How to Use a Tachometer For a Chainsaw

Carburetor adjustment Husqvarna 372 XP, 365

Adjusting the carburetor of the Husqvarna 372 XP chainsaw involves adjusting the engine to local criteria, such as climate, altitude, gasoline quality and type of oil for 2-stroke engines.

The carburetor is equipped with 3 regulation abilities:

L = Low speed jet.
H = High speed jet.
T = Screw for idle adjustment.

The nozzles L and H control the amount of fuel so that it corresponds to a clot of air supplied by the throttle of the gas handle.

If the jets are screwed in clockwise, the mixture will be poor (less fuel in relation to the amount of air), and when unscrewing the jets counterclockwise, the mixture will be richer.

A poor mixture gives higher revs, and a richer mixture. lower revs. How is the Husqvarna 142 carburetor adjusted? Screw T adjusts the position of the shutter at idle.

If the screw T is turned clockwise, the number of idle turns will increase, and if the screw is turned counterclockwise, number of revolutions will decline.

Preliminary adjustment and running-in of the Husqvarna 365 XP chainsaw

When checking the work at the factory, a preliminary adjustment of the carburetor was performed. Preparatory adjustment: N = 1 revolution, respectively L = 1 revolution.

So that the details of the Husqvarna saw motor receive sufficient lubrication (break-in), the carburetor is set to slightly overcharge the fuel consistency for the first 3-4 hours of operation.

For such an installation, the largest number of revolutions is set at 6-700 rpm below the recommended one.

If there is no ability to check the highest number of revolutions with a tachometer, then jet N must not be installed on the fuel mixture below the preparatory unit.

It is forbidden to exceed the highest number of revolutions. Adjusting the carburetor on a Husqvarna chainsaw is the main setting for a chainsaw. If the chain of the chainsaw rotates at idle, then by turning the screw T counterclockwise, it is necessary to achieve its complete stop.

Fine adjustment of the carburetor of the Husqvarna 365, 372 XP chainsaw

Page 29: Fine-tuning, Conditions, Low-speed adjustment screw l, Fine-tuning of idle speed t, Low-speed needle screw n, Maintenance, Low-speed adjustment screw

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how to use a tachometer for a chainsaw

Work, pre-adjustment,

ATTENTION! Do not start saw without assembly
saw blade, chain, and clutch cover
(chain brakes). Otherwise it may
clutch flapping occurs that
will cause serious injury.

Carburetor controls engine speed with

throttle body. In the carburetor formed air
fuel mixture, the composition of which can be regulated. For
maximize saw performance

carburetor must be properly adjusted.

Carburettor adjustment means engine tuning for

work in certain conditions, such as climate, altitude

sea ​​level, gasoline and oil used in the fuel mixture
for two stroke engines

carburetor has three

possible areas

L = low speed jet.
H = high speed jet.

T = idle adjustment screw
throttle stroke.

Required air quality

heating mixture, depending on the air flow regulated
throttle, adjustable by turning the screws

fuel feed L and H. If turned clockwise

(screw), then the quality of the working mixture (air /

fuel) is leaner (less fuel), and if you turn them

counterclockwise (unscrew), then the quality of the working mixture

enriched (more fuel). The impoverishment of the working mixture gives

increase in engine speed, and enrichment. decrease.

Screw T adjusts idle speed. Adjusting position

throttle it increases or decreases feed

air, dining or enriching working mixture. Turn T screw
clockwise increases idle speed, turn against
clockwise reduces idling.

Setting basic parameters and running in

Basic carburetor adjustment is done at the factory.
manufacturer during the chainsaw test.
The following basic
setting: H = 1 revolution, respectively L = 1 revolution.

To ensure proper lubrication of the engine mechanisms (during

break-in time) carburetor during the first 3-4 working hours

should be adjusted to a richer working mixture. For
To ensure this mode, you need to adjust the screw

maximum speed 6. 700 rpm below recommended
at maximum mode (full throttle without load).
If you cannot check the revolutions with a tachometer, then the screw
adjustment H should be turned towards the enrichment of the working

mixtures relative to the established preliminary position.

Do not exceed recommended maximum speeds. it
leads to overheating and damage to the saw engine.

After "running in" chainsaws need to be accurate

Fine adjustment should

performed by a specialist. First you need to configure

nozzle L, then idle screw T and then nozzle H.

Engine rpm:

Maximum revolutions Idle revolutions

Before adjusting the carburetor, clean the air

filter and install the cylinder cover. Carb adjustment with

contaminated air filter will cause after
cleaning the working mixture will be depleted. This can lead to
serious engine damage.

Gently turn the L and H jets clockwise until

failure. Now turn them one turn counterclockwise
arrows. The carburetor is now set to H = 1 and L = 1.

Now start the saw in accordance with the start instructions

and let it warm up for 10 minutes.

the chain is idling, then turning the screw
T counterclockwise you need to get it full

Put the chainsaw on a flat surface with a saw

the blade away from itself so that the saw blade and chain do not
touched the surface or any objects.

Low speed adjustment screw

idle turn

L clockwise or

accordingly counterclockwise
arrows. When will

idle speed

counterclockwise rotation
arrows. NOTE! If

chain idles, turn idle screw

counterclockwise until the saw stops.

Precise setting of idle speed T

Adjust the idle speed with screw T. Then
turn it counterclockwise until the chain stops. At
to reconfigure, first turn screw T clockwise

arrow before starting to rotate the saw chain. When correct
regulated idle, the engine starts to run

smoothly from any position. In addition, there should be a clear
threshold value of revolutions at the moment of the beginning of chain rotation.

if idle speed is not
adjustable until the circuit stops
Contact your dealer. Not
use the chainsaw until it is
properly configured or repaired.

Low Speed ​​Needle Screw N

Screw adjustment high

revolutions N affects

saw power. Customization
high speed propeller N

mixture too lean (screw H
too tightly closed)

causes increased speed
and disables the engine.

Give the saw a job
thaw at full speed about

10 seconds and pay attention

Video: How to Use a Tachometer For a Chainsaw

ny on the sound of work. Then

release gas and turn the screw

N 1/4 turn counterclockwise.

Let the saw run again at full speed for about 10

seconds and notice the change in sound work

engine. Turning screw H another 1/4 turn counterclockwise

arrows, repeat the procedure. So, the saw is checked in
the following positions: H = ± 0, H = 1/4, H = 1/2 relative

starting position. At each position (at full

revolutions) the engine worked with a different sound. Screw high
revolutions N is set correctly if the saw is slightly "foursome". If

the saw is whistling, the mixture is too poor. If you drank heavily

A chainsaw is a great helper for any man living in his house. The chainsaw device is a complex system that needs careful maintenance and requires increased attention. Today you will learn how to adjust the carburetor of the Husqvarna 137 chainsaw with your own hands in the garage?

When is carburetor adjustment necessary?

The reasons that will require adjustment of this unit can be listed for a very long time.

Among the main malfunctions, the following can be distinguished:

  • The increase in idle speed;
  • The appearance of a large amount of smoke during operation;
  • Deterioration of starting properties;
  • Insufficient tool power when cutting.

Here is a far from complete list of all known faults. Sometimes a procedure such as adjusting the carburetor on a Husqvarna chainsaw needs to be performed after a major overhaul of the power plant or after maintenance.

The developers of Husqvarna 137 write in the passport that carburetor adjustment must be carried out before and after the tool break-in.

How does a carburetor work on a Husqvarna 137 chainsaw?

On chainsaws of these models, the Walbro carburetor is most often installed from the factory. Before you adjust the Walbro carburetor on a Husqvarna chainsaw, you need to have a minimal understanding of its device and know the principle of operation.

What is responsible for the supply of a mixture of fuel and oil

For an accurate supply of fuel with oil, the fuel pump is used, which is driven mechanically from the crankshaft. The carburetor itself is equipped with a diaphragm and a special needle valve, which are responsible for regulating the pressure in the system. Thanks to them, the organization of the correct operation of the metering chambers and the pump occurs, which improves the operation of the chainsaw.

Fuel mixture

When operating a chainsaw, a fuel mixture of gasoline and oil in a ratio of 15: 1 by volume should be used, i.e. 1 liter of oil should be added to 15 liters of gasoline and mix thoroughly. The amount of gasoline and oil in the fuel mixture is shown in this table:

ATTENTION! Application of oils: “Lukony-2T; TNK-2T OIL: AZMOL Sport 2T GD ”, etc., and used oil in the fuel mixture will lead to failure of the connecting rod needle bearing.

What is responsible for the air supply

Two air dampers installed on the diffuser chamber are responsible for the air supply. The first can regulate the amount of air at the moment of pressing the accelerator and is called the throttle, and the second provides a restriction of air supply at the moment when the chainsaw is cold-started. To facilitate starting, the shutter is closed, which means that the mixture becomes rich, as it is saturated with a large amount of fuel. It is easier to work in this mode, but since it increases fuel consumption, this mode is not applied throughout the entire operation. The saw works for wear.

To spray fuel into the cylinders, a nozzle with a check valve is used.

The principle of operation is simple: it limits the return of the mixture back to the chamber. All the main malfunctions of chainsaws, most often, occur when the mechanism does not work properly.

  1. The most common mistake is storing the tool for too long. The fact is that with prolonged inactivity the valve sticks and either fills the cylinder with fuel or simply does not open.
  2. The second problem is the increase in the amount of air in the mixture, caused by suction from the outside when the valve is not working properly. It is no longer possible to adjust here, since in this case only valve repair or replacement helps, since the saw will not respond to the adjusting screws.

Unlike a car, setting up the carburetor of the chainsaw provides three adjusting screws that are responsible for the quality of the mixture, the number and nominal speed of the crankshaft of the Husqvarna engine:

  • screw L. designed to adjust the number of revolutions during operation in medium modes and adjusts low revolutions;
  • Screw N. adjusts the number of high revolutions and the thrust of the installation;
  • T. is designed to adjust the total amount of fuel and adjusts the operation of the throttle assembly.

It is not recommended to touch the first two screws without special skills. The problem is that if you configure them incorrectly, the carburetor will not be able to start the engine, or even start it in the wrong operating modes. Such adjustment of the screw can lead to its speedy wear and failure. This principle is embedded in many devices.

Settings are not listed in any table. Therefore, you should not look for this data in the specialized literature, but just clearly follow the instructions. The table in the passport has only informational value regarding the characteristics of the engine.

What will I need to adjust the Husqvarna carburetor with my own hands?

In order to correctly adjust the carburetor of the chainsaw, you must first stock up with the appropriate tool.

You will need the following list:

  • The most common screwdriver with which to loosen or tighten the adjusting screws;
  • A tachometer designed to calculate the speed of the crankshaft. It is necessary to adjust the idle speed, since it is rather problematic to determine the number of revolutions per minute;
  • Phillips screwdriver. It is needed so that it is possible to unscrew the screw (T);
  • Compressor with a special gun connected to them. A purge device will help get rid of excess litter and dirt, as the carburetor must always be clean.

Many Husqvarna chainsaws use special cross-section adjusting bolts. Look in advance which are installed with you and purchase the appropriate kit. This will help to avoid many difficulties at the initial stage.

Husqvarna Chainsaw Carb Adjustment

Like all other saws, husqvarna has the same carb adjustment algorithm. Therefore, the instruction will be relevant for other tools and models of chainsaws such as Husqvarna 142, 236.

Before starting work, make sure the air filter is clean and that all other components are working properly. The fuel supply to the float chamber should work without interruptions, and the ignition system is configured correctly and has a fresh candle.

  • Set the carburetor to factory settings. Do this with the engine stopped.
  • Now you can start the engine and be sure to warm it up for several minutes. Adjustment of the XX carburetor Husqvarna 137 is carried out only on a warm engine.
  • Turning the screw L clockwise, you need to set the highest revolutions of the crankshaft, then turn back a quarter of a turn. Use screw T to adjust the crankshaft speed so that the chain does not rotate. It should not be set in motion without pressing the accelerator.
  • Now you need to set the maximum speed and their power. It is enough to connect the tachometer to the ignition system and set the maximum possible speed using the accelerator. Compare them with the passport data. If they differ, then unscrew or tighten the screw H. By changing the range, you can create restrictions in order to make the saw work efficiently and save the motor resource.

What you should pay attention to?

As soon as the adjustment of the Husqvarna carburetor is completed, you need to make sure that the engine is stable and that the saw easily picks up and slows down. The rotation of the circuit at idle speed is considered an abnormal phenomenon, therefore, it is necessary to adjust its connection with the clutch again using screw H.

Do not forget that the unit is not configured immediately: you need to wait a while, since the Husqvarna chainsaw does not immediately respond to the change in the position of the screws. This time can vary from 5 to 15 seconds. The table does not prescribe this time, so you can only find out experimentally.

If after adjustment a huge amount of smoke appears during operation, then the flow of the fuel and oil mixture must be adjusted. For these purposes, rotate screw L.

What is the factory setting for the Husqvarna chainsaw carburetor?

In order for the chainsaw to start anyway even with the wrong setting, the factory settings of the H and L screws are applied. Most Husqvarna chainsaws can be started by unscrewing both screws exactly one and a half turns. Only then can the position of the screws be changed in order to achieve the required fuel consumption and maximum work efficiency. XX is also regulated after these manipulations.

If you still have questions about adjusting the carburetor on the Husqvarna 137 chainsaw and other models in this line. I recommend watching this video:

How to repair a Husqvarna carburetor with your own hands?

During operation and diagnosis, defects in the carburetor can be detected. Most of them can be eliminated on their own with a minimum of knowledge and without contacting a specialized repair center.

Among the methods of elimination can be identified:

  • Replacement of various gaskets at the joints of tight parts;
  • Cleaning or replacing carburetor filter elements;
  • Replacement of pump elements or valves;

Almost all of the above details can be positioned as a repair kit, which is used for short-term repair of carburetors. After installing them, the carburetor of the Husqvarna 137 chainsaw can forget about the malfunctions for a long time, and regulation will become easier.

How to install a repair kit?

If the problem touched the carburetor nozzle, you can try to fix a serious malfunction with your own hands. However, the manufacturer recommends to deal with this nuisance only by replacing the node.

To remove the carburetor, you need to completely clean the saw from sawdust and shavings. To do this, use a compressor and a gun with compressed air. Next, the filter cover is unscrewed and the filter element is removed. After that, all throttle actuators and thrusts are disconnected from the husqvarna carburetor. Now you can remove the carburetor from the saw.

Next, you need to completely disassemble the carburetor and replace all the elements that the repair kit offers. Namely, spare parts and gaskets. This will save future damage.

Now you know how to adjust the carburetor of the famous Husqvarna 137 chainsaw.