How to adjust the carburetor of a Chinese chainsaw
Methods of work
Adjustment of the Husqvarna carburetor is made with screws L and H, if gasoline is used in the work, which differs from that recommended by the supplier. If the octane number is low, turn the screw by unscrewing it to increase it. This will increase the revs and power. But with an increased octane number, to lower it, turn the screw in the opposite direction by tightening it. This will help reduce engine speed.
When adjusting the Husqvarna carburetor, use the screws in the following order: L. H. T. Observing the exact angles of rotation, you will follow the requirements that will allow you to maintain the best operating parameters of the engine. There is no universal adjustment method. The procedures may differ from one another. But the process is usually divided into two stages. The first is basic, the second is final. The basic one is performed with the engine off, while the final stage provides for warming up the engine for 10 minutes.
Signs and Causes of Poor Volatile Performance
Signs of malfunctioning of the chainsaw carburetor:
- The engine starts badly and stalls quickly. Possible Cause: Lean Mix.
- Excessive (more than normal) fuel consumption. In addition, heavy (more than usual) exhaust emissions. Possible Cause: Supersaturated Mix.
- The engine doesn’t want to run at all. There are two reasons: there is no gasoline (the fuel jet is clogged) or there is no spark (the spark plug is faulty, the high-voltage wire is broken or the electronic unit is out of order).
Failure of settings by itself is rare and the reasons, as a rule, are as follows:
- Violation of the fastening of the adjusting screws from a faulty (damaged) cover of the protective casing. Possible Cause: Rough touch, attempted rough adjustment, or strong external vibrations.
- Wear of the piston group. Here, of course, adjusting the carburetor won’t help much. Consider repairing your ICE or replacing your saw.
- Dirty carburetor. Probable reason: breakdown or unsatisfactory condition of the air filter, the use of low-quality fuel, the ingress of scale, the smallest sawdust into the fuel channels, etc. In such cases, the entire fuel system is flushed first, and only then. the adjustment.
Setting up a Chinese chainsaw
The procedure can be challenging. Some models are modeled after the expensive and high quality models that famous brands produce. For this reason, on some Chinese counterparts you can see.
- Idle speed screw. This adjusts the engine speed at idle speed. If it is set too low, the saw will not work. If you set it high, you might run into chain problems. this is dangerous!
- The low speed adjusting screw is a low speed setting. This is an adjustment that controls the idle air / fuel mixture. In the first case of incorrect adjustment, the saw will not start at idle speed. In the second case, an engine breakdown will occur.
- High speed adjusting screw. This is an adjustment that controls the air / fuel mixture at high revs. Incorrect setting leads to high revs of the chainsaw.
Chainsaw carburetor device
To understand how to properly set up a chainsaw, you need to know the nuances of the device of its main components, in particular the carburetor.
It works on the same principle as internal combustion engines. a mixture is burned in the cylinder, provoking a small explosion. The pressure from the explosion pushes the piston, which in turn rotates the crankshaft. Movement changes into a moment of rotation, he moves the chain through the sprocket. The engine, at optimal operation, consumes up to 10 mg of fuel in each cycle. The mixture for the engine is prepared in the carburetor.
The purpose of the carburetor is to prepare a mixture of fuel and air in the desired ratio. If the device prepares it with irregular proportions, then the functioning of the engine itself is also disrupted. The wrong mixture is called lean or oversaturated. In a lean mixture, the amount of oxygen is increased in relation to the fuel, in a supersaturated mixture, on the contrary. In both cases, malfunctions of the mechanism begin, which require elimination.
The basic design and principle of operation of the carburetor have a common base, but differ depending on the model of the chainsaw. For example, if you need to set up a Chinese chainsaw, then you should familiarize yourself with its service book and the structure of the device. In general, the work of the carburetor and its main elements are as follows:
- the base is a tube, in terms of its functional properties it is similar to the aerodynamic one. An air stream enters through this element. It is crossed by an air damper, which blocks the cavity or opens, this increases the amount of incoming air or decreases;
- diffuser in the base. increases the speed of air passage in the hole provided for the fuel flow;
- atomizer. through it, the fuel enters the air stream. The fuel flows into the atomizer through the jet from the float chamber;
- float chamber. container for keeping the mixture at a stable level.
yandex_partner_id = 53889;
yandex_site_bg_color = ‘ffffff’;
yandex_ad_format = ‘direct’; yandex_font_size = 1.0;
yandex_direct_type = ‘vertical’;
yandex_direct_border_type = ‘ad’;
yandex_direct_limit = 1;
yandex_direct_title_font_size = 2;
yandex_direct_links_underline = true;
yandex_direct_bg_color = ‘ffffff’;
yandex_direct_border_color = ‘ffffff’;
yandex_direct_title_color = ‘0C77EC’;
yandex_direct_url_color = ‘000000’;
yandex_direct_text_color = ‘000000’;
yandex_direct_hover_color = ‘CC0000’;
yandex_direct_favicon = true;
yandex_no_sitelinks = true;
The general principle of functioning of the carburetor:
- A fast air flow goes through the channel, the damper regulates the speed of this flow.
- Opening the channel adjusts the position of the float.
- Air flows through the diffuser, mixing with the incoming fuel and spraying it.
- The resulting mixture enters the cylinder through the intake manifold.
The pressure indicator in the float chamber is close to atmospheric, in the air channel this indicator is rarefied. The difference in performance ensures the suction of fuel through the jet into the air channel. A larger opening of the air damper results in a larger volume of air entering, which means more fuel. An increase in the incoming fuel leads to an increase in engine speed. The principle of operation of the simplest carburetor is described. Having mastered the basics of its device, it is easier to understand and determine the purpose of the remaining elements.
How to properly adjust the carburetor with your own hands?
After rinsing and completely cleaning the carburetor, assemble it and proceed with the adjustment. First of all, you should understand the purpose of the adjusting screws. The instruction will help with this, but some general points should be taken into account immediately. The most common designations for screws:
- H. Regulates the state of the main jet, that is, it regulates the maximum rotation speed of the engine shaft;
- L. Adjusts the no-load currents (responsible for the minimum shaft rotation speed)
- T. Adjusts the idle idle engine. It can also be designated LA or S, but this is not the case on some carburetor models.
Turning screws H and L clockwise depletes the air-fuel mixture, and counterclockwise enriches it (the amount of gasoline increases). When the screw T rotates, the idle speed of the shaft changes. It increases clockwise and decreases in the opposite direction.
Figure 2. Carburetor adjustment mechanisms
Before proceeding with direct actions, you should find and carefully study the information on the position of the adjusting screws (the magnitude of the angles of rotation when adjusting). This information is available in the instructions for your chainsaw. Then you need to prepare the workplace. Lay out the pollen on a flat horizontal surface, directing the chain backward away from you. Remove all covers, foam rubber and air filter. In this case, the preparatory operations are considered completed, you can proceed to the main part of the work.
Carburetor Adjustment Procedure:
- Gently tighten screws H and L clockwise until they stop. Be careful not to break the screws. This will lead to a complete loss of the carburetor.
- Unscrew both screws one and a half turns.
- Start the engine for 10 minutes and warm it up. This is a necessary moment, since it is impossible to correctly adjust the carburetor on a cold engine.
- Turning screws H and L, alternately adjust the shaft rotation at maximum and minimum speed.
- By adjusting the position of the screw T (or it may have another designation), the idle speed of the chainsaw is adjusted. It is necessary to achieve smooth and stable engine operation. It is important to monitor whether the chain is idle or not. If it moves, turn the screw a little more counterclockwise.
You can check engine performance visually and audibly. Too rich mixture will cause thick smoke from the exhaust. When a lean mixture is fed, a whistling sound is heard while the saw is running. Excessive economy is harmful. If the L screw is set to “reset” the fuel, there will be problems with starting the engine. If screw H is tilted, the saw will noticeably lose strength. The correct setting can be determined by the following criteria:
- At idle speed, the engine is not delayed, and the chain is stationary;
- When the engine is running, there is no excessive smoke from the exhaust pipe;
- Engine demonstrates good throttle response (picks up speed quickly when accelerator is pressed).
A detailed description of the setting is available in the instructions supplied with the instrument in the shipping kit. This should be carefully considered as there may be some peculiarities or specific requirements set by the manufacturer and related only to this saw model. If all requirements are met exactly, the performance of the chainsaw will be restored to its original state.
Husqvarna 137 Mix setting
Rapid adjustment of the air-fuel consistency to restore the start of benzapila.
An ordinary slotted screwdriver will not work for adjustment, since the adjusting screws on Husqvarna chainsaws can have different sections. We’ll have to purchase a special, this is a feature of the repair of Husqvarna chainsaws, they created everything so that the saw could be repaired exclusively in the Husqvarna special service.
Setting Fuel Mixture to Factory Settings, Chainsaw
Advantages and disadvantages of the cutting device
Chainsaws have been in demand since the industry began producing economical, low-cost devices designed for a wide consumer range. They became affordable and almost completely replaced hand saws. Chainsaw advantages:
- The speed of wood processing is 5-10 times faster than a conventional hand saw.
- Ease of use laterally.
- Low operational safety. The greatest risk of injury is when the chain catches on something solid and the engine continues to run, the chain will open and result in fatal injury. It is recommended to wear special protective helmets and goggles when working with such a tool.
- The need for service. In a chain saw, fine dust enters the mechanism, mixes with the chain lubricating oil and creates dense dirt, so it needs to be cleaned regularly.
But I want to warn you, be careful when adjusting the carburetor. Therefore, like depletion and enrichment of the fuel consistency, also playing with the speed of revolutions, has very severe consequences.
How to find a malfunctioning carburetor
However, the adjustment may be preceded by the repair of the carburetor itself, when it cannot fulfill its function as a fuel mixer.
If fuel for some reason does not enter the engine, you need to check the condition of the fuel supply unit. Often the reason is the supply of low-quality gasoline, as a result, the fuel passages are clogged.
If the fuel mixture has stood for a long time, the additives have collapsed, the mixture can clog the passages and grate with sediment. In this case, a lengthy flushing is required, which is done with solvents in a service workshop.
When carburetor adjustment is required
The new chainsaw is adjusted to the recommended mix. All you need to do is fine-tuning with three screws; you don’t need to disassemble the carburetor. The purpose of the adjusting screws:
- “L” regulates the fuel supply at low rpm;
- “H” is needed to regulate the maximum fuel supply;
- “T” idle speed control.
Since the saw carburetor is adjusted by ear with the engine running, safety precautions must be observed. The saw should be positioned securely with the cutters pointed in a safe direction for those present.
Carb Adjustment on The Chinese Chainsaw
Before starting the manipulation, it is necessary to mark the initial position of the screws with paint or felt-tip pen. The exact values for setting the carburetor of the chainsaw for each model are in the instruction manual.
However, more often, a carburetor tincture is required after eliminating a tool malfunction. The reasons may be:
- violation of the protective cap and imbalance of the screws;
- engine piston wear, requiring a different mixture to work;
- unsatisfactory operation of the carburetor itself.
How to adjust the carburetor on a particular model chainsaw? Perform operations sequentially, guided by the instructions. Here is the algorithm, the general sequence of actions.
There are two stages of adjustment:
- basic, with the engine off;
- thin. on a warm engine, idling.
The basic setting is only for the low and high speed fuel screws. Smoothly, without haste, you should completely close the flaps to the stop. Also slowly open both screws counterclockwise by 1.5 turns. Then start the engine and warm it up for 10 minutes.
How to adjust the carburetor on a chainsaw with the engine running:
- adjust the idle speed with the screw “T”, turning counterclockwise until the engine runs at idle speed;
- check the speed of the set of revolutions, with slow unwinding, turn the screw L an additional 1/8 turn;
- set the highest rotation speed on the tachometer with screw H;
- check the operation of the carburetor at idle speed finally.
Why and how the chainsaw carburetor is adjusted
How the carburetor works
- a constricted air tube;
- fuel supply system;
- regulating air damper.
Air at atmospheric pressure, passing through the air cleaner, is supplied to the narrowing zone, where its flow rate is regulated by a flat damper overlapping the section. After constriction, a vacuum occurs in the pipe. As a result, the vacuum sucks in fuel from the fuel supply tube, the exit from which is regulated by a fuel needle connected to the float chamber by a jet. The device of the carburetor of a chainsaw, in principle, does not differ from other fuel mixers of internal combustion engines.
The principle of mixing is to regulate the air damper, float level, depending on the degree of vacuum. We open the air. more fuel comes in, the engine rises. The correct ratio of the fuel mixture depends on the precise adjustment of the chainsaw carburetor. If there is a lot of air in the fuel, the power drops, the mixture is called lean. With a lack of air, there is a large fuel consumption, incomplete combustion, carbon deposits on the cylinder and exhaust of unburned fuel. This says the mixture is oversaturated.
Chainsaw Ural, according to the instructions, requires running-in with the use of an enriched fuel mixture. Therefore, the carburetor comes from the factory with the setting for the run-in period. When switching to operating mode, the node is reconfigured.
Signs of good chainsaw carburetor performance:
- the engine runs smoothly, sounding like a four-stroke;
- fast set of revolutions;
- the chain does not spin when idling.
If the troubleshooting is carried out by hand, it is necessary to free up space and expand the small parts. You will need a tool:
- screwdriver for cross-thread heads;
- socket wrench or head M6;
- pure gasoline.
The main thing is to properly release the unit from the installation site, cleaning it from the outside from dirt. The air intake is removed, opening access to the carburetor and the suction draft. Remove the throttle lever by lowering the carburetor choke. Release the part by removing the choke lever, lifting the wire along with the lever towards you, picking it up on the left.
Rinse the freed carburetor in gasoline, blow out with air, clean the grate by injecting with a thin needle.
When reassembling the assembly, make sure that the spring under the needle arm is in place. If you forget it, the fuel is not cut off, the candle is damp and does not give a spark.
It happens that the gas key on the Stihl saw slightly wedges. In this case, the throttle must be cleaned of plaque. It is necessary to protect the damper with tinning after cleaning.
After assembling the carburetor, setting it in place, adjust as described above.
How the carburetor on a chainsaw is adjusted. instructions
A chainsaw is a complex unit, the operation of which is based on a two-stroke type internal combustion engine. The internal combustion engine requires the use of a carburetor. In this mechanism, fuel is mixed with air, and this mixture is fed into the engine cylinder for combustion. The operation of the internal combustion engine largely depends on the carburetor, which needs periodic adjustment. Chainsaw carburetor adjustment can be done by hand, but for this you need to know the instructions, which are described below.
Chainsaw carburetor design
A carburetor is a device in which fuel is mixed with air, and this mixture is supplied to a cylinder for combustion. During combustion, the crankshaft is driven, to which the drive sprocket is connected to drive the saw attachment. the chain. The absence or malfunction of the mechanism in question will lead to the inoperability of the tool, therefore it is important that the device is in good working order and adjusted.
The design of the chainsaw carburetor consists of the following components:
- Solid aluminum alloy body. The use of aluminum for the manufacture of this mechanism helps to lighten the weight of the tool
- Diffuser for air supply, located on the side of the entrance to the mechanism
- Nozzles. valves that serve to regulate the flow of the mixture
- Sprayer. a device from which the fuel mixture enters the combustion chamber of the cylinder
- Float chamber. a device for creating and maintaining a certain level of fuel
A detailed design diagram of the device in question is shown in the photo below.
Chainsaw carburetor tuning is an important step every sawyer has to deal with. The chainsaw needs adjustment not only after purchase, but also in the following cases:
- Before running in the tool. How to set up the mechanism for the correct running-in of the chainsaw is described in detail here
- After the end of the running-in process
- After overhaul of the internal combustion engine
- During the operation of the tool, when malfunctions occur during operation and starting the motor
There are 3 adjustment screws at the base of the mechanism (2 screws on some Chinese models), which are the control panel for the user. It is with the help of these screws that the carburetor of the chainsaw is adjusted independently and quickly. It is possible to adjust an important unit of the tool even in the field without resorting to the help of specialists.
Chainsaw carburetor adjustment instructions
Setting up a chainsaw carburetor begins with a preparation procedure. The preparation is based on the following actions:
- Check the air and fuel filter for contamination, and if any, these elements need to be cleaned
- Check the diaphragm for damage
- Serviceability of the needle valve
- No air leaks, which can occur due to leaky oil seals, gaskets and seals
After making sure that the carburetor is in good working order, you can adjust it yourself. It is possible to restore the mechanism to its factory settings, but it is not always necessary to do this. Instructions on how to adjust the carburetor on Shtil, Husqvarna, Makita, Dolmar, Champion, Sadko and others chainsaws are described below. Initially, we find out what each screw in the mechanism is intended for:
- Screw H. main jet, which is responsible for setting the maximum number of revolutions of the tool
- Screw L. XX jet, which is needed to set low idle speed
- Screw LA or S or T. increasing and decreasing the amount of mixture supplied to the cylinder
Chainsaw Carburetor | How to Tune & Adjust ‘Correctly’
Each type of tool of the brands Stihl, Husqvarna, Makita, Dolmar, Partner is accompanied by an instruction, which contains a section that describes this process in detail. It will not hurt if you find the instructions before setting up, and read it before turning the screws.
Preparing for setting up the chainsaw carburetor includes performing the following manipulations:
- Installing a chainsaw with your own hands on a flat surface. It is also recommended to secure the tool so that it does not move when you push the screws with a screwdriver.
- Steer the tire away from you
- Provide a safe distance for others, since the carburetor of the chainsaw is adjusted with the engine running
- It is not necessary to remove the carburetor from the unit to adjust it
This is not the end of the regulation process, but the tool can already be tested in action. For beginners and inexperienced sawers, it is recommended to complete the setup process at this point. For a more accurate adjustment of the carburetor of the chainsaw, you need to set the maximum speed. Let’s start setting up the H screw for experienced sawers:
- Determine the enrichment of the mixture by the exhaust. To do this, we develop the revs to the maximum, and look at the nature of the exhaust. The presence of gray smoke and strong vibration of the instrument indicate excessive enrichment of the mixture.
- The tachometer (if connected) will show a large number of revolutions. more than stated in the characteristics
- To reduce the maximum speed, you need to move the screw H a few turns counterclockwise
- The maximum speed is checked again, and the process is repeated if necessary.
You can make sure that the instrument is configured correctly by the following signs:
- The chain does not move when idling
- The engine works like a four-stroke engine
- When you press the throttle stick, the engine responds quickly and revs up
To make the most accurate tuning, you will need to use a wired or wireless tachometer.
On the Stihl 170 and 180 chainsaw, the process of adjusting the chainsaw carburetor looks a little easier, since there is only one screw. A detailed description of the process of regulating the carburetor on the Stihl MS180 chainsaw is presented in the video.
How does a chainsaw carburetor work. the principle of operation
The operation of the unit in question, despite its complex design, is simple and understandable even for beginners. The principle of operation is based on the following actions:
- As soon as the engine of the internal combustion engine starts, the air damper opens.
- In the area of narrowing of the diffuser 16, the flow of incoming air is accelerated, which is mixed with the gasoline-oil mixture
- The gasoline-oil mixture is supplied through the nozzles numbered 15 and 12, and the air, before passing through the damper 7, passes through a filter located in front of the inlet
- The damper 8 is located behind the diffuser, and serves to regulate the supply of the amount of the mixture to the combustion chamber
- Screws 17 and 10 adjust the volume of gasoline that passes through the jets. On the carburetor control panel, these screws are labeled L and H
- The needle valve 11 regulates the volume of the fuel mixture in the float chamber 14. To adjust the position of the needle valve, a diaphragm 13 is installed in the mechanism
- Another membrane 4 is responsible for supplying fuel to the combustion chamber of the cylinder. The position of this membrane depends on the number of revolutions of the internal combustion engine
- A fine filter is used to clean the gasoline-oil mixture
The simple principle of operation of the carburetor ensures the smooth operation of the internal combustion engine. The quality of the setting determines how the tool will behave at idle and during operation. The mechanism under consideration has a direct impact on the performance of the entire tool. The service life of the tool depends on the quality of the adjustment.
Carburetor Air / Fuel Adjustment. When Needed
The first adjustment of the chainsaw carburetor is done immediately after purchasing a new tool. This is done in order to run the tool motor. To run the internal combustion engine of a chainsaw, you need to limit the maximum speed, which is done with the help of adjusting screws. As soon as the run-in is completed, which lasts 2-3 tanks of burned fuel, it is required to re-adjust, but only now in order to establish the maximum speed.
In addition to running-in, chainsaw carburetors are adjusted when:
- Knocking down the settings set after running
- If the internal combustion engine does not start well
- If the engine does not develop speed or when you press the gas, the chainsaw stalls
- Wear of the piston group, but only in this case, adjusting the carburetor of the chainsaw is a temporary measure, since the internal combustion engine needs a major overhaul
- If the engine does not idle
- Unit vibrations
- Carbon deposits on the spark plug
- Increased fuel consumption. This phenomenon can be detected by the excess amount of smoke. If you unscrew the candle, then it will have a black color with carbon deposits.
Many malfunctions during the operation of the gasoline unit arise precisely because of the incorrect setting of the chainsaw carburetor or when they are knocked down. To restore the tool to its previous performance, it will be necessary to adjust the mechanism. Many beginners trust this process to specialists, for which the masters take a lot of money. It’s time to deal with the adjustment, and carry it out on your own, since this process does not require disassembling the mechanism.
How to adjust the carburetor on a Chinese instrument
Let’s figure out how to properly adjust the carburetor on a Chinese chainsaw of different brands. The setup principle is similar to that described in the material above. First you need to inspect the tool, and identify the presence of adjusting screws. Usually the T screw is on the top and the L and H screws are below. Access to these screws does not always require you to remove the protective cover or shroud.
If the Chinese chainsaw has a different number of screws, then based on their number, you need to make the appropriate adjustment. The device and principle of operation of all chainsaws of different brands and manufacturers is approximately the same, therefore, there will be no problems with adjustment.
It is always easy to do any new job, if there are instructions, so do not be afraid to tackle the setup. Even if you do something wrong, then by contacting a specialist, he will definitely point out your mistakes. If you have any difficulties with adjusting the chainsaw carburetor, then describe them in the comments. Experts, masters and just amateurs, together with the founder of the portal, will help you understand this issue.
The design and principle of operation of the chainsaw carburetor
The chainsaw carburetor also consists of the following main components:
- one-piece body made of light aluminum alloy;
- a diffuser located at the entrance to the carburetor;
- nozzles, special valves designed to regulate the supply of a combustible mixture;
- float chamber.
Below is a diagram of a Walbro carburetor, which chainsaws are very often equipped with. Using this scheme, you can study in more detail the internal structure of the chainsaw carburetor.
The carburetor can have 2 or 3 adjusting screws with springs. The adjusting screws are designed so that there are needles (cones) at their ends. The screws have a right-hand thread, that is, they are twisted in a clockwise direction.
The work of the chainsaw carburetor is as follows.
- After starting the internal combustion engine, the air damper opens.
- In the diffuser (16), where there is a constriction, the air flow is accelerated and mixed with the gasoline. The latter enters through the nozzles (15) and (12), and the air purified by the air filter through the damper (7) located at the diffuser inlet.
- The damper (8), located behind the diffuser, regulates how much of the prepared mixture enters the combustion chamber.
- The volume of gasoline passing through the jets is regulated by screws (17) and (10). these are, respectively, screws L and H on the chainsaw.
- The needle valve (11) determines the volume of the fuel mixture in the float chamber (14). The functioning of the needle valve is controlled by a diaphragm (13).
- The membrane (4) controls the flow of the fuel mixture into the combustion chamber, and this depends on the number of revolutions of the internal combustion engine. Gasoline is cleaned through a filter (6).
Adjustment and troubleshooting in the operation of the chainsaw carburetor
The functioning of the internal combustion engine (ICE) of a chainsaw is based on the combustion of a fuel-air-oil mixture. To mix the gasoline-oil mixture with air, and then feed it in portions into the combustion chamber, a rather complex device is installed on the engines. a carburetor. When buying a new chainsaw, the carburetor already has factory settings, but over time they get lost, and the device that controls the fuel supply needs to be adjusted again. Not knowing how the carburetor works, and not understanding the principle of operation of this module, it will be problematic to correctly configure it.
When adjustment is needed
As already mentioned, the new chainsaw already has standard fuel settings. But for proper break-in, it is recommended to limit the maximum engine speed, and this is done using the adjusting screws located on the carburetor body. Also, after running in, you will need to make a more accurate adjustment of the fuel mixture supply again.
In addition, you will have to adjust the carburetor in the following cases:
- due to strong vibration, the factory settings are lost;
- The internal combustion engine does not start well and immediately stalls;
- The internal combustion engine starts up, but the speed does not develop, and it stalls;
- the piston group has worn out. in this case, adjusting the carburetor of the chainsaw is possible as a temporary measure;
- the engine does not function at idle;
- increased gasoline consumption, due to which the unit emits a lot of smoke, the muffler and spark plugs become dirty with carbon deposits, the engine power decreases.
Carburetor tuning rules
You should be aware that the carburetor can only be properly adjusted if:
- cleaning filters (gasoline and air) are not contaminated;
- the jets and the channels that fit them are clean;
- membranes are not damaged;
- the needle valve is in good working order and the required volume of the fuel mixture enters the float chamber.
To adjust the carburetor of imported chainsaws, you must adhere to the following rules.
- Before adjusting, if possible, warm up the engine at idle or minimum speed for about 10-15 minutes.
- By rotating the “L” regulator, the engine is working so that it produces at idle one and a half to two thousand revolutions per minute. But you should pay attention to how the engine picks up speed. When pressing the throttle lever, acceleration should go quickly and evenly. If a “dip” of revolutions is detected, the screw should be slightly unscrewed until this phenomenon is eliminated, since it is caused by insufficient enrichment of the fuel mixture.
- When the mix is adjusted at low speed, start tightening the “T” screw until you notice the saw chain turning. After that, the screw should be unscrewed by half or a third of a turn, observing the behavior of the clutch mechanism. Normally, the saw should not rotate at idle speed.
The screw “H” compensates for underspeed or overspeed due to a change in the type of fuel, changes in oil concentration or humidity of the ambient air.
Also, the “upper” setting can fly off if the low speed is incorrectly adjusted with the corresponding screw.
Screw “H”, not having enough experience, it is better not to adjust. If the tuning of the carburetor of the chainsaw is carried out by an incompetent person, there is a great danger that a too lean mixture will enter the combustion chamber at high speeds, especially under load. Such operation of the engine will inevitably lead to rapid wear of its piston system and to a failure in the ignition system.
It is possible to start adjusting high revs if the person who will perform the tuning has the knowledge and skills in adjusting carburetor engines. The master-tuner must have a special device at his disposal. a tachometer or a multimeter with an oscilloscope function.
Setting up the carburetor of a chainsaw, namely, high engine speed, follows a simple scheme.
- It is necessary to tighten or unscrew the screw “H” until at maximum gas the engine develops about 15 thousand revolutions per minute (according to the tachometer) or the value that is indicated in the manual for this unit.
- When using an oscilloscope, the spark discharge frequency should be between 230 and 250 Hz. It should be borne in mind that under load, the frequency can decrease by approximately 10-15%.
It can be concluded that for safety, the internal combustion engine should be tuned to slightly lower rpm.
The carburetor of a Chinese chainsaw should be adjusted in the same way as described above. There are holes on its body, into which, in order to adjust the engine speed, you need to insert a flat screwdriver. Each hole is labeled with one of the three letters. As a rule, you can see the letter “T” near the upper hole, and the letters “L” and “H” near the lower ones (shown by arrows).
The Chinese chainsaw Carver (CARVER) has the same arrangement of screws. The following figure shows what the carburetor from a Chinese chainsaw looks like outside the body of the unit.
How to troubleshoot a carburetor
The main malfunctions of the chainsaw carburetor may be as follows.
- The engine starts with difficulty and stalls a few seconds after starting. This is often caused by an incorrect low speed setting. The fuel-air mixture is poorly enriched. It is necessary to unscrew the screw “L” by half a turn, after which the adjustment should be completed with the screw “T”.
- The engine power is noticeably reduced under load. This means that the carburetor is over-oxygenating the mixture. Therefore screw “H” needs to be tightened a little, about 1/8 of a turn. If, after such actions, the engine power is still insufficient, but there has been some improvement in its operation, then the regulator can be tightened a little more.
- The engine at maximum speed and without load begins to “sing”. This malfunction of the unit is caused by a lean mixture and overestimated speed. Adjustment takes place with the same screw “H”.
- No gasoline enters the combustion chamber. Breakage can be caused by clogged fuel filter, carburetor passages and jets. To eliminate the malfunction, you need to completely disassemble this chainsaw module and purge its channels with compressed air (you need a compressor). To properly clean the fuel channels, you can use a special carburetor flushing fluid. Also, the lack of fuel flow into the engine cylinder may be due to improper adjustment. How to do it yourself, was discussed above.
- Overflows the carburetor. In 90% of cases, fuel overflow is caused by a dried and hardened membrane, which presses on the rocker arm associated with the needle. To change it, you will need to remove and disassemble the carburetor.
- The engine picks up speed poorly, runs intermittently, and decreases power. These problems are often caused by a clogged air filter. You will need to remove the cover that covers the filter and clean it, which consists in washing with detergent.
In general, timely adjustment, as well as timely repair of the chainsaw carburetor, can significantly extend the life of the entire piston system of the engine. Therefore, the tuning of this component of the fuel system must be treated with great care.
Carburetors used on Chinese chainsaws
Well-known brands develop the best models that are almost impossible to copy, which is why most of the Chinese manufacturers make the most popular models. Some remain without a name and labeling, others receive the names of popular brands.
The peculiarity of the carburetor depends on the model and power. Due to this, the dimensions of the carburetor and their design differ from each other.
Most of the copies are similar in design to the originals, but alas, the quality is rare. Today, not all products made in China can be considered junk.
According to the quality of the carburetor, it can be divided into three types:
- average cost;
Cheap, most often made of second-class materials, which often break, do not converge in fit, crumble, the size of the holes does not converge with the calibration, the thread breaks. Such carburetors are hard to even call disposable. I am buying such a carburetor, let us be aware that you just threw your money down the drain, because such a purchase does not even have a marking and model name.
Mid-range carburetors are ideal factory-built and good quality carburetors. Perhaps such a carburetor will work longer than the chainsaw itself.
Branded carburetors are made in China, but they differ from Chinese ones only in that they have a name and their own brand. Firms that make such carburetors value their reputation and invest in manufacturing power.
Adjusting the carburetor of a Chinese chainsaw
Adjusting the carburetor of a Chinese chainsaw
This feature is not available on all Chinese chainsaw carburetors. Today, there are many models for household use that do not have adjustment screws, even in European ones. Well, if there is, then it is one, and is provided for adjusting the idle speed.
These carburetors only need to be adjusted when the saw periodically stalls at low RPM. In order to adjust the carburetor, you need a screwdriver that fits the bolts.
Keep in mind that on some carburetors they can be cross-shaped, on others flat, on others hexagonal, an asterisk, and so on. To check, you still need a tachometer, if you do not have one, then check by ear.
Chainsaws made in China receive factory settings, which rarely fail. Therefore, make sure to adjust the saw and not the carburetor. It so happens that a new carburetor needs adjustment and very rarely an old one.
- Bad fuel. A clogged muffler, exhaust windows, or balloon can cause poor engine performance.
- If, after checking these reasons, the engine does not change, then proceed to adjust the carburetor.
- Each model has different access to the adjusting screws. On some models, access can be obtained immediately, on others, you first need to remove the cover or part of the case. The T screw (on some models it is designated LA) regulates the idle speed, the L screw regulates the fuel quality. Screw H is the main screw, it regulates the amount of fuel delivery.
- To do this, you must first warm up the engine. In no case do the check on a cold engine, this will give incorrect readings.
- Each chainsaw comes with a manual that states the maximum number of revolutions, most of which reach 2500 idle revolutions. Determine them using a tachometer. If the saw does not develop speed well, then the engine does not have enough fuel, screw H is responsible for its supply. Unscrew it by one quarter of a turn, if it starts to work better, tighten it again. If, on the contrary, the engine performance has deteriorated, tighten the screw back, then there is too much fuel supply.
- After checking the amount of fuel, it is necessary to check the quality using screw L. Unscrew it in the same way as screw H, by one quarter and check the speed from low to high and the amount of air in the mixture. If there is little air, fuel will not burn out and this will lead to engine smoke. Then it is necessary to unscrew the bolt another quarter of a turn. The adjustment of the screw L can be completed when the speed from low to high will pass smoothly and the engine will no longer smoke.
- If screw L, unscrew more screw H, the piston may fail. Due to the fact that there will be little gasoline, and there is a lot of piston air, dry and very hot, do not allow this.
- It also happens that after adjusting two screws, it may be necessary to adjust the third screw T, which is responsible for idling.
- To adjust idle speed, warm up the engine for 6-8 minutes. To start the chain, unscrew the screw T and increase the speed. When the chain starts to move, tighten the screw back.
When choosing a carburetor, you need to confidently navigate in them and when resorting to a purchase, it is better to opt for an average price policy.