Design and adjustment of a chainsaw carburetor

The carburetor is one of the most important components of any modern chainsaw. Its main task is to mix the fuel mixture with air, as well as further delivery of the finished fuel into the cylinder of the gasoline engine. During the operation of the chainsaw its carburetor is constantly working, so over time, this unit begins to need adjustment and washing. To perform these procedures is simple enough if you are very careful and follow the correct procedure.

Almost all carburetors used in chainsaws have the same device. The only difference is the mechanisms with which the Chinese garden tools are equipped with.

As standard, the fuel assembly consists of the following parts:

  • Float chamber. this element is designed to continuously maintain the required amount of fuel. When the node works, the fuel is transferred to the atomizer through the built-in nozzle;
  • The fuel feed tube. it allows fuel to flow into the carburettor chamber in batch quantities. The fuel supply is regulated by the position of the built-in factory flap;
  • atomizer. this part is necessary for injecting fuel into the intake air stream.

The principle of operation of a chainsaw carburetor is quite simple. During operation of the assembly, air is sucked in by the tube and flows through it at a speed that is regulated by the built-in flapper. When the choke is opened, the float in the chamber is actuated. After passing through the nozzle, the air is mixed with fuel and atomized at once. Then the air-enriched, high-quality fuel mixture passes through the intake channel and into the engine cylinder. Explain how a carburetor works in the diagram.

Fuel circulates in the assembly under the influence of pressure. In the float chamber it is close to atmospheric pressure, but in the standard air intake pipe it is more rarefied. Due to the difference in pressure that is formed, the fuel mixture enters the tube. The higher the amount of fuel, the higher the rpm the utility chainsaw engine is capable of generating.

How to stop the gas pedal pump of a chainsaw carburetor

Why can’t you just change the cuff?? I think you can get it from a car carburetor.And the pump will work again.Why else would they make it at the plant in this era of cheapening of goods, could not perform a bunch of operations, if it is without a pump-accelerator. I honestly do not understand why everyone throws it away? Ok, if one of ten has a strong wear in the seating, it is understandable, but why destroy all ?

Good day. Please advise carburetor BP Partner carburetor needle holds the valve injectors checked your way works but the primer does not get gasoline blows gas pedal pump seems not blowing I can not determine the cause of air in the primer.

“Air intake

This is another common reason why chainsaw malfunctions at idle speed. Too much air interferes with the operation of the tool, it does not start or constantly stalls.

  • Fuel hoses. If low-quality fuel is used, small cracks can form on them, they are easy to see upon visual inspection. It is also worth checking the tightness: the hose should sit tight enough.
  • Glands. There are two of these on the crankshaft. Gaskets can wear out in service or simply from time. It is possible to check the tightness with a compressor. This will require closing the inlet on the carburetor and the outlet on the muffler, unscrewing the spark plug and pressurizing air. If you hear a hissing noise or the pressure does not rise, it means that the seals should be replaced.
  • Gaskets. They can be damaged by poor repair, during assembly and disassembly of the tool, during installation.


Another reason for the chainsaw not picking up and stopping is the muffler. There may be soot deposits on the compressor over time. Its appearance is especially promoted by low-quality gasoline and oil, as well as the use of too much oil in the mixture or excessive lubrication. Fouling prevents the exhaust gas from escaping, causing the saw to overheat.

During operation, the chain can simply jam, after which the saw stalls. There may be several reasons:

In all cases, the chainsaw tire stays dry.

The cylinder and piston group (BCG)

This is the most unpleasant and expensive breakdown. The cost of replacing the cylinder/cylinder rod may be half the price of a tool. It’s best to take your saw to a service center and not try to disassemble it yourself.

Troubleshooting a chainsaw carburetor

Removing the carburetor from a chainsaw. Remove the gasoline pump cover with a diaphragm, removing one screw in the center of the cover. Next, turn the carburetor to yourself with the throttle, on the side where there are two holes, you can see a pin in one, here under it and there is a gas pedal pump. Remove the retaining ring from the outside of the pin and disconnect the air damper wire spring. Unscrew the screw in the center of the throttle, remember how the throttle stands (to put it that way later) and remove the throttle. Use your finger to put a pin in the hole (the booster is spring loaded and if you remove the throttle body and leave the hole open, the booster will pop out), then twist the throttle body and take it out. Shake out the gas pedal (piston and spring) from the hole. There is a rubber sleeve (ring) on the piston. its wear and tear is the cause of the chainsaw malfunction. Replace the piston and rubber cuff and spring (they are sold as a repair set). Or you can take out the worn out piston and spring and plug the hole by pushing a rubber stopper in (the chainsaw will be without the booster pump, t.ะต. Will not accelerate in three seconds., in 4 sec., But it will run well because there is no air suction in the carburetor).

Assembly after troubleshooting the chainsaw (after troubleshooting the chainsaw carburetor) is done in the reverse order of disassembly. When assembling the throttle, before tightening the screw, the throttle itself must be properly aligned so it doesn’t jam, and the threads of the screw securing the throttle to the axle should be degreased and smeared with a special thread sealant (available in small tubes, red, liquid) or flattened with pliers, because if this screw gets twisted while running, it goes straight into the cylinder ) and repair or piston replacement can’t be avoided). Here we have looked at troubleshooting this chainsaw malfunction.

Why a chainsaw fires into the carburetor?

The main cause of this malfunction. improperly aligned distance between the ignition elements of the chainsaw. Because of this, the fuel that enters the regular ICE cylinder does not have time to burn completely in it. An explosion-like sound occurs as a result. To effectively solve the problem, you need to set the ignition of the chainsaw, adhering to the instructions in the user manual.

Often this kind of failure in a chainsaw carburetor is the result of a depleted or over-oxygenated fuel mixture entering the cylinder. To fix the failure, you need to adjust the operation of the metal throttle and the regular fuel assembly jets.

Why is oil leaking

Many chainsaw owners are faced with such a problem as oil leakage from under the unit. The most common reason for oil leaks is damage to the oil hose connected to the oil pump. The picture below shows exactly when the end of the hose has burst and is not tightly connected to the pump connection.

But to get to that spot you have to remove the clutch from the shaft. Some chain saw models can have oil leaking from the oil pump connection to the oil tank hose (arrow in the photo).

In order to fix the oil leak, you will need to pull this hose out of its seat. To do this, you can use pliers by pulling on the outside of it. At the end of the hose you will see a rubber plug, which is the reason of oil leakage. This plug should be wiped down well to remove any oil residue, and then its seat should be sealed with something. You can use a car sealant or wicking tape as shown in the following photo.

Next, insert the hose into the hole, put the plug in place and seal it using a flathead screwdriver. At this point the operation to fix the oil leakage can be considered completed.

How to properly adjust the carburetor on a chainsaw?

To independently adjust the carburetor chainsaw brought the desired result, it is necessary to carry out preparatory work. First of all the operator should make sure that the engine is in good condition. To do this, be sure to remove the top cover of the protective plastic housing and carefully examine the engine cylinder for burrs, cracks and other defects. If they were formed, then the surface of the node will need to grind. It is important not to damage the protective coating of the cylinder chrome or nikasilov.

Next, the spark plug should be inspected. In the case of formation of a thick layer of dried carbon deposits on it, the part will need to unscrew and thoroughly clean. To do this, the plug should be heated up and carefully scrape off the dried oil from its tip.

At the end it will be necessary to inspect the parts of the entire fuel system of the chainsaw. Clogging in the pipes, accumulated debris in the fuel and air filters, unstable operation of the diffuser. all this leads to the loss of the necessary engine revolutions. As a result, the operator does not get accurate information about the operation of the engine and cannot set the correct settings. To prevent this, carburetor parts, filters, and tubes need to be flushed. Once they are completely dry, they can be reinstalled in their original place.

In order for the chainsaw to work properly, you need to carefully perform carburetor adjustments in their exact order. If there are any irregularities in the unit, you must do a complete disassembly yourself. In most cases, any parts that have become unusable need to be replaced.

If the carburetor settings are constantly checked, and timely measures are taken to improve its performance, there are no problems with the chainsaw.

, What to do if chain saws won’t start and what kind of nozzles to choose for a chainsaw.

About what to choose a chainsaw. read here.

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