How to adjust the carburetor on a STIHL 180 video

Saw won’t start

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

Fuel pump

A fuel pump is installed directly in the carburetor body, 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, it is she who is responsible for pumping fuel under the action of an impulse. A gasket is installed between the diaphragm and the body, which is responsible for the tightness of the fuel pump.

Advantages and disadvantages

Zama carburettors are very reliable and easy to operate. Specifically, a carburetor is installed on the STIHL 180 chainsaw, on which there are no screws for adjusting the quality and amount of the mixture, as we are used to. One screw greatly simplifies adjustment.

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

Despite the aforementioned advantages, the carburetor is sensitive to fuel quality. In addition to clean air from the air filter, the carburetor needs to be supplied with clean fuel from the gas tank. But this is not always possible, therefore, at least once every six months, it must be cleaned and blown through.

The saw has lost power, increased fuel consumption

Two very subjective indicators. In order to reliably state this or that, instrumental measurements are needed. From the practice of repair organizations, quite subjective things are often given out under one or the other. In some cases, blunt circuit effects can be mistaken for power loss. Naturally, performance in this case will be low. The saw sometimes seems to be quieter (blockages in cooling system, exhaust system). Increased fuel consumption may be due to fuel leaks.

Often the problem is in the muffler, not the carburetor.!

Adjusting the STIHL 180 carburetor

The carburetor of the STIHL 180 chainsaw, indiscriminately, can only be adjusted for the number of idle revolutions. It is impossible to increase or decrease the fuel supply in different modes using 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 with experience, it is possible to increase or decrease the fuel supply by increasing the clearance when opening the needle valve.

To increase the flow, the rocker arm of the needle valve in the distribution chamber must be bent up, and to decrease, down. This regulates the stroke of the needle and, accordingly, the throughput of the valve.

You should not carry out the adjustment yourself, since this must be done very accurately and in case of an error it is almost impossible to return the initial position of the rocker arm.

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The option of repairing and cleaning 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 to soak in acetone for several hours. Often, foreign objects and substances simply get into the nozzles and channels (sometimes, for example, traces of sealants are found there!). Therefore, simple cleaning has an excellent effect. No costs and no membrane changes. Although the decision to replace them must be made locally, guided by their condition.

adjust, carburetor, stihl, video

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

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

  • fuel pump (with internal diaphragm);
  • main (membrane) chamber;
  • diffuser;
  • throttle and air dampers;
  • needle valve;
  • fuel jets;
  • nozzle with valve;
  • idle speed adjusting 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 piston stroke, a vacuum is created in the engine crankcase. Due to this, the diaphragm in the fuel pump rises and the valve opens to supply fuel to the carburetor.

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

How to adjust carburetor of chainsaw STIHL MS 180

The vacuum generated in the carburetor diffuser by turning the air throttle valves is responsible for raising the control diaphragm. As soon as the engine starts, the mixture must 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 the idle nozzles (when the gas throttle is closed). There it is mixed with the intake air and the already prepared mixture enters the engine cylinder. A check valve prevents air from the diffuser from entering the main chamber.

STIHL 180 chainsaw carburetor: DIY adjustment, repair, device

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 in operation. The only component that requires close attention is the carburetor. This article will discuss carburetor adjustment, repair and maintenance.

Throttle flap

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 throughput of the channel and fuel from the carburetor cavity, rushes into the cylinder in a larger volume.

Combustion of a larger volume of fuel increases the amount of generated energy, which affects the power and speed of the processes. The damper is installed on the shaft passing through the entire carburetor body. At the exit of the shaft from the housing, a mount for the gas cable is installed, next to it is a cone-shaped adjusting screw responsible for adjusting the idle speed. By tightening the screw, you can slightly adjust the position of the shaft and the damper installed on it, thereby increasing or decreasing the idle speed, slightly opening or vice versa closing the damper.

adjust, carburetor, stihl, video

Malfunctions and repairs

The carburetor of the STIHL 180 chainsaw requires both initial and periodic adjustments. You can find out about its need by the following signs:

  • Engine problems such as not starting or stalling immediately after starting work. The most common reason is the use of a poor-quality fuel mixture.
  • Fuel consumption and increased emissions. Exhaust gases increase due to incomplete combustion of the fuel. Most often, this problem can arise due to oversaturation of fuel.
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Other breakdowns may occur, such as clogging due to damaged air filter or scale formation. The reasons may be related to the fact that gasoline remains in the fuel tank during a long idle period. This is due to the fact that the fuel is exhaled, which spoils the device.

Regardless of the reason, carburetor repair will be required, which most often comes down to adjustment. The method for performing this procedure depends on the model of the chainsaw, but you can adhere to general principles.

STIHL ms 180 carburetor repair

If, during the pressure on the gas, the chainsaw begins to stall, then the problem lies in the carburetor. Also, a sign of a malfunction of the carburetor will be a protracted start of the chainsaw and the impossibility of speeding up.

In most cases, such a malfunction appears during the wear of the rubber cuff, which is located on the piston of the fuel booster. During this, air is sucked in when starting the tool. Mostly such a breakdown appears after years of operation of the chainsaw.

The elimination of this malfunction is carried out in the following order:

  • Remove the carburetor. Unscrew the screw that holds the cover with the diaphragm. Turn the carburetor so that the pin is visible. It is necessary to remove the retaining ring from it and disconnect the air damper spring. Then the throttle valve. For this purpose, you need to unscrew the screw that holds it. Next, you need to remove the damper axis.
  • Pull out the accelerator with the spring. It has a cuff. The wear of this particular element leads to air leakage and engine stoppage after a recent start. The piston with the cuff must be replaced.
  • Assemble the carburetor in reverse order and install it on the chainsaw.

Now it is clear how to remove a frequent malfunction of the carburetor. Observing our client, the rules remain, you can simply do these works with your own hands.

What, in fact, how to repair the Partner 350 chainsaw is in charge of our next article.

If the tool does not start, then the discrepancy is hidden in the trigger mechanism differently in the ignition system. Then, if the starting device is working properly, then you need to painstakingly examine the candle. It must be turned out and painstakingly examined.

The cost of repair work and replacement of the carburetor

If there is no experience in repairing parts of a STIHL chainsaw, it is better to entrust it to specialists. The price depends on the complexity of the repair and the region. The average values ​​are as follows:

  • gasoline saw diagnostics. 300 rubles;
  • replacing the carburetor. 300 rubles;
  • comprehensive service (the complex includes flushing, installation and adjustment). 1000 rubles;
  • external cleaning indiscriminately. 300 rubles;
  • adjustment. 300 rubles;
  • bulkhead of the carburetor and engine. 2,000 rubles;
  • sealing the branch pipe. 200 rubles.

Regular carburetor tuning can improve the efficiency of your chainsaw and reduce fuel costs. In this case, it is recommended to strictly follow the technology or entrust the work to specialists.

Removal and installation algorithm

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

  • Put the protective cover for the chainsaw on the tire.
  • Remove the top cover of the chainsaw.
  • Remove the two nuts securing the air filter and carburetor.
  • Remove the air filter housing.
  • Disconnect the wire from the engine control lever.
  • Carefully remove the lever from the seat in the housing, at the same time disconnecting the air damper rod from it.
  • Pull the carburetor towards you and disconnect the fuel supply as well as the throttle rod.
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To facilitate dismantling, you can additionally untwist the rear handle and disconnect the throttle rod first from it, and then only from the carburetor. This may be required, since without some experience, disconnecting the rod from the carburetor is quite problematic 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, you should be extremely careful, since the seat on the saw body is the weak link of the saw, and very often inexperienced users break it.

Adjusting the carburetor of the STIHL 180 chainsaw

Usually, special screws are responsible for the quantity and quality of the 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 in such a way that the optimal amount of fuel enters the diffuser at all engine speeds. And here the LD screw is responsible for the adjustment, the rotation of which regulates the air supply to the idle jet. How does the engine speed change?

So, to adjust the carburetor of the STIHL 180 chainsaw, you need a regular flathead screwdriver and an electronic tachometer (optional). The adjustment algorithm is as follows:

  • Check the air filter. If necessary, replace the filter element.
  • Tighten the LD screw counterclockwise to the end, and then unscrew it 2 turns. Attention, the thread is left! To access the screw, a screwdriver hole is provided on the saw body. Start the engine and warm up for 5-7 minutes.
  • Turning the LD screw slowly clockwise, freely adjust the idle speed. 2 situations are possible:
  • The engine idle speed is very low. The engine does not keep idling. Turn the LD screw until the saw starts to rotate, and then turn the screw 1/2 back (the chain should stop).
  • The saw is spinning at idle speed. 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 manipulations with the carburetor settings, the chain continues to spin at idle speed, the saw must be returned to the dealer for a service center.

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

I would like to reiterate that STIHL carburettors, which are manufactured by its subsidiary Zama, are very reliable. With proper operation and storage, they are able to serve the entire period allotted to the chainsaw without repair.