Stihl Ms 180 Idle Adjustment

The Stihl 180 chainsaw (aka Stihl MS 180) is the most popular and recognizable model of the German brand. This chainsaw is simple and reliable. The only unit that requires close attention is a carburetor. This article will discuss the carburetor adjustment, its repair and maintenance.

What carburetor is used on a Stihl 180 chainsaw

The Stihl 180 chainsaw has a Japanese Zama carburetor of membrane type. Some users are confused by the inscription China on the carburetor. Yes, indeed they are going to China. But the plant is owned by Stihl (Stihl), and quality is still high. However, the chainsaw also has Chinese counterparts with corresponding carburetors. But such saws are usually cheaper than the original.

Stihl Ms 180 Idle Adjustment

How the Stihl 180 carburetor works: device, principle of operation

The main components of the Stihl 180 chainsaw carburetor are the following components:

  • fuel pump (with internal diaphragm);
  • main (membrane) chamber;
  • diffuser;
  • throttle and air flaps;
  • needle valve;
  • fuel jets;
  • nozzle with valve;
  • idle speed screw.

The principle of operation is as follows. The chainsaw crankcase is connected to the fuel pump in the carburetor by a special channel. Due to the alternating stroke of the piston, a vacuum is created in the engine crankcase. As a result, the diaphragm rises in the fuel pump and the valve for supplying fuel to the carburetor opens.

Further, the fuel passes through a filter element (mesh) and through a special channel enters the main chamber. A control membrane is installed in this chamber, which regulates the fuel supply by pressing the rocker arm, which in turn lowers the needle valve.

For raising the control membrane is responsible for the vacuum that occurs in the carburetor diffuser due to the rotation of the air, throttle valves. Once the engine has started, the mixture needs to be leaner. We lower the air damper, the vacuum in the diffuser is minimal, the membrane falls into place.

From the main chamber, fuel enters the diffuser using a nozzle with a check valve, or through idle jets (when the gas throttle is closed). There it mixes with the intake air and the finished mixture enters the engine cylinder. The non-return valve prevents air from the diffuser from entering the main chamber.

Carburetor Adjustment Stihl 180 Chainsaw

Usually, special screws are responsible for the quantity and quality of fuel entering the diffuser, by adjusting which we change the cross section of the fuel channel. But on the used carburetor of the Stihl 180 chainsaw, to facilitate the operation of the saw, these two screws are missing.

The channels are designed so that the optimum amount of fuel gets into the diffuser at all engine speeds. And for the adjustment here, the LD screw is responsible, the rotation of which regulates the air supply to the idle jet. Due to which there is a change in engine speed.

So, to adjust the carburetor of the Stihl 180 chainsaw, you will need an ordinary flat screwdriver and an electronic tachometer (not necessary). The adjustment algorithm is as follows:

  1. Check air filter. If necessary, replace the filter element.
  2. Screw the LD screw counterclockwise to the end, and then unscrew by 2 turns. Attention, the left thread! A hole for a screwdriver is provided for access to the screw on the saw body. Start the engine and warm up for 5-7 minutes.
  3. Turning the LD screw slowly clockwise, arbitrarily adjust the idle speed. There are 2 possible situations:
  1. The engine idle speed is very small. The engine does not keep idle. Turn the LD screw until the saw starts to rotate, and then turn the screw 1/2 back (the chain should stop).
  2. The saw spins idling. In this case, slowly turn the screw counterclockwise until the chain stops, then turn the screw another 1/2 turn in the same direction.

If after all the manipulations with the carburetor settings, the chain continues to spin at idle, you need to give the saw to the dealer at the service center.

The video below provides a detailed adjustment of the carburetor of the Stihl 180 chainsaw using an electronic tachometer.

Carburetor Repair Stihl 180 Chainsaw

The main malfunctions of the carburetor of the Stihl 180 chainsaw include the following.

  1. Gas does not enter the carburetor. The commonplace reason is a fuel pump failure. The diaphragm has lost elasticity or has lost weight. This happens due to material fatigue during prolonged use. As a result, with a vacuum in the engine, the diaphragm does not rise and does not open the fuel channel with the valve. It can be replaced by a spare from the repair kit by dismantling the carburetor.
  2. Gasoline may also not flow due to a clogged filter element (mesh) in the channel between the fuel pump and the needle valve. It is also treated with a replacement from the repair kit.
  3. Carburetor overflows. It’s not hard to guess that the problem lies in the main camera. Dirt particles enter the cavity between the needle and the channel, i.e. the valve does not completely close the channel when necessary and fills the chamber. Very often, the membrane ceases to fulfill its functions due to stretching (natural wear). As a result, when lowering, the membrane does not fully raise the needle, and fuel continues to flow. The main membrane is also part of the repair kit. Replace it is not difficult.
  4. Very often, after winter downtime, owners of Stihl 180 chainsaws face a difficult start. In this case, the valve sticks in the nozzle. The manufacturer recommends that you burn the remaining gasoline in the carburetor before putting the chainsaw in storage. Gasoline is prone to evaporation and during long-term storage, engine oil remains in the carburetor, upon contact with which the nozzle valve begins to stick to the body. As a result, fuel does not enter the diffuser. Since the nozzle is not part of the repair kit, you have to knock it out and rinse thoroughly. This must be done very carefully.
  5. If an idle nozzle or nozzle is clogged, it is enough to blow them with compressed air. Or rinse with gasoline, in 90% of cases it helps. But you cannot use needles or wires, as there is a risk of changing the flow area, thereby changing the throughput of the nozzles.

A common problem due to which the Stihl 180 is unstable is the loss of the retaining ring on the axis of the throttle, as a result, it begins to dangle and play, which in turn leads to interruptions in work.

So, you decided to remove the carburetor and carry out diagnostics. The removal procedure is as follows:

  1. Pull the trigger and lower the choke lever down. We turn the latch and remove the chainsaw cover.
  2. We unscrew both fastening nuts with a socket wrench for 8 and remove the air filter with the housing.
  3. Remove the thrust of the gas (throttle) carburetor.
  4. Disconnect the cable from the control lever
  5. We take out the engine control lever from its place. At the same time, we disconnect the draft of the air damper.
  6. Pulling the carburetor towards you, remove it from the studs. Do not forget to disconnect the fuel supply hose.

A more detailed and intuitive algorithm for removing the carburetor from a chainsaw is presented in the video.

As for the disassembly of the carburetor chainsaw Stihl 180, then everything is simple. 1 bolt is unscrewed on the cover of the fuel pump and 4 bolts on the cover of the main chamber. This is enough to change all the necessary components from the repair kit.

After disassembling, the carburetor must be rinsed in gasoline, and the channels and jets must be blown with compressed air. In no case should you blow out the carburetor under high pressure and in the assembled state. Otherwise, you may stretch the membrane or diaphragm. The carburetor will stop working properly.

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In order to assess the state of the filter mesh and membrane, you need to perform the following sequence of actions:

  1. Unscrew the screw.
  2. We evaluate the condition of the membranes, remove dust and dirt, if necessary, change the membrane to a new one. Everything should be clean under the membrane There should be no dirt on the membrane.

Video: Stihl Ms 180 Idle Adjustment


  • We check the condition of the filter screen for dirt, if any, we clean it.
  • We collect everything back and disassemble the carburetor on the other hand. Having unscrewed 4 bolts, remove the cover, remove the membrane and evaluate the condition of the insides. Just need to unscrew 4 screws
  • To check fuel supply by putting a hose on the fitting.
  • We blow it with our mouth, while with our fingers we open the needle valve, everything should work clearly.
  • We blow 2 holes in the nozzles with the same hose, they should sulk calmly, without excessive force. If necessary, clean with a standard WD-40 cleaner.
  • Remove the nozzle nozzle located on the right and clean it with a thin wire from the back.
  • We clean and collect everything. When installing the cover, follow the correct installation. See the photo below.
  • As for the Stihl 180 carburetor repair kit, it includes a set of gaskets for covers, a diaphragm and a membrane, a needle valve, a rocker with an axle and a spring. The price of such a kit is from 100 to 400 rubles.

    Advantages and disadvantages

    Zama carburetors are very reliable and easy to operate. Specifically, a carburetor is installed on the Stihl 180 chainsaw, on which there are no screws to adjust the quality and quantity of the mixture, as we are used to. One screw greatly simplifies the adjustment.

    The membrane carburetor has no significant drawbacks. With such a carburetor, the chainsaw works in any position. With side cut, vertical, etc.

    Despite the above advantages, the carburetor is sensitive to fuel quality. In addition to clean air from the air filter, it is required to supply purified fuel from the gas tank to the carburetor. But this is not always possible, therefore, at least once every six months it must be cleaned and purged.

    How much is a new carburetor

    Stihl 180 chainsaws are in great demand, primarily due to their reliability. The carburetor was no exception and also quite reliable and unpretentious. Adjustment or repair of the carburetor is required only after prolonged use, at least 5-7 years later (with an average load). The setup process itself is maximally simplified by Stihl engineers, this is the first chainsaw in which only one screw is provided for adjustment.

    Home »Stihl Ms 180 Carburetor Adjustment

    Related posts

    The need for the operation “Adjusting the carburetor of the chainsaw” is determined by the color of the electrodes of the spark plug: if black. means over-enrichment, if brick-gray. means normal, if snow-white coating on the electrodes of the candle. means lean mixture.
    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 characteristics (indicated on the lid of the chainsaw), it must be unscrewed by 1 revolution, and then you need to adjust it. if you unscrew it, the working mixture is enriched (it gets into the air-fuel mixture than just gasoline), if you screw such a screw, the working mixture becomes leaner (less gasoline gets into the air-fuel mixture).

    Before adjusting the carburetor of the Stihl chainsaw, you need to carry out technical maintenance of the chainsaw (cleaning the carburetor of the chainsaw, rinse the engine of the chainsaw, replace the spark plug, clean the air filter, check the chain tension, adjust the idling speed, warm up the engine). See also: Banks of Kremenchug. Continue the adjustment:

    1. Screw the screws “H” and “L” (on the muffled chainsaw) in full, and then unscrew both by 1 revolution.
    3.2. Start a chainsaw and warm it up. Give full throttle and reach with the “H” screw so that the maximum engine speed is 14,000 rpm. by tachometer (by engine speed counter). The highest revolutions for adjustment to keep no more than 10 seconds!
    3. To reach the idle stop bolt “LA”, so that the chain starts to move, and at the end turn the myth bolt на turn counterclockwise.

    MS 180 will not start. let’s figure it out!

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    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 you need to turn the “L” screw a little counterclockwise until the chainsaw starts to rapidly gain speed and work perfectly at idle. After that, adjust the bolt “LA” (idle on the tachometer must be 2800 rpm).

    Note: You cannot adjust the chainsaw carburetor if there is air leakage into the engine of those unfamiliar (through the gasket under the carburetor, through the carburetor accelerator pump, through the chainsaw crankshaft oil seals, in other words, here and there).

    Chainsaw Carb Adjustment Stihl is required when changing the properties of fuel, altitude, a busy Stihl chainsaw (vacuum), as well as when changing atmospheric pressure, temperature and humidity. Setting the carburetor of the chainsaw allows you to achieve a good performance of the chainsaw with the deterioration of the external operating criteria. Also, adjusting the carburetor of the chainsaw helps prevent oil starvation and engine damage due to insufficient lubrication entering the cylinder with a lean fuel consistency.

    Tip: To check the density of the motor, it is great to use a special device, i.e. special pump with pressure gauge. First, you need to remove the carburetor on the chainsaw, and install a sealed plate plug with a flange on the inlet window of the cylinder to connect the hose to the pump. Spark plug for density, too, of course put on a sealant. You also need to remove the muffler, and install a sealed plate with a rubber gasket on the exhaust window of the cylinder. Then you need to put the piston at top dead center and connect the hose from the pump to the flange. Next, you need to pump air into the engine up to 0.9 atm. and look at the gauge needle. if it is in the workplace, it means the piston motor is tight. Then we release air, switch the device (pump) and start pumping air out of the cylinder, creating a vacuum in the engine with a pressure gauge reading of 0.5 atm. We look at the pressure gauge needle. if it is in the workplace, it means there are no air leaks in the engine through gaskets or other seals (which aggravates the operation of the chainsaw and does not even make it possible to correctly adjust the chainsaw carburetor). In this way, we check the engine for air leaks and compression.

    Adjustment carburetor chainsaw.

    Why it may be necessary to adjust the carburetor even if it seems to start and work? Carb adjustments should be optimal.

    In general, the carburetor has a very important effect on the operation of the chainsaw, it is its "brain" indicating how much air and fuel mixture to feed into the cylinder and in what proportion. If the mixture is “rich”, that is, the fuel in it will be more than it should be, then as a result we have a loss of power, deposits on the walls of the cylinder and piston. Which in turn can lead to failure of the chainsaw. In turn, the “poor” mixture, which has more than normal air in its composition, also leads to loss of power, insufficient lubrication of the CPG, scuffing and possible “jamming” of the engine. Optimal settings carburetor chainsaw allows you to get maximum power, extend engine life, provide minimal emissions!

    Poor and rich mix

    A little more about the "poor" and "rich" mixtures.

    “Rich blend”

    Read the same

    A “rich” mixture is a fuel mixture in which the amount of fuel supplied to the carburetor exceeds the norm. In this case, the fuel does not have time to burn out completely and less energy is produced than with the optimal ratio of fuel to air. Partially unprocessed fuel enters the muffler, then chainsaw smokes a lot.

    “Poor mix”

    There is an excess of air in the “poor” mixture, which is also not good, as it has its drawbacks. Namely: insufficient energy during a flash (which means loss of power as a result), excessive heating of the cylinder due to insufficient lubrication and high revolutions, which leads to scoring, and not far from the engine "jamming" there.

    Carb adjustment chainsaws

    Most chainsaws have three adjustment screws on the carburetor. In order about each:

    • T. Idling screw. The idle screw is responsible for the throttle position when the throttle grip is fully released. If the throttle valve is not open enough, the engine will stall with the handle released as the valve will shut off the flow of the fuel mixture. If the throttle valve is opened by a larger amount than it should be, then the chain will rotate, which is strictly prohibited by safety precautions when working with a chainsaw.
    • L-screw low speed adjustment. This screw adjusts amount of fuel in the fuel mixture when the chainsaw is idling. If the amount of fuel is large, the engine will stall under load, if the fuel is not enough, the result will be overheating of the engine, badass, and so on.
    • H-screw adjusts high revs. Responsible for amount of fuel in a mixture during operation of a chainsaw. If given adjustment tuned for more amount of fuel, then the engine works "unacceptably" and smokes, but if it’s less, then we get too high revs and overheating.

    Stihl MS 180 HOW TO ADJUST A CARBURETTOR How to adjust carburetor Stihl chainsaw MS 180

    How to adjust carburetor Stihl ms 180 what are the revolutions of min and max? And also a similar video about the adjustment on mine.

    Read the same

    STIHL carburetor adjustment Stihl MS 180

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    Carb adjustment step by step

    1. Check the condition of the air filter. We remove it and either clean it or change it. If the air filter is clogged with dirt and sawdust, the operation of the chainsaw will not be normal.
    2. Check the condition of the muffler. It should be clean and unbroken. Read more about cleaning the muffler HERE.
    3. Before you start adjusting the carburetor, you should fill the fuel tank at least half.
    4. If chainsaw If it is able to start, then it should be allowed to work for several minutes so that it warms up. If the adjustment is carried out “cold”, then the mixture will be re-enriched after heating.
    5. To begin the adjustment, it is necessary to adjust the idle speed-screw L. It is highly desirable to have a tachometer, then we focus on 2700 rpm. If not, then we need to find the highest idle speed. In this case, the chain should not rotate. If it still turns (the chain is finite, not the Earth), then we achieve its stop by rotating the T screw. The sound of the chainsaw should be like listening to the file below.
      http://benzopilatut.ru/wp-content/uploads/2016/01/Chainsaw-idle.wav
    6. We adjust the high revolutions. screw H. If we rotate it clockwise then the revolutions will increase, and if counter-clockwise. fall. We twist it until there are dips in the ignition. After that, we turn it about one fifth of a turn. The sound of the chainsaw when working at maximum speed should be the same as when listening to the file below.
      http://benzopilatut.ru/wp-content/uploads/2016/01/Chainsaw-max-revs.wav
    7. Check how chainsaw gaining momentum. She must dial them smoothly and quickly. If the revolutions grow slowly, then slightly turn the screw L.

    If you still have questions, write in the comments or better in the VK group.

    Remember that the optimal carb adjustment is: