How to idle a chainsaw

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.

How to idle your STIHL chainsaw

Chainsaws STIHL ms 180 are designed in such a way as to make them as easy as possible for inexperienced users. To this end, some of the settings available on the more powerful STIHL models have been removed from the saw carburetor. But there is still an opportunity to adjust, and repairs, as well as adjusting the carburetor of the STIHL 180 chainsaw with your own hands, is possible.

idle, chainsaw

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.

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.

How to adjust the carburetor STIHL ms 180 what is the min and max rpm? Also a similar video about the adjustment on my channel: https.

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.

Chainsaw STIHL. The idle stop bolt “la” must first adjust the idle speed on the chainsaw. Correct adjustment of the screw for the accuracy of the idle values ​​on the chainsaw. Idle setting. Adjusting the carburetor on a STIHL chainsaw. Repairs. Idling setting. With your own hands. What sellers are silent about.

Saw repair after 10 tanks. What sellers are silent about.

For further fine adjustment, you need a tachometer and it is better to entrust it to specialists., especially since in most cases it may not be needed.

Start the tool setting with screw L, then use screw H and finally screw T (LA).

How To Tune A Chainsaw | Adjusting The Carburetor

We find the highest idle speed, for this we slowly turn the screw L in different directions. After finding the position of the highest engine speed, turn the screw L 1/4 turn counterclockwise. Adjusting how to adjust the carburetor on a STIHL chainsaw chainsaw ms. If the chain rotates at idle speed, the screw T should be turned clockwise until it stops.

The H screw adjusts the power and speed. Adjusting the carburetor to a lean mixture leads to excessive speed, engine overheating and failure of the piston chainsaw.

Warm up the chainsaw engine at idle speed for at least 10 seconds and turn the screw H 1/4 turn counterclockwise. Let the engine run for about 10 seconds, then check the maximum engine speed with a tachometer. On STIHL chainsaws 180 ms idle speed adjustment. On this chainsaw? If the maximum speed does not correspond to the passport one, the operation should be repeated. When the mixture is too rich, the muffler starts to smoke, when the saw is too lean, it squeals and overheats.

We finish the adjustment by adjusting the idle speed, as already described above. The idle speed is set correctly if the engine runs smoothly at minimum speed and the chain does not rotate.

The carburetor can be considered adjusted if the engine accelerates quickly and sounds like a four-stroke at full throttle.

Carburetor Sthil MS180 (STIHL 180). Adjustment. no, I have not heard

On STIHL MC 180 chainsaws produced at the moment and in the last short period of time, Chinese-made carburetors have been installed, which have only one adjustment screw. Such membrane-type carburetors are actually not intended for disassembly, since it is all sealed and filled. So to say: “Adjustment. no, I have not heard” In this case, it is easier to purchase a carburetor for a STIHL 180 chainsaw.At the same time, carburetors are sold as unique (also made in China, but at a plant owned by STIHL) and from other (also Chinese) manufacturers.

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Why does my chain keep spinning at idle? How to fix it and how it works. ��

It should be noted that not looking at the Chinese creation, the unique STIHL 180 carburetors are very reliable and occasionally let the owners down then the unique 2500 rubles, in other words, almost 4 times more expensive.

For chainsaws produced for 5 and more years, repair kits can be purchased.

When to adjust the carburetor?

There are several signs that help you understand that you need to adjust the carburetor on your chainsaw, these signs are listed below:

  • The factory settings of the chainsaw were changed due to the weakening of the carburetor adjusting bolt;
  • The cover of the UPT case is damaged;
  • The engine starts poorly or does not start at all;
  • the chainsaw does not keep idling or is unstable at idle;
  • the exhaust of the chainsaw is too thick;
  • excessive consumption of fuel;
  • spark plugs quickly turn black or become covered with a white coating;
  • the chainsaw does not gain the declared power characteristics;
  • during a set of revolutions, the chainsaw engine stalls;
  • the chainsaw vibrates strongly at idle;

Of course, these reasons can be caused by other problems with your chainsaw, and in order to eliminate unnecessary things, you need to take a number of measures. If dirt gets into the fuel system, then the engine can also jump at idle and in this case you just need to flush it. If your piston group is worn out, then power is lost, but in this case, when idling, you will hear a characteristic knock. you need to change the piston group.

Same. you will need to adjust the carburetor if you start using a different fuel, or use the chainsaw in other atmospheric conditions.

Operating principle

The purpose of the carburetor is to prepare the working mixture for feeding it into the engine cylinders. This mixture is gasoline and air in the proportions necessary for the engine to work. If this ratio is violated, then the engine will not work clearly. When the mixture has a lot of gasoline, then in unprofessional terminology it is called saturated, and if, on the contrary, there is little, then it is poor. But in any case, a failure in the proportions of the working mixture will have a bad effect on performance.

Different models of chainsaws may have different carburetor designs, but they are all identical in principle. The air moves through a special channel at a speed that can be adjusted by closing or opening the damper. Gasoline, in turn, enters the carburetor through the jets and mixes there with air, creating a special mixture that enters the engine.

The pressure in the float compartment of the carburetor, where the gasoline is before mixing, is close to atmospheric pressure. When you open the damper, the air becomes more, as well as gasoline, due to which the engine speed increases. In this case, a vacuum is created in the air channel and gasoline is drawn into the air stream. This is how the carburetor works.

In order for the chainsaw to work smoothly and efficiently, and also at the same time there was no high fuel consumption, its carburetor must be adjusted accordingly. Before such work, you must first check the air and gasoline filter. If dirt is found on them, then they should be replaced.

Chainsaw tuning for most models, as a rule, is carried out using three screws. high and low speed and idle.

The following signs should indicate the correct setting:

Chainsaw Attitude/Idle Adjustment

  • The chain must not move when idling.
  • Motor runs smoothly.
  • At the start, there should also be no breaks in the work.

Do-it-yourself chainsaw carburetor repair should be done very carefully, because any mistake made can lead to serious consequences, even before the engine is completely damaged. If you do not have enough experience, then it is better to seek the help of a specialist.

The main stage

The engine turns on at medium speed and warms up for about 10 minutes. The idle speed screw must move clockwise. It is released only when the engine comes into stable operation. It is necessary to check that the chain does not move during this process.

In idle mode, the engine may stall (the reason is here). In this case, immediately turn the adjusting screw clockwise until it stops. Sometimes the chain starts to move. In this case, turn the adjusting screw in the opposite direction.

Dismantling the carburetor if it is necessary to check or repair components

The device of different models of carburetors is almost the same, so when working with them, you can use the standard scheme. All elements must be removed carefully, and then laid out in the order below, so that you can successfully place the items in place at the end of the repair work.

  • The top cover is removed. To do this, unscrew the 3 bolts holding it in a circle.
  • The foam is also removable, as it is the upper part of the filter that conducts air.
  • The fuel hose is removed.
  • The drive thrust is output directly to it.
  • The cable end is detached.
  • The petrol hose can be completely removed by systematically pulling it off the fitting.

To finally prepare the carburetor for overhaul or replacement of the smallest parts, you need to carefully disconnect it from the main system. Sometimes further disassembly is required. Unscrew the components carefully and fold the fasteners in groups, as these small parts are easily lost.

Adjusting the carburetor of a Chinese chainsaw

Carburetors installed on Chinese-made saws are made similar to European ones and have the same adjustment screws.

The carburetor of a Chinese chainsaw is adjusted according to the algorithm presented above, and differs in that when initially adjusting the screws (L) and (H), they must be turned out two turns. Further, the carburetors of the Chinese saw are adjusted in the same way as the European ones.

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Process description

If the carburetor of the chainsaw is not adjusted and it is not possible to start the chainsaw, then the adjustment begins by setting the screws (L) and (H) to the standard setting. This is 1/5 of a turn of the screws until they are fully tightened. After that, you need to start the engine, let it run a little and warm up. The next step is to set up the low speed mode. Optimum low engine performance can be achieved by adjusting the screw (L) and idle speed (T). To do this, first the screw (L) is tightened until the maximum engine speed is obtained, then it is released by 1/4, and the idle speed is normalized with the screw (T).

After adjusting the work on the “bottom”, the thrust and maximum engine speed are adjusted. To do this, slowly tighten the screw (H) and check the speed according to the readings of the electronic tachometer.

exceeding the maximum engine speed declared by the manufacturer is unacceptable.

An important step is to check the saw in all operating modes after adjusting it, for this you need to let the chainsaw cool down, and then start it according to the cold tool start algorithm. If the saw starts up normally and idles smoothly, you need to check how it cuts. If in the process of checking deficiencies in the power of the chainsaw are found, then it is necessary to repeat the adjustment of the screw (H) by unscrewing it and checking the thrust in operation.

loss of thrust at maximum rpm recommended by the manufacturer is an indicator of CPG wear or poor fuel quality.

Husqvarna Saw Carburetor Adjustment.

For the break-in mode, so that the parts receive sufficient lubrication, the carburetor setting of the Husqvarna chainsaw is made so that the maximum speed is 600-700 rpm. below working. If it is not possible to set the operating maximum frequency by the tachometer, you should not change the presets with the H screw. It is forbidden to exceed the value of the maximum number of revolutions by the manufacturer. If, after completing the adjustment, the saw chain moves when the engine is idling, turn the screw T counterclockwise to bring it to a complete stop.

For accurate adjustment, the saw must be warmed up for at least 10 minutes, set on a flat surface. The tire should point away from the person making the tune. At the initial stage, the highest idle frequency should be found. To do this, screw L is smoothly turned first from left to right, then vice versa. When the maximum revolutions are found empirically, screw L should be unscrewed counterclockwise by a value from 1/8 to a quarter of a full revolution.

Idling is adjusted by the nozzle marked with the letter T. It must be turned from left to right until the chain starts to move. Then gently feed in the opposite direction until the rotation of the chain stops. The screw H is considered to be installed correctly if the noise of the saw at full throttle without load remains low. If the exhaust is too smoky and the saw makes a lot of noise, the mixture is too rich. It is necessary to turn the H jet clockwise until the correct sound is set. How to properly tune the carburetor, you can watch the video below.

Chainsaws Partner and STIHL, their adjustments.

In STIHL and Partner chainsaws, the proportion of air and gasoline in the mixture is set with adjusting screws H and L. When the screws are loosened, the mixture is enriched, the revolutions increase. Screwing in leads to a leaner mixture and, accordingly, a decrease in engine speed.

Setting the carburetor of the partner’s chainsaw to idle is carried out with the T screw (STIHL marks this adjustment with the letters LA). Basic tool setting is done in the factory during final testing. In most cases, the carburetor is adjusted to deliver a slightly richer air-fuel mixture than the optimal design. The factory settings must be saved during the first few hours of operation, during the running-in period. After that, a finer adjustment can be carried out, although this is not necessary, the saw will work normally on the basic settings.

For fine adjustment of the carburetor, a tachometer is required, in addition, technical documentation will be required in order to carry out work in strict accordance with the manufacturer’s requirements. The best solution would be to entrust the jewelry tuning of the fuel equipment to specialists.

If, nevertheless, it is decided to adjust independently, you should start with the L screw, then go to the H nozzle, and then set the idle speed by turning the T screw (or LA. if it is a STIHL saw).

By smoothly turning the screw L in both directions, a position is sought at which the idle speed will be maximum. After this point is found, it is required to unscrew the screw L by 1/4 turn. If the chain continues to move when the engine is idling, the T (LA) screw is slowly unscrewed until the chain stops.

After setting the maximum speed with the screw H, the value of their frequency is checked by the tachometer. If the speed at maximum does not correspond to the values ​​indicated in the documentation, the adjustments are repeated. If the mixture turns out to be too rich at maximum speed, too much smoke comes out of the muffler, when the mixture is poor, the saw makes a squealing sound and the engine heats up unnecessarily. The adjustment ends by setting the idle speed. the position is considered correct if the engine runs exactly at the minimum speed and the chain is at a standstill. The idle speed setting can be viewed in the video below.

Adjustment principles

Turning the adjusting screws L and H changes the throughput of the air ducts. By tightening these screws, we reduce the amount of air, respectively, the amount of fuel entering the cylinder increases, this process is called enrichment (a mixture rich in fuel).

By unscrewing the screws, we increase the amount of air, deplete the mixture. The two-stroke engine is very sensitive to the quality of the air / fuel mixture. If there is a lot of air, the revolutions increase, but the thrust becomes lower. If there is not enough air, then the engine does not develop speed and full power, this is called swelling.

Standard screw position

You need to start the adjustment by setting the screws L and H to the standard position, then in which the tool can be wound. Typically, this is 1.5 to 2 turns of each screw. The T screw is tightened halfway.

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Do-it-yourself chainsaw carburetor adjustment

A chainsaw is a tool that will come in handy in any summer cottage, even for amateurs, not to mention professional workers. But, like any other device, a chainsaw needs constant care and prevention. One of the most common procedures is adjusting the carburetor of a chainsaw due to a past misalignment.

Adjusting your Husqvarna chainsaw

During the break-in period of the Husqvarna 142, 240, 236, 137 chainsaw and other similar models, the carburetor settings are set in such a way that the engine speed is 600-700 less than normal working ones. In the event that the operating frequency cannot be adjusted by the tachometer, it is not recommended to knock down the factory settings with the H screw.

The manufacturer expressly prohibits exceeding the working number of revolutions independently. When, after adjusting the carburetor, the chainsaw chain moves at idle, then by turning the screw T counterclockwise, you need to stop it.

In order to adjust the saw accurately, it must be placed on a flat surface with the bar forward. You also need to warm up the engine for at least 12-15 minutes. The highest idle frequency number should be determined first. To do this, screw L must be turned clockwise in the chainsaw, and then in the opposite direction. After determining the desired frequency, the same screw is turned counterclockwise from 12 to 25% of its full turn.

Idle speed in the models of this manufacturer is adjusted using a jet with the letter T. Adjustment is made by turning it clockwise until the chain moves. Then turn lightly counterclockwise until the chain stops moving.

The screw H of the chainsaw is adjusted correctly only when the saw does not make a lot of noise when the gas is pressed all the way, and at the same time it does not become heavier with any load.

In the event that the saw is too noisy during operation and smokes, then this jet must be turned from left to right to adjust.

Chainsaw carburetor device

To independently adjust the carburetor of a chainsaw, you do not need to be a professional motor technician. However, you still have to memorize some aspects of the carburetor’s operation regarding the process of preparing the fuel mixture.

The vast majority of chainsaws are equipped with Chinese-made Walbro carburetors. In their structure, they are simple, if not primitive. There is a monoblock body of the straight-through type with a through hole. A diffuser is located inside the hole. a narrowing of the passage with the fuel injection channel. There are dampers on both sides: the smaller one is the throttle one, it regulates the amount of the fuel mixture to be supplied to the cylinder. A larger damper. air, serves to limit the air flow during a cold start.

Walbro carburetor device: 1. fuel inlet fitting; 2. impulse channel of the membrane pump; 3. inlet valve; 4. membrane of the fuel pump; 5. exhaust valve; 6. filter mesh; 7. air damper; 8. throttle valve; 9. fuel channel; 10. idle speed adjustment screw; 11. needle; 12. idle nozzles; 13. control membrane; 14. fuel chamber; 15. main jet; 16. diffuser; 17. the main adjusting screw

All the magic of fuel preparation takes place in the covert channels and the diaphragm pump chamber. When the throttle valve is turned, the cross section of the channel through which fuel is injected into the mixing chamber increases slightly and the fuel enters in a larger volume. In this case, the carburetor has two kind of valves: for feeding at low and high speeds. When changing the position of the throttle valve, the fuel flow changes proportionally between the two valves.

The need for such a device is that at idle and under load, the quality of the mixture should be different. In this case, the channel through which the fuel is supplied to the mixer at idle speed does not completely overlap when the engine accelerates and vice versa. the maximum speed channel is slightly undercut at idle speed.

Saws STIHL & Partner

In STIHL 250, 361 and Partner 351, 350 chainsaws, the carburetor is adjusted using the H and L screws by setting the proportions of gasoline and air. If you release them, a large part of the fuel will be added and therefore the revolutions will be high, otherwise, on the contrary, they will fall.

Idling speed in Partner chainsaws is regulated with a screw with the letter T, and in Calm, as a rule, you need to look for the aircraft marking. The standard setting of the chainsaw is carried out during the final tests. Basically, after such settings, the percentage of fuel in the working mixture is greater than that of air, which does not correspond to the optimal parameters. But they must be saved during the first hours of operation during the running-in of the device. After that, the saw can be adjusted independently, but it will work well at the factory settings.

But if it is decided to regulate independently, then the actions must be performed in the following sequence:

  • screw adjustment L;
  • then adjust the H jet;
  • after that, go to the idle speed setting using the T screw (if the STIHL chainsaw is LA).

First, screw L must be turned in both directions in order to find the maximum engine speed. If that point is found, then turn the same screw by ¼, thereby slightly slowing down the speed. If at the same time the chain continues to move at idle, it is necessary to immediately turn the screw T (LA) until the chain stops completely.

After setting the maximum speed with screw H, you need to check the frequency with the tachometer. In the event that it does not correspond to those indicated in the service book, the setting must be repeated. When a lot of smoke comes out of the exhaust pipe at maximum speed, then the mixture is too rich in fuel, if noises are heard and the engine is very hot, then on the contrary, it is poor. Then you need to adjust the idle speed. With the correct setting, the engine should sound even at low speeds, while the chain should not move.