How to Assemble a Stihl 180 Carburetor

The stihl ms 180 chainsaws are designed in such a way as to facilitate their operation as little as possible by inexperienced users. To do this, some settings available on the more powerful Stihl models were canceled in the carburetor of the saw. But there is still the opportunity to adjust, and repair, as well as adjusting the carburetor of the Stihl 180 chainsaw with your own hands, is possible.

How to Assemble a Stihl 180 Carburetor

When to adjust your Stihl 180 carburetor

To begin with, it’s worth deciding why, in general, you may need to adjust and repair the stihl ms 180 carburetor. So, you need to do this in the following cases:

  • if the chainsaw does not keep idle;
  • repairs may be required if the saw does not start;
  • there is a loss of power;
  • increased fuel consumption;
  • chainsaw does not develop maximum speed.
  • stalls at speed.

This list can be continued for a long time, but we have identified the main reasons. Before proceeding with the adjustment, it is necessary to know what are the main parts of the carburetor on the Stihl 180 chainsaw, and who produces it.

Carburetor Stihl 180

So, the stihl ms 180 carburetor is designed and manufactured by a subsidiary of Stihl, called Zama. Original carburetors on their case have a company logo guaranteeing product quality.

Fuel pump

A fuel pump is installed directly in the carburetor body, which operates under the influence of an air pulse from the crankcase of the chainsaw, transmitted through special channels. A diaphragm is installed in the pump, and it is it that is responsible for pumping fuel under the influence of a pulse. A gasket is installed between the diaphragm and the housing, which is responsible for the tightness of the fuel pump.

Distribution chamber

In the distribution chamber, as in the fuel pump, there is also a membrane that opens and regulates the fuel supply by pressing a special rocker, while raising its needle valve.

The chamber cover is the compensator body, which is mounted on the carburetor with four screws; a gasket is installed between the body and the cover, which increases the height of the chamber and is responsible for sealing.

Nozzle

The fuel injector is mounted in the carburetor body in such a way that it is a connecting link between the distribution chamber and the cavity in which the throttle valve is installed. Simultaneously with the fuel, air is supplied to the nozzle and an air mixture is formed. The nozzle has a check valve that blocks the flow of air in the reverse sequence, that is, from the throttle chamber to the distribution chamber.

Throttle damper

A throttle is installed in the carburetor housing and is responsible for increasing the supply of the fuel mixture directly to the engine cylinder. At the moment of pressing the gas, the throttle opens slightly, thereby increasing the channel capacity and fuel from the carburetor cavity, rushes into the cylinder in a larger volume.

The combustion of a larger volume of fuel increases the amount of energy generated, which affects the power and speed of the processes. The damper is mounted on a shaft passing through the entire carburetor body. At the output of the shaft from the housing, a mount for the gas cable is installed, a conical, adjusting screw responsible for idle speed adjustment is located nearby. By tightening the screw, you can slightly adjust the position of the shaft and the shutter installed on it, thereby increasing or decreasing the idle speed by slightly opening or vice versa closing the shutter.

Air damper

The carburetor air damper is installed on the opposite side of the throttle and is responsible for starting a cold engine, its control is carried out by the engine control lever. For a cold start, the air damper is completely closed, for normal operation open.

Carburetor adjustment Stihl 180

The carburetor of the Stihl 180 chainsaw, indiscriminately, can only be adjusted by the number of revolutions at idle. It is impossible to increase or decrease the fuel supply in various modes with the help of special screws. The manufacturer restricts access to adjustments and does not install these screws. How to adjust the carburetor to the correct idle speed is described in great detail in the manufacturer’s instructions.

In the event of certain malfunctions and experience, it is possible to increase or decrease the fuel supply by increasing the clearance when opening the needle valve.

To increase the feed, the rocker of the needle valve in the distribution chamber must be bent up, and to decrease, down. Thus, the stroke of the needle and, accordingly, the throughput of the valve are regulated.

It is not necessary to carry out the adjustment on your own, because it must be done very accurately and, with an error, returning the initial position of the rocker arm is almost impossible.

Why the Stihl 180 carburetor overfills and some characteristic malfunctions

After we examined the carburetor device, determining the reason why the fuel enters the combustion chamber in a larger volume is not difficult. This happens due to wear on the gasket between the compensator cover and the carburetor body. You may ask how this can affect?

The answer is simple, shrinking, the gasket releases the diaphragm located on top of it a fraction of a millimeter down. She, in turn, will put more pressure on the rocker arm of the needle valve, it will open more than expected and the fuel will flow in excess (begin to overfill).

Another reason is the extension of the diaphragm itself, this occurs as a result of natural wear. It is impossible to prevent this process, but it is possible to solve the problem by periodically changing all gaskets, carburetor diaphragms, and the fuel pump. There is a repair kit for this.

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When cleaning the chainsaw with compressed air, in no case should you blow into the fuel pipe, this can lead to an extension of the diaphragm.

Frequent breakdown of a Stihl carburetor and how to avoid it

A common cause of failure of the carburetor on a Stihl chainsaw is sticking of the valve in the nozzle. The cause of sticking is a violation of the storage of the chainsaw, or rather the manufacturer’s instructions Stihl 180 on proper preparation for storage.

As follows from the instructions, before long-term storage, it is necessary to drain the fuel from the tank, then start the saw and burn gas from the carburetor. Failure to comply with this elementary rule entails the following consequences. The forsknui valve, being in direct contact with the fuel, sticks to the body, since gasoline gradually evaporates and only sticky oil remains. The nozzle cannot be replaced, because they are not in the repair kit, you can only try to knock it out and rinse, which is not always possible to do without ruining the nozzle.

Removal and Installation Algorithm

In cases where you need to clean the Stihl 180 carburetor or disassemble it, first you need to remove the assembly from the chainsaw. This must be done in compliance with a certain algorithm of actions:

  1. Attach a protective cover for the chainsaw to the tire.
  2. Remove the top cover of the chainsaw.
  3. Unscrew the two nuts securing the air filter and carburetor.
  4. Remove the air filter housing.
  5. Disconnect wire from engine control lever.
  6. Carefully remove the lever from the seat in the housing, while disconnecting the air damper rod from it.
  7. Pull the carburetor towards you and disconnect the fuel supply as well as the throttle link.

To facilitate dismantling, you can further unwind the rear handle and disconnect the throttle rod from it first, and then only from the carburetor. This may be required, because without any experience disconnecting the thrust from the carburetor is quite problematic and easier to disassemble the handle first.

Install the part in place, following the reverse order of the algorithm.

When removing and installing the control lever of the chainsaw engine, you should be extremely careful, because the seat on the saw body is a weak link in the saw, and very often inexperienced users break it.

Dismantling the Stihl 180 carburetor

In order to blow, change gaskets or a needle valve, the carburetor must be disassembled. To do this, unscrew 4 screws on the cover of the compensator and one on the fuel pump.

Opening the case, you should be extremely careful, because if debris enters the carburetor inside, it will make it impossible to work. The thickness of the channels in it is comparable to the thickness of a thread or even a human hair.

A video on repairing a Stihl 180 carburetor can be seen below. In it, the master tells in detail about the problems and clearly demonstrates the entire repair process.

Conclusion

In conclusion, I would like to once again note that the Stihl carburetors, which are produced by its subsidiary Zama, are very reliable. With proper operation and storage, they are able to serve the entire time allotted to the chainsaw without repair.

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.

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.

Video: How to Assemble a Stihl 180 Carburetor


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.
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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.

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.
  • 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.

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    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 in Russia, 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.

    Who can repair carburetors

    All of the following applies to any chainsaw model, including gas trimmers, scythes and other equipment. Adjusted, of course, for design features.

    There is an opinion that it is better not to climb inside a chainsaw yourself. For those who are used to working with a hammer and sledgehammer, perhaps this is so. For the rest, any more or less accurate person who does not shake hands can correct any problem with his work. In general, this is work available to anyone.

    Faults that can be fixed by carburetor repair

    Let’s make a reservation right away. diagnosis is an insidious thing. Sometimes the same symptom occurs due to completely different reasons. But we will check everything and find it together. So:

    The chainsaw does not keep idle. Either she stalls at idle, or they walk, or high.

    The idle nozzle may be clogged. It needs to be cleaned. How to do it. more on that below. But so far about alternative reasons.

    It is possible that the problem is in the fuel system. Check fuel hoses, fuel supply.

    Sometimes problems with revolutions (or rather, their absence) are solved by cleaning the check valve of the fuel tank (gasoline tries to leave the tank, but the air does not return instead). It looks like the one shown below in the figure:

    Do not forget to adjust the carburetor in the only possible way. to change the amount of air supplied, which is reflected at idle very much. Everything is described in the instructions for the saw. For those who are too lazy to go into the instructions, here is a screenshot:

    The saw does not start

    A special case of the previous problem. The solution is required the same.

    Saw lost in power, increased fuel consumption

    Two very subjective indicators. In order to reliably state this or that, instrumental measurements are necessary. From the practice of repair organizations, very subjective things are often issued under one or another. In some cases, effects resulting from a dull circuit can be taken for loss of power. Naturally, the performance in this case will be low. Sometimes it seems that the saw is quieter (clogging of the cooling system, exhaust system). Increased fuel consumption may be due to leaks.

    Often the problem is the muffler, not the carburetor!

    Chainsaw stalls hot. after work and warming up

    • Problems with the carburetor (on how to eliminate and diagnose. below);
    • Overheating. problems with cooling. Clean your saw;
    • Lack of air supply;

    The chainsaw begins to stall or change speed when tilted to its side. In the vertical. everything is fine, when turning. the speed drops (or grows) and it stalls

    It is connected with the design features of its fuel system, filling the chambers. In addition, it is necessary to check the gas pump. sometimes the problem may be in it.

    The procedure and sequence for disassembling and adjusting the carburetor of the Stihl 180 chainsaw

    Preparatory work

    First of all, it is necessary to understand that the carburetor of any engine is a unit into which the flows of air and gasoline converge. Therefore, for its normal operation, these flows must come in a working, not clogged form. In addition, the combustion products in the engine must freely leave the chamber through the muffler. Therefore, every time, before repairing and adjusting the carburetor, we must check:

    • Intake air filter;
    • Remove and clean the muffler;
    • We check that there are no problems with the fuel system. supply hoses, fuel tank operation (operation of the breather for compensation of reduced pressure, see above);

    In principle, it is not even so vital to turn idle speed. Serviceable elements will already give normal performance characteristics.

    Carburetor removal

    The removal process is best shown in the attached video below. The basic minimum steps are also shown in order to bring the unit into working condition. Schematically, this process looks like this: remove the cover, traction, unscrew the unit.

    Replacing and checking membranes

    And specifically in this case, the rocker with a needle are also included in the kit, which are also subject to wear and in some cases require replacement. In a word, for the price of a new unit, you can repair an old almost unlimited number of times. If you consider that five. this is actually a lifelong set.

    Option to repair and clean the carburetor without the use of repair kits

    In some cases, the following method gives excellent results. we take out the carburetor, remove all the membranes (top and bottom), and then leave what is left, soak in acetone for several hours. Often foreign objects and substances simply fall into the jets and channels (sometimes, for example, traces of sealants are found there!). Therefore, a simple cleaning gives an excellent effect. No costs and membrane replacements. Although the decision to replace them must be taken locally, guided by their condition.

    Are Chinese carburetors reliable with Aliexpress?

    It may seem surprising, but quite. This unit has almost the only requirement. the accuracy of its manufacture. In terms of geometry, as a rule, everything is fine with him. It does not carry any excessive mechanical or chemical loads. Therefore, a simple replacement may well be an appropriate option for a long time to extend the life of a chainsaw, which costs quite decent money.