How to clean a Chinese chainsaw carburetor

Cleaning the carburetor of the Chinese chainsaw

Dust, small rocks, and other debris often ends up in the fuel tank when you operate the machine. The fuel filter is responsible for catching them, but if you use the chainsaw a lot, the filter will gradually get dirty. As a result, it loses the ability to perform its function.

This element can also be subjected to such a negative process as oxidation. deposition of oxide on the inner walls of the fuel tank. This happens if the chainsaw has not been operated for a long time and there is fuel left in the tank. After that, the beginning of operation leads to sediment in the carburetor, clogging it.

carburetor structure and principle of operation

Let’s see how a chainsaw carburetor works. This instrument consists of:

  • housing;
  • The diffuser, which is located at the entrance of the device;
  • jets;
  • the valves that regulate the mixture flow;
  • a special atomizer;
  • float chamber.

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

  • When you turn on the motor, the air damper.
  • Air moves forward and mixes with the fuel in the diffuser, where the passage narrows.
  • The air goes through the nozzles, then is cleaned by the filter and comes through the damper, located at the inlet of the diffuser.
  • A special flap, which is located behind the diffuser, distributes the mixture and it enters the combustion chamber.

The device is arranged in such a way that the volume of fuel that passes through the nozzles is regulated by the bolts of the chainsaw. Volume of fuel in the combustion chamber depends on the sharp cone valve. This valve is controlled by a diaphragm that controls the flow of mixture into the chamber. How these parts work depends on the rotation of the engine. The mixture is cleaned with a filter.

How a chainsaw carburetor works

Most modern chainsaws have almost identical carburetors. they are virtually identical to one another and work on a similar principle. The only difference between the chambers of different manufacturers is in the material from which they are made. In expensive American, Swedish and German chainsaws the chambers are made of reliable alloys that are coated with protective coatings. Cheap Chinese and Korean chainsaws are equipped with nodes made of cheap materials. Each carburetor consists of the following components:

  • aluminum monocoque body with one-piece construction. Inside the housing there is an inlet fitting, the main screw, the impulse channel, a bolt for adjusting the engine when idling;
  • Throttle valve. it is responsible for adjusting the amount of air required to enrich the fuel mixture;
  • The diffuser is located near the inlet of the camera;
  • atomizer. designed to supply fuel mixture directly into the carburetor chamber;
  • Float chamber. there is a float in the chamber which activates in case of insufficient quantity of fuel;
  • nozzles. they are valves that are responsible for adjusting the amount of fuel.

This chainsaw carburetor circuit is as simple and effective as possible. In some models of garden tools it can be supplemented with additional spigots, glands or filters.

The principle of operation of a chainsaw carburetor is quite simple. At the moment the engine is started, the air damper at the bottom of the housing opens. In the float and air chambers, a negative pressure is created as a result of the piston movement. As a result, the standard diffuser is triggered and begins to suck in air.

Subsequently, the fuel in the air chamber begins to mix with the air. The finished air-fuel mixture then passes through the intake valves, from where it is sent to the combustion chamber of the saw’s engine.

The carburetor of any newest chainsaw is an integral part of the engine, which continuously regulates the amount of air needed to continuously mix with fuel, and feeds the ready mixture into the cylinder of the ICE.

In most modern chainsaws, the integrated carburetors initially have a similar design and almost identical operating principle. There are some differences only in the fuel units of Chinese models.

The main elements of all chainsaw carburetors include:

  • Float chamber. a small compartment, the main task of which is to maintain the optimal amount of fuel filled;
  • atomizer. an important mechanism that is initially responsible for fuel injection into the intake air stream;
  • diffuser. located near the regular inlet, through which the air enters the engine compartment of the chainsaw. The main function of the diffuser is to forcibly accelerate the intake of air masses;
  • tube. required for supplying air in small volumes. portions whose size depends on the needs of the fuel system.

The principle of operation of the chainsaw carburetor is also quite simple. When the chainsaw is started, the engine throttle actuates, which, when open, allows air to flow through the factory rubber tube. With the gradual opening of the regular flap and the tube connected to it, the float, located in the chamber with the filled fuel, is activated.

When atomizing fuel the pressure inside the float chamber is almost identical to the atmospheric pressure. At the same time, the pressure in the factory air tube is rarefied. Due to the difference in these values, air is continuously sucked by the tube. At higher engine speeds, it needs more fuel.

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A chainsaw is also needed in construction, gardening and landscaping. its presence greatly simplifies a number of woodworking tasks. The main unit of this tool is the engine, the operation of which depends largely on the condition and settings of the carburetor. This is where the fuel mixture is prepared.

So if the machine won’t start, stops, or doesn’t deliver the power you expect, it is probably because the carburetor is not working properly. Fortunately, in many cases you can fix it yourself.

Only for this purpose it is necessary to know and understand the construction and principle of work of the given unit and, certainly, of the chainsaw itself.

STIHL MS 181 C BE chainsaw carburetor

Chainsaw carburetors can be different in design. However, their basic elements and principle of operation remain approximately the same.

It is an aerodynamic tube with an air slide across which the intensity of the air supply is regulated.

This part is where the tube of the basis is narrowed. here the speed of the air flow increases, t.е. the air is always supplied to the carburetor under some pressure.

In this area, the fuel is in contact with the air flow. Fuel enters the atomizer from the float chamber through the nozzle (metering unit).

It is a container that holds the fuel mixture in a stable state.

Construction diagram of a chainsaw carburetor

The chainsaw carburetor works according to the following principle:

  • When the engine is started, the main flap opens and a stream of air is blown into the air duct at a certain speed;
  • the airflow rate and the float level in the chamber are controlled by the position of the choke, namely by the pressure difference in the float chamber and the air duct;
  • fuel from the float chamber is sucked into the nozzle, and from there into the diffuser;
  • passing through the diffuser, the air captures the fuel going in;
  • the resulting mixture is fed into the cylinder cavities through the intake ducts.

the pressure in the float chamber is approximately equal to atmospheric pressure, but in the air ducts of the carburetor when starting the chainsaw engine there is a vacuum. the opening of the butterfly valve increases the intensity of the air supply. the result is that more fuel enters the carburettor and the engine speed increases.

Chainsaw carburetor design

The carburetor of any newest chainsaw is an integral part of the engine, which continuously regulates the amount of air required for constant mixing with the fuel, and feeds the ready mixture into the engine cylinder.

In most modern chainsaws the built-in carburetors initially have a similar structure and almost the same principle of operation. Only the fuel assemblies of Chinese models have certain differences.

The main elements of the carburetors of all chainsaws include:

  • Float chamber. a small compartment whose main task is to maintain the optimal amount of fuel filled;
  • atomizer. an important mechanism, which is initially responsible for fuel injection into the intake air flow;
  • diffuser. is located next to the regular inlet opening through which the air enters the engine compartment of a chainsaw. The main function of the diffuser is to force the intake of air masses;
  • tube. is required to supply air in small volumes. portions, the size of which depends on the needs of the fuel system.

The principle of a chainsaw carburetor is also quite simple. When the chainsaw is running, the engine throttle is actuated, which lets air in through the factory rubber tube when it is open. The float located in the filled fuel chamber is activated with the gradual opening of the standard fuel valve and the tube connected to it. Continuously passing through the standard diffuser, the air is intensively mixed with the fuel. The ready-to-use air-fuel mixture is then sprayed into the working cylinder of the regular engine through the factory intake.

When atomizing fuel, the pressure inside the chainsaw’s float chamber is almost identical to the atmospheric pressure. At the same time the pressure in the factory air tube is rarefied. Because of this difference, air is continuously sucked in by the suction tube. As the engine rpm increases, it needs more fuel. Accordingly, the tube has to suck in more air. So it is mainly the carburettor that determines whether or not the engine can rev up quickly enough to cut big wood.

How to adjust

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

Before setting up, read the instruction manual of the saw. When making adjustments, the rules should be followed:

  • Place the tool on the workbench so that it is in a stable position.
  • The chain of the device should be directed away from yourself.
  • Between the tool and other objects in the room should be at least 2 m.

Important is the information on how to tune when the design is disturbed. Turn the carburetor on and wait 10 minutes. Adjustment begins with finding the location of the L screw, at which the idle speeds will be high. A spanner is needed for adjusting the bolts. Gradually turn the bolt first to one side, then to the other, until the right position is taken. Then turn the screw 1/8-1/4 turns counterclockwise. Then correct the slack with the screw S (or T, LA).

КАК ПРОВЕРИТЬ РАБОТУ ИГЛЫ КАРБЮРАТОРА Маленькие хитрости бензопилы.Little tricks Chinese chainsaw

If the chain does not move after tightening the needle bolt L, gradually turn the screw S clockwise until the chain starts moving. Then adjust S by 1/8-1/4 turn back. If the chain moves, turn the screw S counterclockwise until it turns. Further we twist S by 1/8-1/4 turn in the same direction.

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the internal combustion engine should function evenly. Also check how it accelerates. If the gas pedal is pressed, the revolutions should increase to the maximum. This means the motor is spinning well.

At the end, test the operation of the device at idle speed. When the adjustment is done correctly, the design should not work like this:

If these requirements are not met, then the idle speed has to be readjusted. To do this, tighten the screw S as described earlier. If this does not help, you need to repeat the adjustment procedure from the beginning.

This is how you do a manual tune-up. Precise adjustment is done with a tachometer instrument. All actions are the same, only the screws are turned, based on the tachometer data. With this device, the carburetor can be adjusted faster.

How to flush a chainsaw carburetor?

To think about cleaning the fuel node of the gasoline tool should be in such cases:

  • if the engine is difficult to start;
  • When the engine is unstable at short idle speed;
  • In the case of a sag when the regular throttle trigger is pressed smoothly;
  • when fuel consumption increases significantly.

Most often, to flush the built-in carburetor of a chainsaw, liquids are used, which are available in almost every garage:

Modern gardeners who use powerful professional saws use more efficient and gentle means:

  • Mannol Vergaser Reiniger, a cleaner commercially available as an aerosol. It quickly and easily breaks down even the oldest formations of tar, carbon deposits, oily residue, and other types of contaminants;
  • Hi-Gear. this cleaner stands out for its high dissolving properties. It can remove old dried stains, oily crusts and the first signs of rust without harming parts of the fuel system;
  • Jet 100 Ultra is a high-tech spray designed for quick carburetor cleaning on chain saws. Shows a high rate of dissolving the oldest oil stains.

Cleaning the carburetor on a chainsaw is performed in this sequence:

  • First you need to clean the outside of the saw’s engine, as well as dismantle and thoroughly wash the factory air filter housing;
  • Then you can proceed to the disassembly of the gasoline tool. To do this, you need to remove the filter housing, as well as unscrew the fasteners that hold the carburetor together with the engine;
  • You will then need to carefully disconnect the pull and throttle cables from the carburetor. The springs present in the design must be removed so as not to stretch them;
  • After that it is necessary to carefully pull the fuel hoses from the factory connections of the fuel assembly;
  • To clean the carburetor on the chainsaw, you need to remove it from the branded fastening studs. At the same time it is important to maintain the integrity of the gasket installed between the engine cylinder and the fuel assembly;
  • The next step is to clean the outer walls of the carburetor. To do this, they can be treated with a liquid cleaner or gasoline. At the same time, you need to try to ensure that the dust and debris do not get inside the node or cylinder of the motor;
  • Next you need to unscrew the screws fixing the carburetor diaphragm, remove its cover and wash the inner cavity with an aerosol cleaner;
  • After that it is necessary to dismantle the fuel pre-fine filter, as well as to disassemble the part of the unit, to which the fuel is supplied. All internal parts of the carburetor should be thoroughly washed with an aerosol cleaner. If the first cleaning did not yield results, the flushing should be repeated.

To clean the assembly from heavy dirt, it is best to use a product that comes on sale in pressurized cylinders. The cleaner comes with a dispenser and a long, thin tube that allows you to spray in all the hard-to-reach places.

The most powerful chainsaw in the world: Top 4

clean, chinese, chainsaw, carburetor

It must be remembered that cleaning the carburetor on a chainsaw is performed with the use of flammable chemicals. Work with them must be in a special protective mask and only in well-ventilated rooms.

To clean the carburetor on the chainsaw, the assembly will need to be partially disassembled. The throttle, adjustment screws, body and other parts of the carburetor will need to be washed with the product from the canister and put aside until completely dry. Once all the elements are dry, the assembly can be assembled and put back on the chainsaw.

When adjustment is needed

As mentioned before, the new chainsaw already has standard fuel settings. But for a proper running-in is recommended to limit the maximum engine speed, and this is done with the adjustment screws located on the carburetor body. Also after the running-in period it will be necessary to make again a more accurate adjustment of the fuel mixture.

In addition, to adjust the carburetor will have to in the following cases:

  • Due to the strong vibration the factory settings are knocked down;
  • The engine starts badly and immediately stops;
  • The engine starts, but the revolutions do not develop, and it stalls;
  • the piston group is worn out. in this case, the adjustment of the carburetor of a chainsaw is possible as a temporary measure;
  • the engine does not function at idle speed;
  • increased gasoline consumption, so that the unit produces a lot of smoke, the muffler and spark plug dirt is soiled by carbon deposits, engine power is reduced.

Adjusting the carburetor of a Chinese chainsaw with their own hands

Not all carburetors on a Chinese chainsaw have an adjustable throttle. Today there are many chainsaw models of the domestic class, including European brands, on the carburetors of which there are simply no adjusting screws. Or there is only one screw for idle speed adjustment.

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Such carburetors require adjustment only when the chainsaw at idle rpm makes too infrequent exhausts (rpm) and occasionally stalls. Below the text will consider the algorithm for adjusting the idle speed carburetor on the Chinese chainsaw.

Needed tools

Adjustment requires a screwdriver that fits the slits of the adjusting screws. On different carburettors they are flat, Phillips, with internal or external hexagon, star, etc.п.

When adjusting the electronic tachometer will help. If it is not available, the adjustment is carried out by ear, and by assessing the real operation of the engine.

clean, chinese, chainsaw, carburetor

carburetor adjustment algorithm

Check to see if the adjustment is necessary beforehand. All Chinese carburetors, on every chainsaw have a factory setting, which is knocked down very rarely. Adjustment may require a new carburetor or in rare cases an old one.

The cause of engine deterioration with signs similar to poor fuel mixture, in most cases are:

If that is not the problem, then try to adjust the carburetor.

The engine must be warm. Engine performs differently when cold and warmed up to operating temperature. Therefore, adjustment will be incorrect when the engine is cold.

  • Allows access to the adjustment screws. On some chainsaws it is sufficient to remove the cover and the air cleaner. On others, you have to remove part of the housing. Some have screwdriver holes in the housing.
  • On the carburetor or near the holes there are markings of screws. T (or LA) L and H. T (or LA) is for idle speed adjustment. Always located away from the L and H screws, which are next to each other.
  • If the chainsaw stalls when throttle is applied. the engine does not have enough fuel to reach revolutions. Adjust the fuel rate with the screw H (main screw). Turn it in 1/4 turn and put throttle on. If the engine starts to run better, crank it out another 1/4 turn. (If worse, turn it in 1/4 turn in the opposite direction.).
  • if engine starts to run better at idle, it means there is too much fuel, turn back the H screw.
  • Check peak rpm by ear or tachometer. Maximum rpm for each chainsaw is given in the instruction manual. (10 000. 12 500 rpm). In practice, 10,000. 11,000 rpm at full throttle is normal.
  • After increasing the amount of fuel with the H screw, correct the quality of the fuel mixture with the L screw. It increases and decreases the amount of air in the mixture. If there is not enough air the fuel will not burn out, and as a result the engine smokes, does not develop capacity and spends unnecessary fuel. The L screw also affects the engine running at low and medium rpm.
  • After adjusting the H screw, the L screw is unscrewed by 1/4 turn. If there is smoke in the exhaust and the engine goes from low rpm to medium and high with dips, tighten the L screw more.
  • Stop adjusting the L screw when the engine runs smoothly from low rpm to high rpm and there is no smoke.

After adjusting the two main screws, most often you need to adjust the idle speed with the third screw.

clean, chinese, chainsaw, carburetor

The locations of the adjusting screws are marked in red. To access them, it is enough to use a screwdriver. There is no need to disassemble anything.

Idle stroke setting

Idle speed adjustment sequence:

  • Start the engine and warm it up for 5-7 minutes.
  • turn the screw more until the chain starts to scroll.
  • Then screw back in 1/4 turn.

If there is an electronic tachometer, its indications should be used for adjustment. Most chain saws should reach an idle speed of 2500 rpm.

Nuances that arise in the process

The L screw must not be turned too far out relative to the H screw. This leads to a leaner air-fuel mixture (less gasoline. more air). With this mixture, the piston is dry during operation, gets very hot and can fail.

The factory-supplied Chinese carburetor that comes with the chainsaw is tuned at the stands to suit the characteristics of each chainsaw. Therefore, any change in the position of the screws during adjustment should be memorized or written down so that you can return to the factory settings if the engine fails to start.

New carburetors on Chinese chainsaws, sold separately, are adjusted in the factories by the standard number of revolutions or arbitrarily. That’s why they may need adjustment after being installed on the chainsaw.

Reassembly after repairing the chainsaw malfunction (after removing the carburetor chain saw malfunction) is done in the reverse order of disassembly. When reassembling the choke, before screwing in the choke should be properly positioned so that it does not stick, and screw the choke screw on the axle, degrease and spread with a special thread sealant (sold in small tubes, red. fluid) or pliers, because if this bolt comes out during operation, it goes straight into the cylinder), and the repair or replacement of the piston cannot be avoided). So we looked at troubleshooting this chainsaw malfunction.

chainsaw chinese carburator cleaning


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