carefully rotate the "S" ("LA", "T") PRChS. As soon as the engine starts to work steadily and / or the chain stops, we immediately stop the adjustment. If the engine stalls, then turn this screw by 1 / 8–1 / 4 (see technical documentation) of the POChS turnover.

In the process of warming up, the idle speed may begin to increase, then, again, it will be necessary to "S" ("LA", "T") start slowly turning the PRCHS until they become normal by ear. With the engine already warmed up, we continue to adjust the power system assembly, as described in the previous chapter.

Adjusting the carburetor after running the chain saw

After running-in on saws, only fine-tuning of the DCS is performed. To do this, you will definitely need a tachometer and technical documentation for the used one. The fact is that almost optimal settings have already been set at the manufacturer's factory. Just for running in the engine and grinding in other moving parts of the chainsaw, the carburetor is configured to prepare a slightly richer than the calculated optimal air-fuel mixture. Due to this, the maximum speed is slightly lower than the constructively laid down by the manufacturer and, in addition, the motor is better lubricated. Thanks to this, the engine running-in and the running-in of the remaining moving parts take place in a gentle mode.

Therefore, if there is no tachometer and / or reliable information (passport data) about the maximum speed and at idle, then you should not change the factory settings after running in, since this will not work correctly. And in general, fine adjustment in this case is not necessary - the chainsaw will work fine with the existing basic settings. And if you really do it, then it's better in a service center. It is recommended to entrust the jewelry tuning of the carburetor of a still completely new tool to specialists.

Fine adjustment

It is strongly recommended to mark the previous position of the adjusting bolts as accurately as possible before making fine adjustments on your own. This will allow, in case of an unsuccessful attempt, to return them to their place - to the basic factory settings. We start the regulation with the bolt "H". After setting the maximum speed, we check the idle ones. If they differ from normal, set them first with "L" and then with "S" ("LA", "T"). In doing so, we are guided by the rules and principles set out in the second chapter of this article. But we turn the adjusting bolts, focusing on the readings of the tachometer. Then we continue to tune the carburetor as described in the same chapter. We turn the screws, following the readings of the tachometer.

How to tune Stihl chainsaw carburetors of popular models

Chainsaw carburetor adjustment Calm 180, 170 and other low-power ones are made with only one screw - "LD". They are set to idle speed.

The basic default setting is as follows:

1. 1. Fully tighten the "LD" PRChS until it is firmly seated.
2. 2. Then we turn it back to the POChS by 2 turns.

If you need to make additional or other adjustments, then first you need to warm up the engine for 10 minutes. Then if:

• idle speed is too low - turn "LD" POChS until the chain starts to move, after which we turn this bolt 1/2 turn back, PRChS;
• the tool chain moves at idle speed - slowly turn the "LD" PRChS until it stops, after which we turn this bolt another 1/2 turn in the same direction.

And it is better to tune with a tachometer, not forgetting that the chain should not move at idle speed. Maximum idle speed of models Calm 180 and 170 - 13500 rpm. Idle - 2800 rpm.

Adjust the chainsaw carburetor Calm equipped with a more powerful engine is produced in the same way as described in the previous chapters. This also applies to the most popular models such as Calm 210, 230 and 250 ... For the basic setting (discussed in the third chapter) "L" and "H" after tightening are turned back 1 turn. There are also carbureted saws that have a basic "H" setting of 3/4 turn. By the way, this information is indicated on the cover of the instrument body.

The angle (step) of rotation of the adjusting bolts during the DCL adjustment is 1/4 turn. Idling models Calm 210, 230 and 250 - 2800 rpm, maximum no load - 13000 rpm.

A chainsaw is a technically complex tool that needs to be serviced from time to time. Cleaning, replacing filters and, of course, adjusting the carburetor of the chainsaw will help to serve its entire life. In this article, we will consider the issue of tuning the carburetor. How and why it is carried out.

New chainsaws are supplied from the manufacturer with pre-adjusted carburetors. This is called standard adjustment. But for the normal passage of the process, it is required to lower the maximum engine speed, adjust the carburetor. After running in, the chainsaw needs to be fine-tuned to maximize engine performance.

Also, a signal for cleaning and adjusting is an increased fuel consumption, which negatively affects the operation of the exhaust system. Simply put, the chainsaw starts to smoke heavily and the muffler becomes clogged with carbon deposits, which in turn will lead to a decrease in power. With a lack of fuel in the mixture, engine parts are poorly lubricated and premature wear occurs. Also, a poor-quality mixture can cause the engine to jam due to overheating (this is one of the reasons why).

Adjustment is necessary when the engine does not idle, stalls or does not develop full power.

Carburetor tuning should be done with clean air and fuel filters.

Instruments

Correct adjustment of the chainsaw carburetor should be carried out using a special tool - a tachometer. It allows you to most accurately determine the maximum number of engine revolutions and adjust them according to the manufacturer's requirements. A small slotted screwdriver is required for adjustment. For some models of chainsaws, you will need a special adjusting key, without which work cannot be carried out.

The key for adjusting some models of carburetors is available only in service centers authorized for the repair of chainsaws by the manufacturer. This measure is aimed at reducing breakdowns due to incorrect settings by inexperienced users and those who are engaged in repairs without official permission to do so.

Setting up the chainsaw, if possible, should be carried out in official service centers that have a certificate from the manufacturer.

How the carburetor is adjusted

The algorithm for setting up the chainsaw is quite simple and consists of the following steps:

1. Regulation of the engine for smooth operation at low rpm.
2. Setting the carburetor for the correct fuel mixture at maximum speed.
3. Fine adjustment of the carburetor for idling.
4. Chainsaw check in all modes.

Carburetor adjustment should be done after the engine has run a little and warmed up.

Now let's look at how the correct adjustment of the chainsaw carburetor goes in more detail. Almost all carburetor models have three adjusting screws. The screw (T) is responsible for fine tuning in idle mode. Screw (H) setting for maximum speed. The screw (L) regulates the formation of the mixture at low rpm. By tightening the screws (L) and (H), the fuel supply and the mixture becomes leaner, respectively, the revolutions increase.

Process description

If the carburetor of the chainsaw is not adjusted and it is not possible to start the chainsaw, then the adjustment starts by setting the screws (L) and (H) to the standard setting. This is 1/5 turn of the screws until they are fully tightened. After that, you need to start the engine, let it run a little and warm up. The next step is to set up the low speed mode. Optimum low engine performance can be achieved by adjusting the screw (L) and idle speed (T). To do this, first the screw (L) is tightened until the maximum engine speed is obtained, then it is released by 1/4, and the idle speed is brought back to normal with the screw (T).

After adjusting the work on the "bottom", the thrust and maximum engine speed are adjusted. To do this, slowly tighten the screw (H) and check the speed according to the readings of the electronic tachometer.

it is unacceptable to allow exceeding the maximum engine speed declared by the manufacturer.

An important step is to check the saw in all operating modes after adjusting it, for this you need to let the chainsaw cool down, and then start it according to the cold tool start algorithm. If the saw starts up normally and is idling smoothly, you need to check how it cuts. If in the process of checking deficiencies in the power of the chainsaw are found, then it is necessary to repeat the adjustment of the screw (H) by unscrewing it and checking the thrust in operation.

Adjusting the carburetor of a Chinese chainsaw

The carburetors installed on the Chinese-made saws are made in the same way as the European ones and have the same adjustment screws.

The carburetor of a Chinese chainsaw is adjusted according to the algorithm presented above, and differs in that when initially adjusting the screws (L) and (H), they must be turned out two turns. Further, the carburetors of the Chinese saw are regulated in the same way as the European ones.

Video

The setting of the saw carburetor can be studied in the video below. In this video, the wizard shows how a step-by-step adjustment of a Chinese-made chainsaw is performed without using a tachometer. Carries out after adjustment check in various modes.

Adjusting the carburetor of a chainsaw, although it looks like a fairly simple process, requires a very careful and responsible approach. The article describes the process in sufficient detail, but if you have never adjusted a chainsaw, you should contact a specialist, this will help save time, nerves and money.