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.
So let’s get started!
- First, an annotation on the operation of the device itself.
- Secondly, the tachometer. Why exactly does it come in handy to us, we will discern a little later.
- B-3. screwdriver.
Surprisingly, this is all we need.
To get started, carefully familiarize yourself with the design of your saw. What you need to do first is find where the carburetor jets are, and even more important than the jets, the adjusting screws. Usually, there should be two to three screws. One of them regulates idle speed, and the other two. low and high.
Specifically, they will need to be adjusted for you, or twisted, or unscrewed in order to enrich or deplete the fuel mixture.
If you need to deplete the mixture, then simply turn the regulator clockwise, if you enrich it, then accordingly.
To adjust the idle speed, the screw, which is responsible for this, also needs to be either turned clockwise in order to increase the speed, or, as you already thought of, in the opposite direction to decrease them.
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 transitions into 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.
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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 more air flow, which means more fuel flow. 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.
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.
Adjusting the Carburetor of the Husqvarna Chainsaw 137
Description of the adjustment process for Husqvarna chainsaw carburettors. The main obstacles that can be solved with the option of the property and the amount of fuel.
Modern chainsaws have a complex system and consist of several main units, which at times require maintenance and adjustment. In this article, we will talk about how to adjust the carburetor on a Husqvarna chainsaw.
Chainsaw: do it yourself carburetor adjustment
To self-adjust the carburetor, you need to familiarize yourself with its device and remember the operating procedure that is performed to adjust the parts responsible for the correct functioning of the component parts of the device and the parts adjacent to it.
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 poorly 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. adjustment.
How to properly adjust the carburetor on a chainsaw with your own hands?
A chainsaw is a useful, and sometimes just a necessary tool for the owner of a private house. It has a high degree of autonomy, can be used in the field, where there is no possibility of connecting to the power supply network. For some craftsmen, the chainsaw is one of the main devices that perform large amounts of work almost daily. Such loads knock down the factory settings that were set for all important engine components.
The operating mode most often changes with the carburetor, which has to be re-adjusted. Not having an idea of the design and principle of operation of this element, it is impossible to properly adjust it. The question concerns many users who closely operate chainsaws, so it will be useful to consider it more carefully.
To tune the carburetor, you will need a Phillips or slotted screwdriver of different lengths or thicknesses; the size depends on the design of the unit and the assembly of the engine. It should be noted that some manufacturers make carburetors designed to use special tools.
In particular, special types of screwdrivers may be required to tune Husqvarna carburettors and other imported tools. It is advisable to clarify this question even when buying a chainsaw, so that you can purchase the necessary additional equipment in advance.
In addition, you will need refined gasoline or acetone to flush and clean the device. They are used to clean the outer surfaces of the carburetor. All internal channels are flushed with kerosene, diesel fuel or white spirit. Before flushing, the carburetor is disassembled, all rubber or plastic parts that may suffer from contact with aggressive chemical compounds are removed.
Open-end or spanner wrenches are used to disassemble the carburetor. The internal channels are flushed in specially designated trays, sometimes plastic syringes are used for this.
How to properly adjust the carburetor with your own hands?
After rinsing and completely cleaning the carburetor, assemble it and begin to adjust. First of all, you should understand the purpose of the adjusting screws. The instruction will help with this, but some general points should be considered right away. The most common designations for screws are:
- H. adjusts the state of the main jet, i.e. adjusts the maximum speed of rotation of the motor shaft;
- L. adjusts the idle jets (responsible for the minimum shaft rotation speed);
- T. regulates the idling of the motor. It can also be designated by the letters LA or S, on some models of carburetors it is not at all.
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 idling 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 the chainsaw. Then you need to prepare the workplace. lay the saw on a flat horizontal plane, directing the chain in the opposite direction from you. Detach all covers, remove foam rubber and air filter. At this, the preparatory operations are considered completed, you can proceed to the main part of the work.
- Smoothly tighten the screws H and L clockwise until they stop. Be careful not to break the screws. this will cause a complete loss of the carburetor.
- Unscrew both screws one and a half turn.
- Run the engine for 10 minutes and warm it up. This is a necessary moment, since it will not be possible to correctly adjust the carburetor on a cold engine.
- Turning the screws H and L, alternately adjust the rotation of the shaft at maximum and minimum revolutions.
- 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 idling or not. If it moves, turn the screw a little more counterclockwise.
Important! It is better not to adjust the screw H for an inexperienced person. If it is not set correctly, a lean air-fuel mixture will be supplied to the combustion chamber of the cylinder at maximum speed. This will lead to accelerated wear of the piston group.
You can check the operation of the engine visually and by ear. A mixture that is too rich will cause thick smoke from the exhaust. When the lean mixture is being fed, a whistling sound is heard while the saw is running. Excessive economy mode is harmful. if the L screw is set to “lean” fuel, there will be problems with starting the engine. If the H screw is set to lean, the saw will noticeably lose power. You can determine the correct setting by the following criteria:
Carb Adjustment on The Chinese Chainsaw
- at idle speed, the engine does not stall, and the chain is stationary;
- there is no excessive smoke from the exhaust pipe while the engine is running;
- the engine demonstrates good throttle response (quickly picks up speed when you press the accelerator).
A detailed description of the setting is available in the instructions that come with the instrument in the delivery set. It should be carefully studied, as there may be some features or specific requirements established 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.
When carburetor adjustment is necessary?
Initially, from the moment the tool was sold, all carburettors were adjusted and tuned at the factory. However, in the process of operation, the settings gradually go astray, and the operating mode changes in accordance with the operating conditions. Signs of a carburetor malfunction may include:
- too high gasoline consumption, thick smoke comes from the exhaust pipe;
- engine power is clearly not enough to perform normal tasks;
- engine speed “float”;
- after starting, the motor stalls either immediately or after a few seconds;
- the engine cannot be started at all;
- the chainsaw “shoots”, there are sharp claps in the engine of the tool.
Note! The reason for poor engine performance may be the worn out piston group, then adjusting the carburetor of the chainsaw does not give a full solution to the problem. Also, no setting will give the expected effect if the node is not cleaned of small particles of debris in parallel. The most problematic elements are jets and filters, both gasoline and air.
It should be noted that during the running-in of a new engine, the carburetor is adjusted to a reduced fuel supply in order to limit the engine power. After the end of the run-in, the fuel supply increases to the nominal value. These adjustments are made using the adjusting screws on the carburetor body (there are usually two or three of them).
Design and principle of operation
A carburetor is a device in which fuel (gasoline) and air are mixed in predetermined proportions, followed by feeding the prepared mixture into the engine cylinder. Almost all models of chainsaws are equipped with carburetors of the same type, so the device and principle of operation are the same.
The main structural elements of the carburetor are:
- body, which is cast from aluminum to reduce weight. Chainsaws constantly have to be moved from place to place, during operation they are held by hands, therefore, reducing the weight of the tool is the primary task of manufacturers;
- a diffuser with an air damper, which are located at the inlet;
- jets, which are valves for metering fuel;
- a sprayer that injects gasoline into the chamber (in the diagrams it is designated as the main jet);
- fuel (float) chamber.
Figure 1. Diagram of a chainsaw carburetor
The principle of operation of the carburetor can be described as a cycle consisting of the following steps:
- When starting the engine, the choke opens.
- The piston stroke creates a vacuum in the air channel, as a result of which air enters the diffuser, the amount of which is regulated by the position of the air damper.
- Gasoline flows from the gas tank to the float (fuel) chamber. The rate of its admission is regulated by jets.
- In the diffuser, gasoline and air are mixed, resulting in the formation of a fuel-air mixture, which then enters the engine cylinder. The more the mixture enters the combustion chamber of the cylinder, the higher the power and speed on the engine shaft will be.
Important! It should not be assumed that the operation of the carburetor has a cyclical basis, as it might seem from the description. All processes take place constantly and continuously.
How to set up a China-made saw?
The design of the carburetor on Chinese chainsaws is no different in principle. The order and principle of adjustment also do not differ and are performed in the same order. The only difficulty that may arise during the execution of work is determining the purpose of the adjusting screws. Typically the T screw is at the top, while the H and L are at the bottom of the carburetor body. One more, additional screw may be present.
Figure 3. Location of adjusting mechanisms
Usually, their purpose is determined empirically, slightly changing the position and monitoring the result. After the purpose of the elements is clearly defined, further customization is not difficult and is performed in the usual manner.
Chainsaw carburetor tuning is an important and necessary procedure that must be performed periodically to restore the normal operation of the tool. This process does not create fundamental complexity, but it requires the user to be careful, attentive and comply with safety rules. The chain of a chainsaw is usually not removed, since you will need to observe its position. Therefore, it is important to constantly remember about the possibility of launching it and exercise the necessary caution.
The adjustment should be done smoothly, with small changes in the position of the screws, so as not to cause too sharp changes in the shaft rotation mode. The result depends on the care and thoroughness of the user, and a properly tuned carburetor will extend the life of the tool.
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What to do if gasoline does not flow into the chainsaw carburetor?
The first of the reasons for this breakdown is the clogging of the fuel filter with dust and dirt. This happens due to the presence of a large amount of harmful impurities in gasoline and used engine oil. Over time, they accumulate on the surface of the filter, due to which it loses its ability to pass fuel. To solve the problem, you will need to thoroughly clean the filter by rinsing it in a bath with a cleaning agent. If the filter has holes or other signs of wear, it must be replaced immediately.
The second cause of breakdown is contamination or breakage of the tube through which fuel is supplied to the carburetor. If the hose is not cut off, it will be enough to thoroughly blow it out with compressed air from an aerosol for cleaning. If the tube is broken, it will need to be replaced. When installing the hose, the places of its joints with the fittings must be carefully treated with a sealant.
There is another malfunction that occurs much less frequently than the previous two. It consists in a breakdown of the valve that regulates the rate of fuel supply to the carburetor. If dust or small chips get inside its mechanism, then the flap is blocked and remains in the closed position. Repair of the assembly can only be performed with the replacement of the damper, since it, most often, cannot be restored.
Carburetor Tuning: Highlights
Reassembly of the carburetor is carried out only after complete cleaning, drying and blowing with compressed air. At the same time, do not forget that some gaskets and seals, even if there is no damage, must be replaced.
You can start adjusting the carburetor provided it is correctly troubleshooting, high-quality assembly and flawless re-installation on the engine.
Carburetor setting principles:
- screws H and L adjust the ratio of air and combustible mixture, i.e. throttle position. Tightening the screws clockwise leads to a depletion of the mixture and the transition of the engine to low rpm. When unscrewing (counterclockwise), the mixture is enriched, and the engine speed increases;
- screw T is responsible for adjusting the idle speed: turning it clockwise gives an increase in their number, against. a decrease;
- screws are adjusted in L-H-T order.
The general adjustment algorithm looks like this:
- Initially, the highest idle speed is found by turning the screw L and then returning it by ¼ turn counterclockwise. If the chain rotates at idle speed, turn the screw T in the same direction until it stops completely.
- With the engine warm, running at full speed, turn the screw H by ¼ turn to the left, then let the engine run for 10 s, check the maximum speed using a tachometer. It must correspond to the number indicated in the instrument’s passport.
- After calibration with screws L and H, using screw T, idle speed is set. If done correctly, the engine will run evenly in all positions.
Memo for calibrating the carburetor on the body of the chainsaw
Upon completion of the adjustment, it remains to reinstall the cover of the chainsaw with an insulating gasket, after which you can start the main work. If the settings are correct, the chainsaw engine will get the optimal fuel mixture. This will ensure its normal efficiency, as well as the overall comfort and safety of working with the tool.
How to properly adjust the carburetor on a chainsaw?
Before adjusting the carburetor on a chainsaw, you will need to study the meaning of the three screws required for adjustment. These screws have specific markings and names:
- The “L” screw is needed to adjust the low speed;
- The “H” screw is required when tuning the motor for high speed operation;
- Screw “T” is needed to adjust idle speed.
It is worth noting that some chainsaws are equipped with only one “T” screw, so the carburetors of such models are adjusted by manipulating only this screw.
No matter how many screws there are on the chainsaw, the factory settings of the carburetor are the most optimal for its operation. The screws themselves were originally used to adjust the chainsaw to work in certain weather conditions.
Chainsaw carburettors with three screws should be adjusted using screws “L” and “H”. To increase the speed, they should be turned clockwise. In order to reduce the speed, the screws turn against it. To adjust the carburetor, you need a special screwdriver for adjustment. it will not slide off the screws and damage the threads on their “caps”.
The carburetor adjustment process consists of two stages: initial and main. The algorithm of actions during adjustment is as follows:
- During the first step, screws “L” and “H” must be tightened clockwise to the very end;
- After that, these screws must be turned 1.5 turns in the opposite direction;
- At the second stage, you need to start the chainsaw and leave it for 10 minutes to fully warm up;
- Then start turning the screw “T” until the chainsaw motor starts to run stably and the chain on the bar does not rotate.
Do not rush when adjusting your chainsaw. It must be remembered that the slower you turn the screws, the better you will feel the changes in the tool’s motor.
The device and principle of operation of the chainsaw carburetor
The task of the carburetor is to prepare a mixture of gasoline and oxygen and feed it into the cylinder in doses. Mixing takes place in the diffuser (16). the converging part of the carburetor, where the air flow is accelerated. Gasoline of various fractions (coarser and finer) and purified air after the air filter enter the diffuser through 2 nozzles (15) and (12). Its amount is regulated by the air damper (7) at the diffuser inlet. The amount of the finished mixture supplied to the cylinder is regulated by another flap (8), which is behind it.
Two screws (17) and (10) (L and H) regulate the amount of gasoline passing through the jets. The amount of gasoline in the float chamber (14) is regulated by a needle valve (11), the operation of which is monitored by a membrane (13). The second diaphragm (4) doses the amount of fuel supplied to the chamber depending on the engine speed. On the way, it is filtered through a filter (6).
If both filters, air and gasoline, are clean, the channels and nozzles are not clogged, the membranes are intact, and the needle valve reliably regulates the amount of gasoline in the float chamber, then the carburetor is working properly, and for normal preparation of the mixture it is necessary to correctly adjust the amount of gasoline supplied through the nozzles. We will not talk about mechanical wear of metal parts of the body and valve rods of the carburetor, because it will be cheaper to simply replace it than to repair it.
How to adjust the carburetor on chainsaws
To understand how to properly adjust the carburetor on a chainsaw, you need to see it, and therefore we invite the reader to pay attention to the example below.
To make the adjustment, you only need a slotted screwdriver, however, it will not be possible to perfectly fine-tune the carburetor without a tachometer (of course, if the person is not a minder or a professional driver with experience). Now let’s try to understand how to set up the carburetor in a given situation.
How does a chainsaw carburetor work, on what principle does it work
Modern car engines are no longer equipped with a carburetor. Meanwhile, before, almost every driver knew how to adjust it. Today, chainsaws with injection engines have already begun to appear on sale, however, carburetor models will hold the palm for a long time, because their cost is 5-15 times lower than that of the modernized version.
The carburetor consists of several main parts:
- aluminum body;
- diffuser and air damper at the inlet;
- nozzles (valves for adjusting the fuel supply);
- atomizer (it is he who provides injection);
- fuel (float) chamber.
The principle of operation of a chainsaw carburetor is quite simple. Fuel is supplied continuously, and its quantity is regulated by jets. Air enters through the air damper due to the air vacuum generated by the piston. The diffuser mixes fuel and air. It is this fuel-air mixture that enters the cylinder, forcing the engine to work.
Determining the need to adjust the carburetor on a chainsaw
Before you start adjusting the carburetor on a chainsaw, you need to make sure that it is generally required. It would seem an absurd phrase. However, in 90% of cases, when an inexperienced craftsman considers such an action necessary, the unstable operation of the instrument is associated with other reasons, including:
- problems in the fuel lines and filter. blockages, depressurization;
- malfunction of the exhaust system;
- clogged or damaged air filter;
- unstable operation of the ignition system;
- violation of the tightness of the internal combustion engine crankcase.
Only if these problems are excluded, and the engine is unstable, it is safe to say that carburetor adjustment is required.
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How to set up a chainsaw carburetor if it won’t start at all
Quite a common problem in those cases when the “master” from the “I know everything” series tries to get into the settings with hands that do not grow from the shoulders. In this case, there are standard screw positions from which you can “dance” further. First, you need to completely tighten both screws (do not overdo it). Then unscrew:
- screw L. one revolution;
- screw H. one and a half turn.
With regard to the idle screw, the throttle must first be completely closed (screw T removed). After that, it must be cranked one and a half turns clockwise and try to start the engine. If it did not work out, it is gradually added by a quarter of a turn before starting. When the engine starts to work, the position of the idle screw is adjusted so that the internal combustion engine does not stall, but the chain is still in place.
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Mechanic at home: adjusting the carburetor of a chainsaw with your own hands
Any internal combustion engine requires periodic maintenance, It doesn’t matter if it is the engine of a simple moped or a powerful multi-ton tractor. Such a tool as a chainsaw was no exception. After all, it is equipped with a single-cylinder two-stroke internal combustion engine, which also requires serious maintenance, although it is much easier to perform the necessary actions here. In today’s article we will talk about how to adjust the carburetor of a chainsaw with our own hands, find out how difficult it is, and figure out whether you need to be a professional mechanic to do this kind of work.
How to correctly and accurately adjust the carburetor: step by step instructions
In order to make the information easier to perceive, we propose to consider it on the basis of photo examples with a description of actions in tabular form. Chainsaw with initial settings is taken as a basis.
You can learn more about the master class on adjusting the carburetor of a chainsaw in this video.
2) Factory setting of needles
Lower needle: 1 1/4 turns from fully closed position Upper needle: 1 3/4 turns from fully closed position Note. This factory setting is very important. Before starting the engine for the first time, make sure both needles are in the factory positions.
5） Start break-in, which is vital for gasoline engines.
After confirming stable hovering while rotating the main rotor at 1400-1500 rpm, start the run-in process, consuming 2-3 liters of fuel. The further you continue to run in, the more the engine will run.
Chainsaw carburetor speed adjustment
Lower needle adjustment rich
When you open the throttle for takeoff, the engine speed does not increase due to the large amount of white smoke coming out of the exhaust pipe.
Solution → Rotate the Low needle slightly (say 6 degrees) clockwise and try to take off again. Each adjustment should not exceed, say, 6 degrees. Gasoline engine carburetor needles are much more sensitive than glow.
Do not touch the high speed needle until the low speed needle adjustment is complete. ＊
Final check at idle speed
Before this procedure, it is necessary to perform a full adjustment of the components of the carburetor when operating at maximum speed. Next, you should check the functioning of the device in idle cold mode. When the correct parameters are achieved during the adjustment, you will notice that the carburetor design exactly matches the following criteria:
When the idle cold mode is connected, the chain does not move.
If violations are noticed in the above parameters or the device was not completely adjusted, you need to perform the main setup step again. Sometimes actions are performed incorrectly. In this case, the device may fail due to the loss of the correct node settings. In this case, you will have to contact a specialist.
In order for the chainsaw to work properly, you need to carefully perform work on adjusting the carburetor in exact accordance with their sequence. If there are any irregularities in the operation of the device, it is necessary to completely disassemble it yourself. In most cases, it is necessary to replace any parts that have become unusable.
With a constant check of the quality of carburetor settings and the implementation of timely actions to improve its operation, problems with the chainsaw do not arise.
About which chainsaw to choose. read here.
What does a chainsaw carburetor do?
Chainsaw carburetor is quite simple, like carburetors, but not devoid of subtleties. Purpose of the carburetor. precisely control very small quantities of fuel and mix it with the air entering the engine to keep the engine running properly. When not enough fuel mixes with air, the fuel becomes lean and the engine either does not run or can be damaged. A lean mixture is caused by a lack of fuel or too much air. Typically, in a two-stroke engine such as a chainsaw, fuel also provides engine lubrication. When excessive fuel / air mixing occurs, the engine will “run rich” or be flooded with fuel and may not start, or it will run and give off a lot of smoke, or it will run poorly so that it stalls and swamps easily, or even wastes fuel. Chainsaws that run on a lean or rich mixture will emit excessive exhaust. This way, a chainsaw that works properly will have the correct fuel-to-air ratio, a healthy spark, and a sufficient compression ratio to heat the air-fuel mixture. The carburetor is responsible for the correct air / fuel ratio for the mixture. To find spare parts for carburetor and other chainsaw parts CLICK HERE
The carburetor in a chainsaw is relatively simple compared to other carburettors as it only needs to work in these three situations;
- If you are trying to start a chainsaw in a cold state.
- While the chainsaw engine is idling.
- When the chainsaw engine is wide open.
Few people who work with a chainsaw are really interested in the gradation between wide open throttle and idle, so the ramps between these extremes don’t really matter. However, for larger engines such as a car engine, multiple gradations are important, making the car’s carburettors much more difficult.
Chainsaw Carburetor Adjustment | How to Tune ‘Correctly’. by Craig Kirkman
The chainsaw carburetor has the following main features; First, the carburetor. it’s generally a tube. Across this tube is an adjustable circular plate known as a choke valve. Inside this tube, at some point, there is a constriction known as the Venturi. A vacuum is created in the Venturi. There is a hole inside the facility known as a jet. which allows the vacuum to suck in fuel.
When the carburetor is operating normally at full throttle. The throttle valve is usually parallel to the length of the tube to maximize air flow through the carburetor. The air flow creates a vacuum inside the nozzle that sucks in a controlled amount of fuel through the nozzle.
When the engine of a chainsaw is idling, the throttle valve is often almost closed, in which case there is not enough air through the ventilation device to create a vacuum. However, there is a vacuum on the back of the throttle body as the plate obstructs air flow. If you drill a tiny hole on the side of the carburetor tube, the throttle valve can suck air into the tube. The tiny hole is known as a blank jet. There is another screw labeled “Lo” or “L” that adjusts the amount of fuel flowing through the idle jet.
When you try to start a wire rope saw on a cold engine, it runs at extremely low RPM, and the engine is cold and therefore requires a very rich air / fuel mixture to start. The throttle valve now comes into play. When activated, the plate covers the venturi. When the venturi is closed and the throttle is wide open, the carburetor engine draws in a lot of fuel through the main jet as well as the idle jet. The result is a very rich mixture that allows the engine to start once or twice, or just run slowly. Now, if the choke is open, the engine starts to run normally.
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-enriching the mixture with oxygen. 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, 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 power decreases. 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.