How to adjust the carburettor on a STIHL 28 chain saw

About the carburetor

A carburetor is used to mix the fuel-air mixture in a pre-set proportions. If the exact doses are not respected, engine performance is compromised. When during mixing the components a large amount of air is supplied, but not enough fuel, such a mixture is considered “poor”.

It should not be allowed to oversaturate either, as a large amount of fuel compared to air can also cause malfunction or engine wear. Carburetor adjustments are needed not only before initial use, but also when any abnormalities in its operation are detected. Before you start working with the chainsaw, don’t forget to run it in.

The carburetor design contains a standard set of elements, but may vary slightly depending on the manufacturer. Components:

  • The base. This is a special tube, which visually resembles an aerodynamic design. The air passes through it. In a transverse direction in the middle of the pipe there is a damper. Its position can be adjusted. The more it is extended into the aisle, the less air is delivered to the engine.
  • Diffuser. This is the narrowed part of the tube. It is used to increase the rate of air flow exactly in the segment where the fuel comes out.
  • Fuel lines. The fuel-air mix is in the float chamber, then travels to the nozzle where it exits to the atomizer.
  • Float chamber. Is a separate structural element, resembling the shape of a tank. Designed to keep the optimum level of fuel fluid at all times before it enters the channel where the air enters.

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Or look at foreign chainsaw makers, like STIHL.

The main telltale signs that the carburetor needs adjustment:

  • the saw consumes a lot of fuel,
  • exhaust emissions,
  • Muffler, filter and fuel line become dirty quickly,
  • Engine won’t start for a long time,
  • chain saw frequently stalls.

These problems are not necessarily carburetor-related. So before you start, check the other elements of the chain saw.

  • Fuel filter and hose. Remove dirt from the filter, make sure the hose itself is intact.
  • Air filter. Clean off the dirt, make sure the filter is not torn.
  • The spark plug gives a spark without interruption, if this does not happen. replace the spark plug.
  • Engine crankcase is sealed. Air intake causes the RPM to increase and you can’t adjust the throttle.

After checking and correcting these problems if the cutter keeps faltering, adjust the carburetor.

Adjusting the carburetor on a STIHL 290 chain saw

Starting the STIHL chainsaw review, we have a few suggestions for the famous STIHL brand, which has guaranteed high quality and reliability for almost a century. The company was founded in 1921, the first petrol saw appeared in 8 years and weighed 48 kg and required two operators to operate it.

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Engineers of the company have continued their developments aimed at reducing and facilitating the chainsaw, today we see that their efforts have been successful. A modern STIHL gas saw weighs about 6-7 kg and is operated by one person.

It is also equipped with many useful features that make the operator’s work safer and more comfortable. Calm saws are by far the most expensive and slowest on the international market.

To avoid fakes

To begin with, a chainsaw buyer must pay the price of the product, look at various websites to see how much the tool costs. Note right off the bat that STIHL originals can’t be cheap! Counterfeit equipment will be much cheaper, luring the inexperienced buyer with its apparent affordability.

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We suggest you watch a video on how to choose a chainsaw and how real and fake chainsaws differ:

Note that the Chinese STIHL chainsaw has the following differences from the original:

Operating and Service Instructions

STIHL 250-ms model operating instructions:

  • After assembly, the tool needs a running-in period before starting regular work, the running-in period takes about 5-7 hours, during which time the intensity of the chainsaw should be medium;
  • after the running-in period, the chainsaw can be switched to normal mode, avoiding overheating of the engine and the bar;
  • It is advisable to use the saw only in protective gear;
  • it is forbidden to leave the tool running.


  • difficult repairs or elimination of serious faults, while the chainsaw is under warranty, must be performed by a service center;
  • disassembly of the saw is prohibited as long as the warranty is valid;
  • independent adjustment of the carburetor is carried out after the end of the warranty, in the previous period. by the service specialists;
  • The general machine setup before use is described in detail in the instruction manual;
  • regularly. inspection for integrity, cleaning the air filter from sawdust, lubricating the tire and chain, once a month check the condition of the spark plug, the ignition system, and prepare a fresh fuel mixture, once a year the carburetor is adjusted.

Adjust the carburetor 180. basic steps

If a situation arises when the tool needs a repair for greater performance and fuel economy, the performed adjustment of the carburetor with all related operations will be a must. And so, performing carburetor adjustments on the saw’s 80 carburetor system is a must:

adjust, carburettor, stihl, chain
  • Clean the fuel tank and air filters, which will ensure better action.
  • Determine the H, L and S screws on the carburetor.
  • Using the marked screws make basic adjustments to the fuel mixer STIHL 180 with the engine turned off: using the manual to set the exact angles of the screws H and L, which regulate the gasoline/air ratio, where the screw H is the maximum speed screw for the jets; L is the minimum speed screw; S is the idle speed screw. setting the basic values, slowly turn the H and L clockwise, after the stop to return to the position 2 revolutions back.
  • Start the engine and perform the final hand adjustment of the STIHL carburetor. Find the highest idle speed by turning the L screw in different directions. Once the maximum is found, return the screw to 1/4 of a clock’s stroke. If the chain is running, turn the idle speed screw back until it has come to a complete stop.
  • Performs a technical check and adjusts the acceleration and maximum RPM.
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A correctly performed carburettor adjustment 180 will allow you to get the maximum rotation of the chainsaw with the best productivity, when the quality of work and fuel consumption will find the best ratio. In the company “grass mower for grass Motors” you can get detailed information about self-adjustment chain saw and other benzoinstrumentov treatment of wood and vegetation, for which the site of the company you can choose and order spare parts for brushcutter of any manufacturer, lawn mower, gasoline and electric saws.

Adjusting a chainsaw carburetor with your hands

Adjusting the chainsaw carburetor allows the tool to operate efficiently at full throttle while saving fuel. Adjustment should be performed with a clean fuel and air filter. For more carburetors adjustment is made with three screws: for maximum and minimum revolutions and idle speed adjustment.

the H and L screws are used to adjust the petrol/air mixture ratio determined by the throttle opening on the carburettor. Unscrewing the screws enriches the mixture and lowers the engine rpm, tightening the screws reduces the mixture and therefore the engine rpm increases.

The designation H refers to the maximum RPM screw that controls the main nozzle, L. to the minimum RPM screw that controls the idle speed nozzle. The S screw is used to precisely adjust the idle speed. Sometimes, to make adjustment easier, the number of available carburetor adjustment screws are reduced.

Setting the carburetor of a chainsaw is divided into two steps basic (factory settings), performed with the engine turned off. and final, performed on a running warm engine. For the exact values of the rotation angles please refer to the instruction manual of your chain saw. Failure to comply with the manufacturer’s instructions may cause damage to the engine.

The maximum H and minimum L rpm setting screws should be turned slowly clockwise as far as they will go and then turned back two turns

Find the highest idle speed, to do this slowly turn the L screw in different directions. After finding the position of highest engine revolutions turn the L screw 1/4 turn counter-clockwise. If the chain is idling, turn the T or (S) screw clockwise until it stops.

Checking and Adjusting the Maximum RPM.

Changing the maximum rpm is done with the H. If it is turned in (clockwise rotation) the rpm increases, if it is turned out. decreases. Chainsaw engines have the maximum rpm at 11500 rpm. to 15000 rpm. The higher speed is not provided by the ignition and it becomes dangerous for the engine. Limit revolutions can be determined by the ignition interruption. If this occurs, turn the screw H slightly anticlockwise.

If the operation of the engine is not checked for acceleration and maximum rpm then the chainsaw adjustment cannot be considered complete.

Correct Way To Adjust Or Tune The Carburetor On A Chainsaw

When smoothly pressing the gas trigger, the engine should confidently and quickly gain revolutions from idle to maximum (from 2800 rpm to 15000 rpm).to 11500-15000 rpm depending on the machine). If the revs are slow and lag behind, the L screw should be turned slowly anticlockwise, but not more than 1/8 of a turn.

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After adjusting the acceleration and maximum RPM, the saw should be checked again at idle speed. the engine must run steadily, the chain must not move. Chain saw adjustment must be repeated if this condition is not met, but except for the basic adjustment step.

Adjusting a chainsaw carburetor

Chainsaws are very popular gardening tools. They have gained great popularity among gardeners and those who take care of the territory on yard plots. Construction or renovation work is also not without chainsaws. Chainsaws are even more important in the wood-cutting profession.

Every chainsaw requires proper care, service, and adjustment before operating. Excessive strain on the tool can shorten its service life and cause the tool to break down.

Today we’re going to talk about that part of the chainsaw’s mechanism that has the job of preparing the fuel before it enters the engine cylinder. This is the function of a chainsaw carburetor. This is what will determine how well the chainsaw works and how much fuel it wastes when it works. If you see that your gasoline chainsaw is not running smoothly, you may need to adjust the carburetor.

How the carburetor works

Regardless of which chainsaw manufacturer you use, the carburetor operating procedures and principles remain the same. This device consists of several basic elements:

Under atmospheric pressure, the air, after passing through the preliminary purification, enters the narrow part of the tube, where its flow is regulated by means of a flap. Here too, the air is discharged and the resulting vacuum draws the fuel from the fuel line. To adjust the fuel flow, you use a special needle connected to the chamber of the nipple. The quality of the fuel mixture is regulated with the help of a choke. when the air is opened more fuel starts to flow into the carburettor and the power of the engine increases.

To avoid problems with the operation of the tool, it is necessary to periodically adjust the chainsaw. When too much air enters the mixture, it becomes depleted, and the engine power decreases. A lack of air also has a negative effect on the unit’s performance because fuel consumption increases. At the same time, it does not burn completely, which leads to the appearance of soot on the walls of the cylinders. It is quite obvious that the question of how to adjust the carburetor on a chainsaw is asked by many owners of this tool.

First, however, it’s worth noting the signs of a quality powertrain:

  • RPMs are quick to pick up.
  • The sound when the engine is running is similar to a four-stroke.
  • There is no cranking of the circuit at idle.
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