How To Adjust The Carburetor On A Chainsaw – All The Secrets Of The Correct Settings.

Stable work at any speed, developed power, efficiency, the use of technical capabilities in the amount stipulated and laid by the manufacturer, and even the service life of the chainsaw. it all depends on its carburetor. In addition to the fact that this node also needs to be maintained in proper condition and serviced on time, it must also be adjusted appropriately. Setting up the carburetor of the chainsaw is not easy, but with an unhurried, thoughtful approach and strict adherence to the instructions, it is possible for almost anyone, and it should be carried out at the first signs of the need for this, regardless of whether the new saw is operated or used.

The need to adjust the fuel supply unit (in the future UFT, that is, the carburetor) is indicated by the following causes, symptoms, and malfunctions:

  • factory or own settings were knocked down due to loosening of the adjusting bolts and vibration, or in the process of unsuccessful attempts to adjust the carburetor to a new one;
  • the cover of the chassis cover is damaged;
  • the engine does not start or starts up with an effort, and then almost immediately stalls;
  • the saw does not work stably at idle or does not hold them at all;
  • excessive fuel consumption and too thick exhaust;
  • The spark plug electrodes are black (fed to the motor of the re-enriched mixture) or with a white coating (depleted);
  • chainsaw does not develop maximum speed or power;
  • the motor stalls during acceleration;
  • there is a strong vibration of the chainsaw;
  • due to irregularities in the operation of the air cleaning system, particles of debris got into the mechanism distributing the air-fuel mixture;
  • The piston group has significant wear. in this case, the regulation of TFC is used as a temporary measure to make the operation of the tool more stable.

Naturally, when the dirt gets into it, the fuel system needs to be flushed. by adjusting the carburetor, this problem cannot be solved. A worn piston needs a major overhaul. However, in these cases, too, perform the setting.

Chainsaw carburetor adjustment.

Adjusting the UFD may also be necessary even if the grade or quality of the fuel, atmospheric pressure, humidity, and ambient temperature, altitude above sea level (when the place of operation changes from a plain to a mountainous area, then due to air dilution, and vice versa).
Before adjusting the DFT, it is necessary to make sure that both filters (air and fuel) are clean. Besides, there should be no air leaks into the motor from the side (through the glands, the gasket under the UFD or its accelerator pump, or anywhere else). Otherwise, it will not be possible to adjust the carburetor.

Preparing to adjust the carburetor.

Three screws regulate practically any UFT:

  1. 1. Bolt of the main jet, denoted by “H” and used to set the maximum speed of the saw motor.
  2. 2. An idling nozzle bolt, denoted “L” and used to set low revs. That is, to regulate the idle.
  3. 3. Bolt adjustment idle, denoted by different manufacturers in different ways: “S”, “LA” (Stihl), “T” (Partner, Husqvarna).

Carburetors with fewer adjusting screws are also found. So manufacturers protect their products from non-professional intervention and at the same time try to simplify their configuration.
Before starting the adjustment, you should carefully study the instruction manual attached to the chainsaw, especially the part where the turning angles of the adjusting bolts are given. It is an essential condition that will allow tuning without going beyond the operating parameters of the engine correctly.

For safe regulation during its implementation should follow the rules:

  1. 1. The tool must be stably mounted on a flat surface of a rigidly fixed object (workbench, shelving, table).
  2. 2. The chain should be directed away from yourself and others present.
  3. 3. There must be a safe distance between the chain and any surrounding objects, ensuring the impossibility of their mutual contact.

In such cases, adjust the carburetor on the chainsaw as follows. First, start the tool and warm it up for 10 minutes.
Adjusting the TFC starts with determining the position of the tuning screw “L”, at which the idle speed will be highest. To do this, very slowly and smoothly turn this bolt one way, then the other. And so several times until the desired position is found. After that, set the “L” on 1 / 8–1 / 4 turn (the required value is indicated in the technical documentation on the tool) counterclockwise (after this referred to as PSCF).
Then we continue the regulation of idling with the screw “S” (“LA”, “T”):

  • If the chain after the manipulations with the bolt “L” is motionless, then it is necessary to rotate “S” (“LA”, “T”) smoothly clockwise (further PES) until it starts to move. Then we twist the “S” 1 / 8–1 / 4 turn back.
  • If the chain moves, rotate the “S” (“LA”, “T”) of the emergency response engine until it stops, and then we twist the “S” 1 / 8–1 / 4 turn in the same direction.

The engine should run evenly. And check it out as it accelerates. It is believed that the motor in the acceleration mode normally works, if, with a gentle press on the accelerator, the revolutions in a short time and without “dips” increase to their maximum value. If the engine works irregularly and/or badly accelerates, then it is necessary slightly. by a maximum of 1/8 of a whole revolution. to tuck the “L” of the emergency zone. After this, you must again make the above setting “S” (“LA”, “T”). Repeat these adjustments until the motor starts to work evenly and accelerate well.
Now check the setting of the adjusting bolt “H”. To do this, we accelerate the engine to maximum speed. Only for a long time to drive him like this without a load is impossible; you need to pause. We look at the exhaust and listen to the work of the motor. If too much of the muffler comes out, and blue smoke and the chain saw makes a lot of noise, then the carburetor makes an excessively rich mixture. Also, while the maximum speed of the power unit is lower than it should be, and even in it, the deposit will be formed. In this case, it is necessary to “H” slightly tweak the emergency state. Then again we check the engine and, if necessary, repeat the adjustment.
When the power saw makes a screaming sound, the engine is scorching, a crash and/or misfiring accompanies the exhaust is heard, that is, detonation is going on. the mixture is too poor, and the maximum engine speed is higher than it should be. It leads to overheating of the power unit, burning of the piston, rapid wear of the cylinder and burning out of the spark plug. In this case, it is necessary “H” 1/4 turn to turn the emergency response zone.
At the end of the adjustment, check the saw at idle.

With a properly regulated TFC, it should work like this:

  1. 1. The chain is fixed.
  2. 2. The sound of the engine is almost like a four-stroke.
  3. 3. Clicking on the accelerator leads to a quick set of maximum revolutions.

If these conditions are not fully met, use “S” (“LA”, “T”), as indicated above, or repeat the setting from the beginning.
It is the approximate setting. For accurate need tachometer. We do everything the same, turn the adjusting bolts, focusing on the readings of this device. It will allow you to accurately and, most likely, adjust the carburetor from the first time, having achieved, depending on the model of the tool for working with the tree, setting the idle speed to 2800–3300 rpm or more and maximum. 11000–15000 rpm. Which ones should be displayed, it is necessary to look at the technical documentation (operating instructions) for the saw.
After maintenance, such as disassembling and flushing or previous unsuccessful attempts to configure this node, it may be completely misaligned. So much so that the chainsaw won’t start at all.

In this case, it is necessary to configure the device of the engine power supply system in 2 stages, conventionally called:

  • base. with engine off;
  • final. produced on a warm engine.

At the first stage, the adjusting screws “L” and “H” slowly twist the POSP to the stop. You do not need to make great efforts and try to tighten them. Then we turn back both screws back. for many models of saws on one turn. And for some. 1.5 turns. There may be other installations. It should be clarified in the technical documentation on the chainsaw. Several models hint directly on the cover of their body near the adjusting screws.
It will perform the recommended factory default carburetor setting. In this case, the screw “S” (“LA”, “T”) in any case do not touch, unless of course it is not twisted. When he is already twisted, you will have to work with him. Slowly screw in the “S” of the emergency response system up to the stop.
Go to the final stage. We are trying to start the engine. If there were no manipulations with the “S” adjustment (“LA”, “T”) and “L” and “H” are installed exactly as recommended, then it should start.
If the “S” had to be turned on for the reasons indicated above, then the motor most likely will not start immediately. After each attempt, it will be necessary to tighten this screw 1/4 turn of the emergency system and try again to start the engine. In the end, he must earn.
Then we warm up the engine for 10 minutes. If after its start or in the process of warming up the motor is unstable or the chain has started to move, then it is necessary to slowly and carefully rotate the “S” (“LA”, “T”) of the emergency response zone. As soon as the engine starts to work steadily and/or the chain stops, we immediately stop the adjustment. If the motor stalls, then we turn this screw on 1 / 8–1 / 4 (see technical documentation) of the emergency management system.
In the process of heating, the idle speed may start to rise, then again, it will be necessary for the “S” (“LA”, “T”) to start slowly turning the PSUR until they are normal by ear. On the already warmed-up motor, we continue to adjust the power system node, as described in the previous chapter.
After running on saws, only fine tuning of the DCF is performed. For this, a tachometer and technical documentation for the sawing tool used is required. The fact is that the factory has already established almost optimal settings. Just for running the engine and lapping other moving parts of motorcycle saws, the carburetor is set up to prepare a little more enriched than the calculated optimum, air-fuel mixture. Due to this, the maximum frequency of revolutions is slightly lower than the structurally laid down by the manufacturer, and the motor is better lubricated. Due to this, the engine running in and the rest of the moving parts pass in a sparing mode.
Therefore, if there is no tachometer and/or reliable information (passport data) about the maximum speed and at idle, then you should not change the factory settings after running in since it will not work correctly. Anyway, in this case, it is not necessary to perform a fine adjustment. the chainsaw will work fine with the existing basic settings. And if you do it, it is better in the service center. Jewelry tuning of the carburetor is still a completely new tool recommended experts.
Before self-adjusting, it is strongly recommended to note as accurately as possible the previous position of the adjusting bolts. It will allow in case of an unsuccessful attempt to return them to their place. to the basic factory settings. The regulation starts with the bolt “H”. After setting the maximum speed, check idle. If they are different from normal ones, we first set them up using “L” and then “S” (“LA”, “T”). In doing so, we are guided by the rules and principles outlined in the second chapter of this article. But we turn the adjusting bolts, focusing on the readings of the tachometer. Then we continue to tune the carburetor, as indicated in the same chapter. Screws twist, following the indications of the tachometer.
Adjusting the carburetor chainsaw Stihl 180, 170 and other low-power is made by only one screw. “LD”. They expose idle speed.

The basic default setting is as follows:

  1. 1. Fully twist the “LD” of the PPS before it fits tightly.
  2. 2. Then turn it back POS on 2 turns.

If you need to make an additional or another adjustment, you first need to warm up the engine for 10 minutes.

Then, if:

  • Idle turns too low. we twist the “LD” of the emergency response system, until the chain begins to move, after which we turn this bolt 1/2 turn back;
  • the tool chain is moving at idle. slowly twist the “LD” of the emergency response engine until it stops, after which we turn this bolt another 1/2 turn in the same direction.

And it is better to tune with a tachometer, not forgetting that the chain at idle should not move. Maximum speed without load models Stihl 180 and 170. 13,500 rpm Idle. 2800 rpm
Adjust the carburetor chainsaw Stihl, equipped with a more powerful engine, produced in the same way as described in previous chapters. This also applies to such most popular models as Stihl 210, 230 and 250. For the basic setting (discussed in the third chapter), “L” and “H” are turned back on one turn after twisting. There are also saws with a carburetor, in which the basic setting “H” is 3/4 of a turn. By the way, this information is listed on the tool body cover.
The angle (pitch) of rotation of the adjusting bolts during UPT adjustment is 1/4 of a turn. Idle turns of models Stihl 210, 230 and 250. 2800 rpm, maximum without load. 13000 rpm.