How To Perform Carburetor Adjustment On A Chainsaw?

A chainsaw is a great helper in a private sector, which is indispensable when harvesting firewood, pruning tree branches, as well as in the construction of wooden log cabins for houses, bathhouses and outbuildings. The design of saws allows you to cut and saw cut tree trunks of medium size.

Currently, the market has a large range of chainsaws, among which can be mentioned chainsaws “Partner” of the Swedish concern Husqvarna and Huter chainsaws of the same German company, for their compactness, lightness, performance and reasonable prices.
The ease of maintenance of a “Partner” and “Huter” saws even allows them to be controlled with them for the first time, but a chainsaw is a complex device and requires a caring attitude to itself. In the course of work, various kinds of malfunctions sometimes occur that affect the efficient operation, and the user must be able to cope with them.

How to adjust the carburetor on a chainsaw?

The most common problem encountered when operating a chainsaw is incorrect carburetor operation, resulting in excessive fuel consumption and reduced power, so any user should know how to adjust the carburetor on a chainsaw.
Chainsaw carburetors are also designed as automobile ones, and therefore anyone familiar with the principle of operation of an internal combustion engine can cope with carburetor adjustment and can customize it with their own hands.
The manufacturer of the new saws come with a tuned carburetor, but in the process, the standard setting is broken, and the saw needs to be re-adjusted. The documentation attached to the saw describes how to adjust the carburetor.

Carburetor adjustment needed when the following symptoms:

  • idling the saw is running at high speed;
  • when working he smokes;
  • it does not start well in a cold or warm state;
  • operates at low revs and with reduced pitch.

The device and the principle of the carburetor.

The device and the principle of operation of the carburetor chainsaws are the same as those of the carburetors of internal combustion engines and perform the same function: preparing and feeding the engine an air-fuel mixture to the combustion chamber.

The carburetor consists of the following parts:

  • enclosures;
  • float chamber;
  • needle valve;
  • float;
  • sprayer;
  • fuel jet;
  • mixing chamber;
  • throttle;
  • diffuser.

Atmospheric air, passing through the air filter, enters the air channel of the carburetor, where there is a diffuser, which reduces the diameter of the channel, as a result of which a reduced pressure is created behind the diffuser.
Behind the diffuser, throttle installed, which regulates the flow of air entering the carburetor. Partially blocking or opening the air channel, the damper controls the air flow, thereby regulating the engine speed.
Under the action of reduced air pressure generated behind the diffuser, gasoline from the float chamber through the fuel jet and the sprayer is sucked into the mixing chamber.
In the chamber, the fuel is mixed with air, forming a fuel mixture, and then fed into the combustion chamber. The throttle valve mechanically connects to the fuel jet, which regulates the amount of fuel supplied to the atomizer. Therefore, it simultaneously regulates the flow of air and fuel into the combustion chamber.
The float adjusts the level of fuel in the float chamber, keeping it at the same level. It is connected to the needle valve, blocking the flow of fuel into the float chamber.
When the fuel level drops, the float drops and moves the needle valve, forcing him to tear off the fuel supply hole. When fuel fills the chamber to a normal level, the float moves the needle to the closed position.
Engine speed depends on how much a mixture of fuel and air enters the combustion chamber. The more open the valve, the greater the momentum.

How to set up a carburetor on a chainsaw?

Adjusting the carburetor is to adjust the jet and air damper to obtain the optimal ratio of the amount of air and fuel in the fuel mixture.

If there is a lot of air in the fuel mixture and there is a shortage of fuel, the mixture is lean, so the engine power is reduced.
If a a lot of fuel and lack of air. the mixture is supersaturated, incomplete combustion of the fuel occurs, which leads to smoke, carbon on the piston and in the exhaust pipe and increased fuel consumption.

How to adjust the carburetor?

Consider as an example, the adjustment of the carburetor chainsaws Partner. To adjust, you need to have a slotted screwdriver and the device. tachometer, which allows measuring the engine speed.

Setup is carried out in the following sequence:

  1. setting the carburetor chainsaw at low revs;
  2. adjustment at maximum speed;
  3. fine tuning for idle operation;
  4. check saw operation in all modes.

It is necessary to start after the engine runs and warms up.

Chainsaw adjustment performed using three adjustment screws on its body:

  • screw L. adjustment of fuel delivery at medium and low revs
  • screw H. at high speeds;
  • screw T. at idle.

If the carburetor is completely misaligned and the engine does not want to start, set the L and H setting screws to the standard setting position: first tighten them completely, then unscrew them half a turn.

Start the engine and allow it to warm up, then proceed to adjusting the low speed using the screws L and T.
To do this, unscrew the screw L before reaching the maximum engine speed, and then screw it in turn, and set the idling speed with screw T.
Further, to adjust for maximum speed tighten screw H slowly, achieving the maximum revolutions according to the tachometer readings.
After the adjustment is complete, it is essential to check the operation of the engine in all modes. To do this, you need to drown it and let it cool.
Then start the saw in cold start mode and follow the engine in idle mode. If the gas smoothly increases and decreases, and the chain does not move, the adjustment is correct. Next should be checked during sawing. If there is a loss of power. the adjustment is repeated.

DIY carburetor repair.

The carburetor is easy to disassemble., therefore, repair of the carburetor of the chainsaw can be done by yourself.

For example, if necessary, it is possible to do the following operations with your own hands:

  • replace the gasket under the main chamber lid;
  • wash or replace the fuel filter;
  • replace needle valve and fuel pump diaphragm.

Before disassembling the carburetor, it is necessary to clean the dirt from the surface of the body, as it can get inside the carburetor and clog the holes of the needle valves and the nozzle.
Next, you should undock the mountings of the control air and throttle, dismantle the air filter and remove the cover of the main chamber, unscrewing the screws. After that, you can begin to replace the mentioned parts.

Very often, the reason for not starting the saw can be defects in the ignition system, in particular, candles due to the following reasons:

  • nagar on a candle. indicates poor quality oil or improper adjustment of the carburetor;
  • filling the spark plug with fuel is an incorrect carburetor adjustment.

To check the condition of the candle, unscrew it with a special key from the cylinder head.

Nagar on a candle removed with a needle or sewing, and, if necessary, with a sandpaper, then put it in place and try to start the engine.
We rub the flooded candle with a cloth, dry it, put it in place and try to start the saw.
In some cases, the engine smokes and stalls at high speeds. The reason may be the clogging of the muffler with exhaust products, so you need to remove the muffler, wash the soot with gasoline, wipe, dry and put it in place again. While the muffler is not in place, the exhaust port should be closed with a cloth to prevent dirt.


Setting the saw carburetor and repairing it’s minor can be done without experience, but you need to follow the algorithm prescribed in the accompanying documentation to do it correctly. However, you should not overestimate your strength, because sometimes it is cheaper to pay a specialist for quality service than to eliminate the consequences of your unprofessional repair.