Stihl 250 Carburetor Adjustment

Operational capabilities

The Stihl 250 saw is characterized by its versatility, economical use, stability of operating parameters throughout the overhaul and operating life.

  • The tool is equally successful in transverse, longitudinal and diagonal cuts of all types of wood, the length of the bar allows you to work with material up to 35 cm in diameter.
  • In the production of this model, modern materials and new technologies for their processing are involved. The saw assembly is carried out at a high technological level, which reduces the likelihood of failure or malfunction to a minimum.
  • Fine tuning of the fuel equipment allows you to use the traction and economical resources of the standard engine with maximum efficiency.
  • The instruction manual attached to the tool includes information on preparing the saw for work, maintenance features, and finding and self-elimination of possible malfunctions.
  • The repair assortment is represented by a fairly wide choice that allows you to restore the performance of a worn out unit or system with minimal time.

Range of application

The saw is positioned by the manufacturer as a versatile, easy to maintain and durable tool.

The scope of its application extends to a wide range of chores related to:

  • With sawing fuel wood;
  • Caring for ornamental and fruit trees;
  • Construction of wooden structures and structures;
  • Decoration of original architectural and landscape design.

Stihl 250 Carburetor Adjustment


A feature of the tool is the combination of optimal power with a small-sized layout and comfortable working conditions. The design of the saw features excellent balance, the shape of the body and handles that are comfortable for a secure grip. The use of modern materials has reduced the weight of the tool to 4.6 kg.

The Stihl MC-250 chainsaw is powered by an air-cooled carburetor ICE with a working volume of 45.4 cm3. Compact, easy-to-maintain and economical in terms of fuel consumption, the power unit develops 3.1 hp at operating speed. The fuel is a gasoline-oil mixture that enters the carburetor float chamber from a 470 ml tank built into the body.

The characteristics of the engine provide for a large margin of torque and overhaul life, reducing the noise background to 101 dB. Comfortable operation is ensured by the effective operation of the vibration damper.

ModelStihl MS 250
Manufacturing (assembly)Germany
The birthplace of the brandGermany
Saw classSemi-professional
Power, h.P. (kw)3.1 (2.3)
Engine volume, cm345.4
Chain pitch, inches3/8
Chain thickness, mm1.3
Fuel tank volume, l0.47
Oil tank volume, l0.2
Tire length, cm (inches)30-40 (12-16)
Noise level, dB (A)101
Warranty, years1
Weight, kg4.6
Instructions Download
Detailing Download

Disadvantages and malfunctions

The risks of failures and malfunctions are eliminated by timely maintenance and competent use.

In Moscow and adjacent regions, the cost of the new Stihl chainsaw model MC-250 has stabilized in the range of 17,200-18,000 rubles. According to experts, this indicator fully corresponds to the level of quality, productivity and durability of the tool.

The demand for used analogs is moderate, the owners are more interested in offers for the sale of branded spare parts. In particular, many owners of budget Chinese-made models prefer to use calm tires and chains.

Carburetor adjustment

The fuel system of the new saw provides the engine with maximum traction parameters and economical fuel consumption in all modes. The need to additionally adjust the carburetor arises when there are sharp changes in air temperature, the use of fuel with a different octane number, with pronounced instability of revolutions.

If the engine does not start, you should first make sure that there is fuel in the carburetor and that the spark plug is working properly. The engine stalls when the gas is pressed. The reason is most likely a decrease in the performance of the main jet.

The fuel system is adjusted with the engine running after the cylinder has warmed up to operating temperature. By rotating the screws of quantity and quality, the power unit is brought to the optimal operating mode.

Differences between the original and the Chinese version

The popular base model became the basis for the production of the substandard counterpart. Chinese Stihl, with more or less success, copies the appearance and structure of a proprietary instrument, but is significantly inferior in technical and operational characteristics.

Most of the counterfeits are presented in the assortment of small trade organizations. In order to avoid possible risks, it is better to buy the original from certified dealerships and sales representatives.

The differences between the Chinese counterfeit and the branded instrument are noticeable even upon a superficial examination. First of all, these are:

  • Low quality and rough texture of the body plastic;
  • Custom logos and stickers;
  • Lack of serial numbers and equipment of engines with simplified non-compensated carburetors;
  • The presence of spark plugs with calm symbols, which the company does not manufacture.

A significant part of the repair range in the domestic market is represented by low-quality and short-lived spare parts and consumables made in China. Practice shows that the service life of these products is less than half the resource of branded counterparts.

Stihl chainsaw carburetor setting ms 660

Stihl does not use ready-made components from third parties to assemble their chainsaws. Therefore, the original Stihl MS 660 chainsaws are equipped with carburetors manufactured by this company. Chinese chainsaws can have carburetors manufactured by Walbro, Rezer, Kimoto, Cingcong, as well as other unknown manufacturers.

  1. What carburetor is installed on the Stihl MS 660 chainsaw
  2. The device and principle of operation of the Stihl MS 660 chainsaw carburetor
  3. Do-it-yourself Stihl MS 660 chainsaw carburetor adjustment
  4. What is needed to adjust
  5. Standard or basic adjustment
  6. Current setting
  7. Idle speed adjustment
  8. Features and differences of carburetor adjustment on a Chinese chainsaw
  9. What is the difference between the Stihl MS 660 carburetor and the Stihl MS 650
  10. Similar posts
  11. How to Adjust the Chainsaw Carburetor. Chainsaw Maintenance. Dismantling the carburetor chainsaw Chinese Stihl 660 does not adjust the carburetor on. Part 11
  12. Chinese Stihl IGNITION and Carburetor Tuning.
  13. Similar posts
  14. Symptoms of malfunctions and breakdowns in which carburetor adjustment is required.
  15. Purpose, design and principle of operation of the carburetor.
  16. Husqvarna Saw Carburetor Adjustment.
  17. Chainsaws Partner and Stihl, their adjustments.
  18. Tuning the carburetor of a Chinese chainsaw

What carburetor is installed on the Stihl MS 660 chainsaw

The carburetor of the Stihl MS 660 chainsaw is of a membrane type, which allows it to work even in an inverted position. The company has more than half a century of chainsaw production, so each unit is perfect enough.

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Non-original products from other manufacturers most often have an identical design.

Chainsaw Stihl MS 660. One of the most powerful in the world (7.1 HP), professional grade.

Therefore, the carburetor on it is distinguished by increased throughput, sufficient for such an engine size, and reliability.

Husqvarna Saw Carburetor Adjustment.

For the break-in mode, so that the parts receive sufficient lubrication, the carburetor setting of the Husqvarna chainsaw is made so that the maximum speed is 600-700 rpm. Below working. If it is not possible to set the operating maximum frequency using the tachometer, you should not change the presets with the H screw. It is forbidden to exceed the value of the maximum number of revolutions by the manufacturer. If, after completing the adjustment, the saw chain moves when the engine is idling, turn the screw T counterclockwise to bring it to a complete stop.

For accurate adjustment, the saw must be warmed up for at least 10 minutes, set on a flat surface. The tire should point away from the person making the tune. At the initial stage, the highest idle frequency should be found. To do this, screw L is smoothly turned first from left to right, then vice versa. When the maximum revolutions are found empirically, screw L should be unscrewed counterclockwise by a value from 1/8 to a quarter of a full revolution.

The idle speed is adjusted by the nozzle marked with the letter T. It must be turned from left to right until the chain starts to move. Then push slowly in the opposite direction until the chain stops rotating. Screw H is considered to be installed correctly if the noise of the saw at full throttle without load remains small. If the exhaust is too smoky and the saw makes a lot of noise, the mixture is too rich. Turn the H jet clockwise until the correct sound is set. How to properly tune the carburetor can be seen below.

Features and differences of carburetor adjustment on a Chinese chainsaw

The carburetors on Chinese chainsaws are mostly copied from the original Stihl design. Therefore, the adjustment algorithm on the original and Chinese versions is almost identical.

Non-original products are worse in that they use low quality alloys, short-lived plastic parts (membrane and gaskets), the dimensions of the calibrated holes are not exactly maintained, etc.

For informational purposes, we recommend that you look at interesting things about the Chinese chainsaw Stihl МС 660. The chainsaw is completely disassembled, the condition of the components, including the carburetor, is assessed. Also, the author disassembles the carburetor and shows by example how to clean it from dirt.

How to Adjust the Chainsaw Carburetor. Maintenance chainsaws. Dismantling the carburetor chainsaw Chinese Stihl 660 does not adjust the carburetor on. Part 11

In this we will answer the question of how to set up or adjust the carburetor of the chainsaw do it yourself

Current setting

Experienced operators in the process of work may notice that the internal combustion engine of the chainsaw has begun to work worse. Sometimes it is enough to turn the screws H and L alternately in one direction or another by a small step of 1/5. 1/6 of a turn and immediately check the result of the carburetor adjustment in real work. This is one of the easy ways to get a good setup.

The material contains information on how to tune the chainsaw carburetor and check the tuning result.

Chainsaw carburetor adjustment using the example of STIHL MS 250

Author: Administrator Post Date

The need for the operation “Adjusting the chainsaw carburetor” is determined by the color of the spark plug electrodes: if black, it means over-enrichment, if brick-gray, it means the norm;.
The main role in adjusting the carburetor of the Stihl chainsaw is played by the upper screw (closest to the muffler). According to the factory parameters (indicated on the chainsaw cover), it should be unscrewed by 1 turn, and then it must be corrected. If you unscrew it, then the working mixture is enriched (more gasoline gets into the air-fuel mixture), if this screw is screwed in, then the working mixture becomes lean (less gasoline gets into the air / fuel mixture).

Adjusting the carburetor of the STIHL MS 250 chainsaw (with rev counter):

Before adjusting the Stihl chainsaw carburetor, it is necessary to service the chainsaw (clean the chainsaw carburetor, wash the chainsaw engine, replace the spark plug, clean the air filter, check the chain tension, adjust the idle speed, warm up the engine).

1. Screw in the screws “H” and “L” (on a muffled chainsaw) as far as the stop, and then unscrew both by 1 turn.
2. Start the chainsaw and warm it up. Give full throttle and screw “H” to achieve maximum engine speed equal to 14000 rpm. By the tachometer (by the engine speed meter). Hold maximum revolutions for adjustment no more than 10 seconds!
3. Using the bolt “LA” of the idle speed stop, make the chain start to move, and then turn this bolt ¼ turn counterclockwise.
4. If, after this adjustment of the carburetor of the chainsaw, the idle speed is not stable, and the chainsaw does not accelerate well, then the screw “L” must be slightly turned counterclockwise until the chainsaw begins to quickly gain speed and work well at idle. Then correct the bolt “LA” (idle speed on the tachometer should be 2800 rpm).

Note: It will not work to adjust the carburetor of the chainsaw if there is air leakage into the engine from the side (through the gasket under the carburetor, through the accelerator pump of the carburetor, through the seals of the chainsaw crankshaft, or elsewhere).

Adjusting the carburetor of the Stihl 180 chainsaw.

To adjust the carburetor of the Stihl 180 chainsaw, there is only one screw. The idle speed adjustment screw.

1. Standard idle speed adjustment (abbreviated x.X.): turn the screw counterclockwise until it goes tight, then we do two turns clockwise, and that’s it.
2. If the rpm is too low, turn the screw clockwise until the chain starts to move, and then turn the screw 0.5 turn counterclockwise.
3. If the rpm is too high, turn the screw counterclockwise until the chain stops rotating, and then turn the screw another 0.5 turn counterclockwise.

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That’s it, the Stihl 180 chainsaw carburetor adjustment is completed.


Chainsaw carburetor adjustment Stihl may be needed when the quality of the fuel changes, the altitude at which the Stihl chainsaw is operated (vacuum), as well as when the atmospheric pressure, temperature and humidity of the air change. Chainsaw carburetor setting allows you to achieve excellent chainsaw performance when external operating conditions deteriorate. Also, adjusting the carburetor of the chainsaw prevents oil starvation and engine breakdown due to insufficient lubrication entering the cylinder with a lean fuel mixture.

Tip: It is very good to use a special device to check the engine for leaks, i.E. Special pump with pressure gauge. First, remove the carburetor on the chainsaw, and install a sealed plate plug with a flange on the cylinder inlet window to connect the hose from the pump. The spark plug can also be sealed with a sealant for airtightness. It is also necessary to remove the muffler, and install a sealed plate with a rubber gasket on the cylinder outlet window. Then you need to put the piston at top dead center and connect the hose from the pump to the flange. Then it is necessary to pump air into the engine up to 0.9 atm. And look at the pressure gauge needle. If it is in place, then the piston engine is sealed. Then we release the air, switch the device (pump) and begin to pump out air from the cylinder, creating a vacuum in the engine with a pressure gauge reading of 0.5 atm. We look at the arrow of the pressure gauge. If it is in place, then there is no air leakage through the oil seals or other seals in the engine (which impairs the operation of the chainsaw and makes it impossible to correctly adjust the carburetor of the chainsaw). Thus, we check the engine for air leakage and compression.


The chainsaw carburetor is part of the fuel system of a chainsaw, designed for foggy mixing of gasoline with air and metering the supply of this fuel mixture into the engine cylinder.

Note: The chainsaw carburetor mixes gasoline with air in a ratio of 1:14, i.E. 1 part gasoline with oil is mixed with 14 parts of air, and adjusting the carburetor of the chainsaw ensures the correct ratio of these components of the fuel mixture.

Checking and subsequent replacement of defective membranes

Stihl 180 chainsaw carburetor membrane repair kit

Carburetor repair and cleaning without spare parts

There are situations in life in which it is simply vital to repair the saw, but the necessary components are not at hand. For such cases, there is the following method: take out the carburetor, remove the membranes, and then put the rest of it in acetone and let it soak. Acetone will remove debris that is blocking the passage of various fluids. This method will not hit your pocket, but it is not reliable. Such repairs will not ensure the long operation of the chainsaw, since outdated membranes have not been replaced.

Common malfunctions of the Stihl 180 carburetor

Malfunctions that can be solved by repairing the carburetor: It is worth noting that diagnostics cannot always correctly indicate the problem. There are times when the same “symptom” arises for different reasons. And sometimes diagnostics can give false information, as a result of which you cannot correctly eliminate the cause of the breakdown. Pay due attention to diagnostics, but do not overestimate its importance.

The tool does not keep idling, and sometimes the revolutions “walk”. Most likely the idle jet is clogged. It is urgent to clean it, otherwise the saw will not be able to perform its functions. Another possible cause is a malfunction of the fuel system.

Sometimes this problem is solved by unclogging the valve that limits the fuel tank. This valve regulates the output of gasoline and the passage of air. Do not forget to adjust the carburetor by changing the amount of air that is supplied to it. details about this operation can be found in the instructions included with the brand new chainsaw.

The carburetor of the Stihl chainsaw, without disassembling, can only be adjusted for the number of revolutions produced at idle. It is impossible to increase or decrease the fuel supply in various modes. Manufacturers have limited access to this adjustment by removing special screws. If faults are found in this system, it is possible, with experience, to increase the gap between the needle valve and the wall.
The saw does not start. The solution is the same as in the previous paragraph.

The tool began to consume more fuel, while its power was significantly reduced. Gasoline consumption and power are subjective concepts. To accurately determine these indicators, one cannot do without visiting special firms specializing in this tool.

Well, if these two indicators are visible “on the face”, then follow these steps:

Check if the chain is dull. A dull chain has a lower efficiency, and therefore the saw consumes more fuel.

Examine the fuel tank. Perhaps it has formed a small mechanical damage, through which gasoline leaves imperceptibly.

Inspect the muffler carefully.

Clean the cooling system and exhaust system.

The unit stalls immediately after operation or warming up. Experts call it hot.

The most common reasons are:

  1. Lack of air entering the carburetor. Replace inlet and outlet valves.
  2. Breakdown of the cooling system (overheating). It is possible that foreign objects have entered the pipes with cold air and must be removed.
  3. Chainsaw stalls when position is changed. This only applies to tilting to the side, in the vertical state the saw functions normally. This problem even applies to serviceable chainsaws, because during the development the designers made a small mistake. The fuel system Stihl 180 has a special design, in which the fuel cannot escape from the tank on its side. Sometimes the problem lies in the clogging of the gas pump.
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The procedure for parsing, as well as tuning the carburetor of the Stihl 180 chainsaw: In order to carry out a high-quality repair of the carburetor, you will need to remove it. This is not difficult to do, but you need to be extremely careful. To begin with, we will prepare the workplace: install the lighting, lay out all the necessary tools. Understand that the carburetor is the main saw unit where the fuel and gasoline flows intersect. For stable operation, they must be cleaned of foreign debris.

Therefore, before the main work, you need to do the following:

  • Remove and clean the muffler.
  • Make sure there are no problems with fuel supply and combustion.
  • Check the serviceability of the air and cooling filters.

Repair and adjustment of the carburetor of the Stihl 180 chainsaw

The Stihl 180 is a German chainsaw designed for gardening, logging, site clearing and other woodworking. Many people love it for its compactness and ease of use. The instrument combines seemingly opposite qualities. Power and maneuverability. German designers have tried to create this sample, but the MS 180 Stihl also has disadvantages that users face in various operating modes. Like all mechanisms, it tends to fail. What to do in such cases and is it worth contacting the workshops?

The main stages of work (removal of the carburetor)

The best option would be to watch the tutorial. Fortunately, there are dozens of them on the Internet. There you will be told everything in detail and professionally. As the saying goes: “It is better to see once than hear a hundred times” (in our case, read it). Schematically, this process can be written as follows: remove the protective cover, remove the rods and, finally, unscrew the unit to work with it.

Stihl chainsaws characteristics

ModelWorking volume (cm 3)Power (kW / hp)Weight, kg)Specific gravity (kW / kg)Standard tire (cm)Standard chainStart aidsChain tensionerengine’s type
Petrol-powered saws for sawing wood and for maintenance of the land
MS 17030.11.3 / 3/8 ″ P.1.3In front2-stroke
MS 18031.81.5 / / 8 ″ P-1.3In front2-stroke
MS 180 C-BE31.81.5 / / 8 ″ P-1.3ErgoStartFast2-stroke
MS 18131.81.5 / 2.04,32.93550-3 / 8 ″ P- 1.3Lateral2-MIX
MS 181 C-BE31.81.5 / / 8 ″ P- 1.3ErgoStartFast2-MIX
MS 192 C-E30.11.3 / / 8 ″ P-1.3ErgoStartLateral2-stroke
MS 21135.21.7 / 2.34,32.53550-3 / 8 ″ P-1.3Lateral2-MIX
MS 211 C-BE35.21.7 / / 8 ″ P-1.3ErgoStartFast2-MIX
MS 23040.22.0 / 2.74.62,33550-3 / 8 ″ P-1.3In front2-stroke
MS 23140.62.0 / / 8 ″ P-1.3Lateral2-MIX
MS 25045.42.3 / / 8 ″ P-1.3Lateral2-stroke
MS 250 C-BE45.42.3 / / 8 ″ P- 1.3ErgoStartFast2-stroke
MS 25145.62.2 / / 8 ″ P- 1.3Lateral2-MIX
MS 27150.22.6 / ″. 1.6Lateral2-MIX
MS 29155.52.8 / ″. 1.6Lateral2-MIX
MS 39064.13.4 / / 8 ″. 1.6Lateral2-stroke
Petrol saws for forestry
MS 20135.21.8 / / 8 ″ P- 1.3Lateral2-MIX
MS 241 C-M42.62.2 / / 8 ″ P-1.3DecompressorLateral2-MIX M-Tronik
MS 26050.22.6 / ″. 1.6DecompressorLateral2-stroke
MS 26150.22.8 / ″. 1.6DecompressorLateral2-MIX
MS 261-VW50.22.8 / ″. 1.6DecompressorLateral2-MIX
MS 36159.03.4 / / 8 ″.1.6DecompressorLateral2-stroke
MS 36259.03.4 / / 8 ″.1.6DecompressorLateral2-MIX
MS 362-VW59.03.4 / / 8 ″.1.6DecompressorLateral2-MIX
MS 44070,74.0 / 5.46,31.65072-3 / 8 ″. 1.6DecompressorLateral2-stroke
MS 440-W70,74.0 / 3/8 ″. 1.6DecompressorLateral2-stroke
MS 44170,74.2 / / 8 ″.1.6DecompressorLateral2-MIX
MS 441 C-M70,74.2 / / 8 ″.1.6DecompressorLateral2-MIX M-Tronik
MS 66091.65.2 / / 8 ″.1.6DecompressorLateral2-stroke
MS 880121.66.4 / ″.1.6DecompressorLateral2-stroke
Special saws
MS 150 TC-E23.61.0 / 1/4 ″ P. 1.1ErgoStartLateral2-MIX
MS 192 T30.11.3 / / 8 ″ P-1.1Lateral2-stroke
MS 201 T35.21.8 / / 8 ″ P-1.3Lateral2-MIX
MS 192 C-E Carving30.11.3 / 1/4 ″ P- 1.3ErgoStartLateral2-stroke
MSE 160 C-BQ1.64.13550-3 / 8 ″ P-1.3Fast
MSE 180 C-BQ1.84.24055-3 / 8 ″ P-1.3Fast
MSE 220 C-Q2.26.24566. 3/8 ″. 1.6Lateral