Carburetor Adjustment Stihl 180 Chainsaw

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.

Carburetor Adjustment Stihl 180 Chainsaw

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.


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. Thereby, 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 ask how it 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.

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 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.


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.