Stihl 180 Chainsaw: Carburetor Adjustment.

Chainsaws Stihl ms 180 are designed in such a way as to maximally facilitate their operation by inexperienced users. To do this, in the carburetor saws have been eliminated some of the settings available on the more powerful models Stihl. But the ability to customize is still there, and repair, as well as adjustment of the carburetor chainsaw Stihl 180 with your own hands, is possible.

When you need to adjust the “Stihl 180” carburetor?

First of all, it’s worth deciding why it may even be necessary to adjust and repair the carburetor Stihl ms 180. So, this should be done in the following cases:

  • if the chainsaw does not keep idle;
  • repairs may be required if the saw does not start;
  • power loss is observed;
  • increased fuel consumption;
  • chainsaw does not develop maximum speed.
  • stalls when gaining momentum.

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

The arrangement of “Stihl 180” carburetor.

So, carburetor Stihl ms 180 is developed and manufactured by a subsidiary of the company Stihl, called Zama. Original carburetors, on its case, have a company logo that guarantees the quality of products.

Fuel pump

Directly in the carburetor case, there is a fuel pump installed, which operates under the action of an air pulse from the crankcase of the chainsaw, which is transmitted through special channels. A diaphragm is installed in the pump, and it is this component that is responsible for pumping fuel under the action of a pulse. Between the diaphragm and the body has installed the gasket, 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 on a special rocker, raising its needle valve.
The lid of the chamber is the body of the compensator, which is mounted on the carburetor with four screws, a gasket is installed between the housing and the lid, which increases the height of the chamber and is responsible for sealing.


The fuel injection nozzle 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, the 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 reverse order, that is, from the throttle chamber to the distribution chamber.

Throttle valve

The throttle valve is installed in the carburetor body 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 valve opens slightly, thereby increasing the channel capacity and fuel from the carburetor cavity rushes into the cylinder in a larger volume.
Combustion of a larger amount of fuel increases the amount of energy produced, which affects the power and speed of the processes. The valve is installed on the shaft of the carburetor passing through the entire body. At the shaft exit from the body, a gas cable mount is installed, a cone-shaped adjusting screw is located next to it, which is responsible for setting the idle speed. By twisting the screw, you can slightly adjust the position of the shaft and the flap mounted on it, thereby increasing or decreasing the idling speed by slightly opening or closing the flap.

Air damper

The carburetor choke is installed on the opposite side of the throttle valve and is responsible for starting a cold engine, and it is controlled by the engine control lever. For a cold start, the air damper is completely blocked, for normal operation, it is opened.

Adjusting the Stihl 180 carburetor.

The carburetor chainsaw Stihl 180, indiscriminately, can only be adjusted by the number of revolutions at idle. It is not possible to increase or decrease the fuel supply in various modes with the help of special screws. The manufacturer restricts access to the 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, the fuel supply can be increased or decreased by increasing the clearance when opening the needle valve.
To increase the supply, the rocker of the needle valve in the distribution chamber must be bent up, and to decrease, down. Thereby, the stroke of the needle and, accordingly, the throughput of the valve are regulated.
You should not make adjustments yourself, because it must be done very precisely and it is almost impossible to return the initial position of the rocker arm in case of an error.

Why pours the Stihl 180 carburetor and a few characteristic faults.

After we have considered the carburetor device, it will not be difficult to determine the reason why fuel enters the combustion chamber in a larger volume. It happens due to the wear of the gasket between the cover of the compensator and the carburetor body. Do you ask how it can affect?
The answer is simple, shrinking, the gasket lets the diaphragm located on top of it a fraction of a millimetre down. It, in turn, will push more pressure on the needle valve, it will open more than it should be and the fuel will go in excess (it will start to pour).
Another reason is the stretching of the diaphragm itself. It occurs as a result of normal wear and tear. It is impossible to prevent this process, but you can solve the problem by periodically changing all the gaskets, carburettor diaphragms, and the fuel pump. For this, there is a repair kit.
When cleaning the chainsaw with compressed air, in no case can not blow into the fuel tube, it can lead to the expansion of the diaphragm.

Frequent breakage of the carburetor Stihl and how to avoid it

A common cause of failure of the carburetor on a Stihl chainsaw is the sticking of the valve in the nozzle. The reason for sticking is a violation of the storage of the chainsaw, more precisely the instructions of the manufacturer Stihl 180 for the 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 fire gasoline from the carburetor. Failure to comply with this elementary rule entails the following consequences. The foreskin valve, being in direct contact with the fuel, sticks to the body since gasoline gradually evaporates and only sticky oil remains. It is impossible to replace the nozzle since they are not in the repair kit, you can only try to knock it out and flush it, which is not always possible to do without damaging the nozzle.

Removal and installation algorithm.

In cases when it is necessary to clean the Stihl 180 carburetor or disassemble it, you will first need to remove the assembly from the chainsaw. It should be done in compliance with a specific algorithm of actions:

  1. Put the protective cover for the chainsaw on the tire.
  2. Remove the top cover of the chainsaw.
  3. Remove the two nuts securing the air filter and carburetor.
  4. Remove the air filter housing.
  5. Disconnect the cable from the engine control lever.
  6. Carefully remove the lever from the seat in the housing, at the same time disconnecting the thrust rod from it.
  7. Pull the carburetor towards you and disconnect the fuel supply as well as the throttle thrust.

To facilitate the dismantling, you can additionally unwind the rear handle and disconnect the throttle rod first from it, and then only from the carburetor. It may be necessary since without a certain experience, it is quite problematic to disconnect the thrust from the carburetor, and it is easier to disassemble the handle first.
To install the part in place, follow the reverse order of the algorithm.
When removing and installing the chainsaw engine control lever, it is worth being extremely careful, since the seat on the saw body is the weak link of the saw, and very often inexperienced users break it.

Disassembly Stihl 180 carburetor.

To blow, change the gasket or needle valve, the carburetor must be disassembled. To do this, unscrew the four screws on the cover of the compensator and one on the fuel pump.
Having opened the case, it is worth being extremely cautious, since when debris gets inside the carburetor, it will make its work impossible. The thickness of the channels in it, comparable to the thickness of the thread or even human hair.


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