Angle screwdriver for carburetor adjustment

Stihl 180 chainsaw carburetor adjustment

Usually, special screws are responsible for the quantity and quality of the fuel entering the diffuser, by adjusting which we change the section of the fuel channel. But on the used Stihl 180 chainsaw carburetor, 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 the LD screw is responsible for the adjustment here, 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 idle. 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, 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.

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.

Stihl 180 chainsaw carburetor repair

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

  • Gasoline does not flow into the carburetor. A commonplace reason is the failure of the fuel pump. The diaphragm has lost its elasticity or is leaky. This happens due to material fatigue with prolonged use. As a result, when the engine is under vacuum, the diaphragm does not rise and does not open the fuel channel with the valve. It can be replaced with a spare one from the repair kit by disassembling the carburetor.
  • 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 by replacing from the repair kit.
  • The carburetor is overflowing. It’s not hard to guess that the problem lies with the main camera. Dirt particles get into the cavity between the needle and the channel, i.e. the valve does not completely close the channel when needed and the chamber is flooded. Very often the membrane stops performing its function due to stretching (natural wear). As a result, when lowering, the diaphragm does not fully raise the needle, and fuel continues to flow. The main membrane is also included in the repair kit. Replacing it is not difficult.
  • Very often, after a winter standstill, owners of Stihl 180 chainsaws are faced with a difficult start. In this case, there is a sticking of the valve in the nozzle. The manufacturer recommends burning the remaining gasoline in the carburetor before storing the chainsaw. Gasoline tends to evaporate and during long storage, engine oil remains in the carburetor, upon contact with which the injector valve begins to stick to the body. As a result, no fuel flows into the diffuser. Since the nozzle is not part of the repair kit, you have to knock it out and rinse it thoroughly. This must be done very carefully.
  • If the idle jet or the nozzle is clogged, it is enough to blow them with compressed air. Or rinse in gasoline, in 90% of cases it helps. But you cannot use needles or wires, because 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 a retaining ring on the throttle shaft, as a result, it begins to wobble and play, which in turn leads to interruptions in operation.

screwdriver, carburetor, adjustment

So, you’ve decided to remove the carburetor and diagnose it. The withdrawal procedure is as follows:

  • Push the throttle trigger and lower the choke lever down. We turn the latch and remove the cover of the chainsaw.
  • We unscrew both fastening nuts with an 8 socket wrench and remove the air filter with the housing.
  • We remove the gas thrust (throttle valve) of the carburetor.
  • Disconnect the cable from the control lever
  • We take out the engine control lever from its place. Disconnect the air damper rod in parallel.
  • Pulling the carburetor towards you, remove it from the studs. Do not forget to disconnect the fuel supply hose.
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A more detailed and visual algorithm for dismantling the carburetor from the chainsaw is presented in the video.

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

After disassembly, the carburetor must be rinsed in gasoline, and the channels and nozzles must be blown out with compressed air. Under no circumstances should the carburetor be blown out under high pressure and in the assembled state. Otherwise, you can stretch the membrane or diaphragm. Carburetor stops working properly.

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

  • Unscrew the screw.
  • We assess the condition of the membranes, remove dust and dirt, and, if necessary, replace the membrane with a new one. Everything must be clean under the membrane The membrane must also be free of dirt
  • We check the condition of the filter mesh for dirt, if any, clean it.
  • Putting everything back and disassembling the carburetor from the other side. Having unscrewed 4 bolts, remove the cover, remove the membrane and assess the condition of the insides. In total, you need to unscrew 4 screws
  • To check the serviceability of the fuel supply by putting a hose on the fitting.
  • We blow into it with our mouth, while opening the needle valve with our fingers, everything should work clearly.
  • We blow out 2 holes in the nozzles with the same hose, they should puff out calmly, without excessive effort. If necessary, it is enough to clean it with a conventional cleaner WD-40.
  • Remove the jet-nozzle located on the right and clean it with a thin wire from the back side.
  • We clean and collect everything. When installing the cover, be sure to fit it correctly. 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 arm with an axle and a spring.

    What carburetor is used on the Stihl 180 chainsaw

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

    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 quantity of the mixture, as we are used to. One screw greatly simplifies adjustment.

    The membrane carburetor has no major 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, so at least once every six months it must be cleaned and blown.

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    How does the Stihl 180 carburetor work: device, principle of operation

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

    • 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.

    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. The check valve prevents air from the diffuser from entering the main chamber.

    How much does a new carburetor cost

    Chainsaws Stihl 180 are in great demand in Russia, primarily due to their reliability. The carburetor is no exception and is also quite reliable and unpretentious. Adjustment or repair of the carburetor is required only after long-term operation, not less than 5-7 years (with an average load). The tuning process itself is simplified as much as possible by Stihl engineers, this is the first chainsaw in which only one screw is provided for adjustment.

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    How to flush a chainsaw carburetor?

    You can clean the carburetor on a chainsaw using any aerosol cleaner. The best brands are Mannol, Hi-Gear and Nowax. These compounds well clean the walls and parts of the carburetor from accumulated dust, carbon deposits and hardened resin.

    Both the Chinese and German carburetor are washed in the same sequence.

    Cleaning the carburetor on a chainsaw is performed in this order:

    • First, you must drain the used fuel remaining in the fuel tank. Next, you need to unscrew the mount and remove the protective cover of the chainsaw body, and also remove the standard air filter;
    • Next, you need to remove the hose responsible for the fuel supply. To do this, you need to open the latches. After that, you need to unscrew the fasteners and remove the top cover of the factory assembly;
    • Next, you need to dismantle the cover with a blue gasket, which plays the role of a membrane of the fuel pump. Near the body there are staples in the form of springs. They will need to be removed, as well as unscrewed;
    • Then you need to unscrew the screw and carefully remove the needle valve. Directly below it is a built-in spring, which must also be removed. After that, you need to pull out the flap and the standard axle, gently pulling them along towards you;
    • After that, you will need to remove the drive lever, as well as the throttle flap and its factory axle;
    • All the removed parts of the chainsaw carburetor will need to be laid out on paper and checked for integrity. If necessary, worn out parts must be replaced;
    • Further, all dismantled parts must be rinsed with a spray can. Do the same with the float chamber and carburetor body.
    • After complete drying, all parts must be installed in the reverse order.

    After flushing, the carburetor will need to be installed in its original place in the chainsaw. Further, the garden tool will need to start and observe its operation at idle and maximum speed.

    How the carburetor is adjusted

    The algorithm for setting up the chainsaw is quite simple and consists of the following steps:

    • Adjusting the engine for smooth operation at low rpm.
    • Setting the carburetor for the correct supply of the fuel mixture at maximum speed.
    • Fine adjustment of the carburetor for idling.
    • Chainsaw check in all modes.

    Carburetor adjustment must be done after the engine has run a little and warms up.

    Now let’s look at how the correct adjustment of the chainsaw carburetor goes in more detail. Almost all carburetor models have three adjusting screws. The screw (T) is responsible for fine tuning in idle mode. Screw (H) setting for maximum speed. The screw (L) controls the mixture formation at low rpm. By tightening the screws (L) and (H), the fuel supply and the mixture becomes leaner, respectively, the speed increases.

    Chainsaw carburetor adjustment. what a beginner needs to know?

    Initially, all adjusting bolts are in the factory positions. this ensures that the optimal amount of fuel and air is sucked in. However, due to prolonged use of the saw in difficult conditions, the factory settings of its carburetor may be violated. Even a slight movement of one of the bolts by 1/5 of a turn will seriously damage the saw motor. In this regard, the operator must constantly monitor that the adjusting bolts are in the optimal positions set at the factory.

    If for some reason the work of the node has been disrupted, then it will need to be reconfigured. For this, 3 adjusting bolts are provided in the assembly device. The first of them is marked with the letter H. it is needed to tune the engine of the chainsaw when operating at maximum speed. The second screw marked L is used to adjust the motor when running at low rpm. The third screw can be labeled T, S or LA. Its task is to configure the internal combustion engine when operating in idle mode.

    Chainsaw carburetor tuning must be carried out with a completely serviceable engine. Immediately before adjustment, you will need to inspect the air filter, and, if necessary, clean or replace it.

    Weber DGAS 38. Part 1.Parts and Elements, replacements and disassembly, baselines

    Chainsaw carburetor device

    Most modern chainsaws are equipped with nearly the same carburetors. They practically do not differ from each other, and work on a similar principle. The only difference between cameras from different manufacturers is the material from which they are made. In expensive American, Swedish and German chainsaws, cameras are made of reliable alloys, on which protective coatings are applied. Cheap Chinese and Korean chainsaws are equipped with nodes made from cheap materials.

    Each carburetor consists of the following elements:

    • aluminum body with one-piece construction. Inside the body there is an inlet fitting, a main screw, an impulse channel, a bolt for adjusting the engine when idling;
    • throttle valve. it is responsible for adjusting the amount of air required to enrich the fuel mixture;
    • diffuser. located next to the chamber inlet;
    • sprayer. designed to supply the fuel mixture directly to the carburetor chamber;
    • float chamber. there is a float in it, which is triggered in the event of an insufficient amount of fuel;
    • nozzles. are valves that are responsible for adjusting the amount of fuel.
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    This chain saw carburetor circuit is as simple and effective as possible. In some models of gardening tools, it can be supplemented with additional pipes, oil seals or filters.

    The principle of operation of a chainsaw carburetor is quite simple. At the moment the engine starts, the air damper located at the bottom of the housing opens. In this case, a vacuum is formed in the float and air chambers, caused by the movement of the piston. As a result, the standard diffuser is triggered, which begins to suck in air. The amount of intake air depends on the opening of the damper. When the piston is triggered, fuel begins to flow into the chamber through the inlet fitting. Its quantity and flow rate depend on the position of the nozzles.

    Subsequently, the fuel in the air chamber begins to mix with air. After that, the finished air-fuel mixture passes through the intake valves, from where it is sent to the combustion chamber of the saw engine.

    What to do if gasoline does not flow into the chainsaw carburetor?

    The first of the reasons for this breakdown is the clogging of the fuel filter with dust and dirt. This happens due to the presence of a large amount of harmful impurities in gasoline and used engine oil. Over time, they accumulate on the surface of the filter, due to which the filter loses its ability to pass fuel. To solve the problem, you will need to thoroughly clean the filter by rinsing it in a bath with a cleaning agent. If the filter has holes or other signs of wear, it must be replaced immediately.

    The second cause of breakdown is contamination or breakage of the tube through which fuel is supplied to the carburetor. If the hose is not cut off, it will be enough to thoroughly blow it out with compressed air from an aerosol for cleaning. If the tube is broken, it will need to be replaced. When installing the hose, the places of its joints with the fittings must be carefully treated with a sealant.

    There is another malfunction that occurs much less frequently than the previous two. It consists in a breakdown of the valve that regulates the rate of fuel supply to the carburetor. If dust or small chips get inside its mechanism, then the flap is blocked and remains in the closed position. Repair of the assembly can only be performed with the replacement of the damper, since it, most often, cannot be restored.

    How to properly adjust the carburetor on a chainsaw?

    Place the tool on a firm, level surface to set up the assembly. It is best to adjust the carburetor of the chainsaw in a place protected from dust and moisture.

    The node setup process should look like this:
    • First you need to unscrew the fastening bolts and remove the protective saw body. This will make it possible to inspect the carburetor and, if necessary, clean it;
    • Next, you need to remove the standard air filter of the tool. If the saw is equipped with an additional foam insert, then it must also be removed;
    • After that, you need a screwdriver, which you need to tighten the bolts marked H and L clockwise until they stop. This must be done very carefully so as not to break the bolts;
    • Then both screws should be unscrewed 1.5 turns in the opposite direction;
    • Next, you need to start the chainsaw engine and let it run for about 7 minutes;
    • As soon as the engine cylinder heats up, you will need to start turning the bolt L until the internal combustion engine starts working at maximum speed. Immediately thereafter, the bolt must be turned 1/4 turn in the opposite direction;
    • Then you need to adjust the operation of the motor at high speeds. To do this, you need to connect an electronic tachometer to the engine, and start turning the bolt H until the readings on the instrument panel coincide with the instructions for the recommended maximum revolutions in the instructions for the saw;
    • In the end, it remains to adjust the operation of the internal combustion engine of the saw at idle. To do this, slowly turn the bolt T against the clock hand until the motor runs stably and without dips. If the engine starts to stall, then the T bolt should be turned in the direction of the clock hand.

    To adjust the carburetor on a chainsaw, you should work as accurately as possible with the adjusting bolts. Excessive tightening of the screws will lead to increased stress on the engine and other important parts of the garden tool.

    Chainsaw carburetor

    The chainsaw carburetor is the element that mixes the air / fuel mixture. Not only the stability of the engine, but also the speed of the entire chainsaw depends on the condition and serviceability of this important unit. In this regard, each owner of a garden tool should study the design of the carburetor, as well as familiarize himself with the rules for its maintenance and repair.