How To Adjust The Carburetor On A Husqvarna 236 Chainsaw
DIY chainsaw carburetor repair instructions
DIY chainsaw carburetor repair instructions A chainsaw is needed in construction, gardening, and landscaping. Its presence greatly simplifies the implementation
DIY chainsaw carburetor repair instructions
A chainsaw is needed in construction, in gardening, and in landscaping. Its presence greatly simplifies the implementation of a number of tasks for wood processing. The main unit of this tool is the engine, the operation of which largely depends on the state and settings of the carburetor. This is where the fuel mixture is prepared. This means that if the saw does not start, stalls or does not provide the required power, it is likely that the reason for this is improper operation of the carburetor. Fortunately, you can handle this yourself in many cases. Only for this you need to know and understand the device and principle of operation of this unit and, of course, the chainsaw itself.
How to recognize a carburetor malfunction?
Chainsaw carburetor operation diagram
Carburetor settings can be affected by:
- Lack of fixing the adjusting screws;
Chainsaw adjusting screws
New CPG chainsaw Husqvarna 365
Chainsaw air filter with nylon insert
If any problems are found, you should immediately fix them. But how do you know if it’s a carburetor? To do this, watch how your tool works.
A list of typical signs that carburetor settings are out of tune include:
- Unstable motor operation
As a rule, the reason for this is the use of an incorrect (lean) fuel mixture.
- Excessive consumption of fuel
It is expressed in an increased emission of exhaust emissions, which become black. This means that the fuel is not completely consumed, i.E. Oversaturated mixture.
Carburetor set correctly. Saw starts the first time
- Arbitrary changes in engine power
May be associated with damage to the fastening of the adjusting screws or the protective cap.
- Increased fuel consumption accompanied by vibrations and pops
It speaks of critical wear of the piston group, therefore, adjusting the carburetor will postpone the overhaul only for a while.
- Sneezing and jerking of the engine
This picture is observed when the carburetor channels are clogged or its filters are malfunctioning. In this case, the adjustment should be carried out only after thorough flushing of the assembly.
Chainsaw fuel filter
Despite the fact that the carburetor is the most difficult part of the engine, you should not be upset if it detects malfunctions in its operation. Instead, you need to arm yourself with some tool, a knot design, and healthy logic.
Chainsaw carburetor being repaired
What is the primary adjustment for?
Chainsaw initial break-in: working with thin material
Most modern chainsaws are sold adjusted. Nevertheless, the quality of the factory settings does not interfere with checking. In the end, you will have to work with the instrument.
When starting the saw for the first time, it should work in a gentle mode. Therefore, for several hours after the start, it is recommended not to overload the engine and only cut small branches and trunks up to 10 cm thick.
Simple rules will help to insure against malfunctions in the carburetor of the chainsaw:
- Always mix gasoline and oil according to the manufacturer’s numbers.
The proportions of the fuel mixture for the chainsaw engine
The chainsaw must start correctly, ensure a stable sprocket speed and smooth power increase / decrease. When the engine is running, there should be no extraneous knocks, pops and noises.
Professional hand-held chainsaw at work
The main thing during the initial running-in of the tool is to ensure that the fuel consumption corresponds to the power used, i.E. In practice, the saw should not go out, “sneeze”, smoke and work in jerks.
How does a chainsaw carburetor work?
Stihl MS 181 C BE chainsaw carburetor
Chainsaw carburetors may vary in design. However, their basic elements and the principle of operation remain approximately the same.
- The basis
This is a wind tunnel, across which the air damper is located. With its help the intensity of the air supply is regulated.
This part is located where the base tube is narrowed. Here the air flow rate increases, i.E. Air is always supplied to the carburetor under some pressure.
In this area, the fuel comes into contact with the air flow. Fuel enters the atomizer from the float chamber through the nozzle (metering device).
- Float chamber
This is a container that allows you to keep the fuel mixture in a stable state.
Structural diagram of a chainsaw carburetor
The chainsaw carburetor works according to the following principle:
- When the engine is started, the main flap opens and a stream of air is supplied into the air channel at a certain speed;
- The air flow rate, as well as the level of the float in the chamber, are regulated by the position of the damper, namely, due to the difference in pressure in the float chamber and the air channel;
- The fuel from the float chamber is sucked into the nozzle, and from there into the diffuser;
- Passing through the diffuser, the air captures the fuel entering there;
- The resulting mixture is fed into the cylinder cavities through the inlet channels.
The principle of operation of the chainsaw carburetor
The pressure in the float chamber is approximately equal to atmospheric, but in the air channels of the carburetor, when the engine of the chainsaw is started, a vacuum occurs. Opening the damper increases the air flow rate. As a result, more fuel flows into the carburetor and the engine speed increases.
DIY disassembly: nothing complicated
Chainsaw carburetor repair tool
First, you will have to dismantle the chainsaw carburetor. This is done in this order:
- To get to the carburetor, you need to remove the top cover of the chainsaw, which is fixed with three bolts.
Removing the carburetor cover
Removing the fuel hose and drive rod
Removing the throttle cable
After removing the gasoline hose, the carburetor is ready for disassembly
Disassembly of the carburetor must be carried out in the manner prescribed by the design and functional solutions of its elements. Chainsaw carburetor parts do not differ in size, so they need to be folded carefully and in order, trying not to lose anything.
Dismantling the chainsaw carburetor for
After disassembly, it is necessary to carry out a defect finding and replace damaged or worn parts. Next, the entire set should be rinsed with a special product, dried and wiped with a dry, lint-free cloth. The jets and tubes of the assembly must be blown out with compressed air, or, in order to more thoroughly remove formations on their inner surfaces, they must be treated with ultrasound before that.
What is responsible for the air supply
Two dampers are responsible for the air supply, installed on the diffuser chamber. The first one can regulate the amount of air at the moment the accelerator is pressed and is called the throttle, and the second ensures the limitation of the air supply at the moment when the chainsaw is cold started. To facilitate starting, the damper 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 is worn out.
A check valve injector is used to spray fuel into the cylinders.
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, manifest themselves when this mechanism does not work properly.
- The most common mistake is storing the instrument 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.
- The second problem is an increase in the amount of air in the mixture, caused by its suction from the outside when the valve does not work properly. It is no longer possible to regulate here, since in this case only valve repair or its replacement helps, since the saw will not react to the adjusting screws.
Unlike the car, the carburetor setting of the chainsaw provides for three adjusting screws that are responsible for the quality of the mixture, the amount and nominal speed of the crankshaft of the Husqvarna engine:
- Screw L. Designed to adjust the number of revolutions when working in medium modes and regulates low revolutions;
- Screw H. Adjusts the number of high revolutions and thrust of the installation;
- T. Designed to adjust the total amount of fuel and adjust 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, then 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 early wear and failure. This principle is embedded in many devices.
No table lists the settings parameters. Therefore, you should not look for these data in special literature, but only strictly follow the instructions. The table in the passport has only informational value regarding the characteristics of the engine.
Adjusting the carburetor of your Husqvarna chainsaw
Like all other saws, the husqvarna has the same carburetor 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 that 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 spark plug.
- Set the carburetor to factory settings. This must be done with the engine stopped.
- Now you can start the engine and be sure to warm it up for a few minutes. The Husqvarna 137 carburetor XX can be adjusted only when the engine is warm.
- Turning screw L clockwise, you need to set the highest speed of the crankshaft, then turn back a quarter of a turn. Adjust the speed of the crankshaft with screw T so that the chain does not rotate. It must 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 your passport data. If they differ, then unscrew or tighten screw H. By changing the range, you can create restrictions to make the saw work efficiently and save the motor resource.
What you should pay attention to?
Once the Husqvarna carburetor adjustment is complete, you need to ensure that the engine is running smoothly and that the saw can easily rev up and down. It is considered abnormal to rotate the chain when idling, so it is necessary to re-adjust its connection to the clutch with screw H.
Do not forget that the assembly is not immediately set up: you need to wait a while, as the Husqvarna chainsaw does not immediately respond to changes in the position of the screws. This time can range from 5 to 15 seconds. This time does not prescribe the table, so you can only find out experimentally.
If, after adjustment, a huge amount of smoke appears during operation, then the supply of the fuel and oil mixture must be adjusted. For these purposes, rotate the screw L.
How does the carburetor work on a Husqvarna 137 chainsaw?
On chainsaws of these models, the Walbro carburetor is most often installed from the factory. Before adjusting the Walbro carburetor on a Husqvarna chainsaw, you need to have a minimum understanding of its structure and know how it works.
When is carburetor adjustment necessary?
The reasons why it will be necessary to adjust this unit can be listed for a very long time.
Among the main faults are the following:
- Increase in idle speed;
- The appearance of a large amount of smoke during operation;
- Deterioration of starting properties;
- Insufficient tool power while cutting.
This is not a complete list of all known faults. Sometimes a procedure such as adjusting the carburetor on a Husqvarna chainsaw may need to be done after a major overhaul of the power plant or after maintenance.
The developers of the Husqvarna 137 write in the passport that the carburetor adjustment must be carried out before and after running in the tool.
What is responsible for supplying a mixture of fuel and oil
For accurate delivery of fuel with oil, the operation of the fuel pump is used, which is mechanically driven 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 correct operation of the metering chambers and the pump is organized, which improves the operation of the chainsaw.
The factory default setting for the Husqvarna carburetor is the position of the screws (H) and (L), in which a working chain saw is guaranteed to start. For Husqvarna tools, this is one and a half turns from fully tightened screws (H) and (L). In the process of adjustment, you must first set the screws to the standard position, then start the chainsaw and make precise adjustments to the power, the number of maximum revolutions and idle speed.
Nuances of adjustment
After adjusting, the chainsaw should easily pick up and drop speed, work stably at low and high speeds. If the saw chain rotates at idle after adjusting the carburetor control screws, this is a sign that the adjustment has been made incorrectly and the position of the screw (T) must be corrected.
Also, when adjusting the Husqvarna carburetor, it is worth considering the response time of the chainsaw to the rotation of the screws. The settings do not change immediately, but within five or ten seconds.
One of the indicators of an incorrect adjustment is a strong smoke during the operation of the saw, which indicates a large amount of fuel entering the combustion chamber. If this situation occurs, the position of the screw (L) must be corrected.
DIY carburetor repair
If in the course of carrying out a complete diagnosis of the Husqvarna chainsaw, carburetor defects were found, then some of them can be repaired without contacting a Husqvarna AB service center. For example, you can independently:
- Change the gaskets under the covers of the main chamber and the fuel pump;
- Clean or replace the mesh filter;
- Replace the diaphragm or needle valve of the main chamber;
- Troubleshoot the fuel pump diaphragm.
Gaskets, diaphragms and a rocker needle valve can be found in the repair kit that is available for each Husqvarna chainsaw carburetor model.
Also, if you have some experience, you can try to restore a faulty injector valve, but you cannot guarantee a positive result when trying to restore an injector, if it is faulty, manufacturers recommend changing the carburetor completely.
The first thing to do before removing the carburetor from Husqvarna is to clean the saw with a compressor, since dirt can interfere with a quality repair. Next, you need to open the top cover of the chainsaw, remove the air filter, disconnect the rods from the control levers of the air and throttle valves. Then unscrew the screws securing the carburetor.
It is quite easy to disassemble the carburetor body for repair. The main chamber cover is held in place by four screws that can be removed with a regular screw, the fuel pump cover is secured with one wide screw.
Below is a look at which it will become clear exactly how you can repair the carburetor without contacting a Husqvarna service center.
Adjusting the carburetor of your Husqvarna chainsaw
Modern chainsaws have a complex system and consist of several main units that periodically require maintenance and adjustment. In this article, we’ll talk about how to adjust the carburetor on your Husqvarna chainsaw.
Husqvarna carburetor adjustment algorithm and description
The Husqvarna carburetor adjusts in the same way as the carburetor settings on other brands of chainsaws.
The order of work is as follows:
- The cut-off saw is set to the factory settings for the Husqvarna carburetor.
- The engine starts and the saw warms up for a few minutes.
- By turning the screw (L) clockwise, the position is found at which the engine develops maximum speed, after which the screw must be turned back 1⁄4. If at the same time the chain of the chainsaw rotates, then it is necessary to reduce the idle speed by adjusting the position of the screw (T).
- The next stage is adjusting the power of Husqvarna at maximum speed and adjusting their number. To do this, the tachometer is connected to a running chainsaw, the throttle stick is squeezed out to full, after which the tachometer readings are checked. If the value of the maximum revolutions differs from the maximum number recommended by the manufacturer, then by changing the position of the screw (H), the tachometer readings are returned to normal.
When does the carburetor of a Husqvarna chainsaw need adjustment?
There are a lot of problems that can be solved by adjusting the carburetor. Adjusting the carburetor of a Husqvarna chainsaw is necessary when such malfunctions appear:
- Increased idle speed;
- Strong smoke when operating the tool;
- Difficulty starting a cold or hot engine;
- Lack of traction and reduced maximum speed.
This is by no means a complete list of problems that can be solved by tuning the Husqvarna carburetor. In some cases, the quality and quantity of the fuel mixture is adjusted after an overhaul of the engine or in the process of scheduled maintenance of the chainsaw.