How To Put A Carburetor On A Chainsaw
When carburetor adjustment is required
If it happens that the adjusting screws are loosened, then the carburetor should be adjusted. Other signs may indicate the need for these manipulations, among them:
- Breakage of the protective cap;
- Significant piston wear;
- Interruptions in the operation of the motor;
- Strong vibration;
- No response from the engine when trying to start the tool;
- Increased fuel consumption;
- Strong exhaust.
Basic adjustment step
First you need to use the rotational screws. They are wrapped clockwise all the way. Then turn it back one and a half turns.
In order to get to the carburetor, the bolts on the tool cover are unscrewed. The case must be opened and the foam rubber, and parts of the air filter must be removed. Only now can you start adjusting. Before setting up the carburetor on a chainsaw, you should find out that the main task of these works is to change the amount and quality of the air-fuel mixture that is pumped into the engine combustion chamber.
While working, you must follow certain rules, among them:
- The chain must be directed to the side;
- Place the equipment on a flat surface;
- Cutting parts must be removed to a safe distance.
The first requirement is due to the need to avoid injury. If you are wondering how to set up a carburetor on a chainsaw, you should know that it is necessary to carry out these works using three screws. The first of them controls the jet and is designated by the letter “H”. It is necessary to correct the maximum speed.
The second screw can be found under the letter “L”. This assembly is required to control the idle jet at low shaft speeds. Quite often, novice craftsmen ask themselves how to set up a carburetor on a Partner chainsaw. It denotes the third screw with the letter “T”. It is needed to correct the idle speed. The adjustment process is divided into stages:
The first is carried out with the engine off, while the second is carried out with a warm engine.
The nuances of adjusting the carburetor of the Stihl MS 250 chainsaw
You may have a question about how to adjust the carburetor on a Stihl chainsaw. First you need to decide when such a need arises. The work described may be required if the spark plug electrodes have changed color. When it turns out to be black, this indicates over-enrichment, while with a brick-gray color, you can be calm, since this is the norm. When a master notices a white bloom, then he can be sure that the mixture is depleted.
The upper screw plays the main role in the adjustment; it is located closer to the muffler in the described model. If you follow the factory parameters, which you can find on the tool cover, then this screw must be unscrewed one turn, and then corrected. When unscrewing, the mixture will be enriched, while if the screw is screwed in, the mixture will be leaner, while less gasoline will enter the air-fuel mixture.
Correction of the maximum number of revolutions
Before adjusting the carburetor on the Partner 350 chainsaw, you must find the screw “H”. It is required to adjust the maximum speed. It should be rotated clockwise, while if it is necessary to reduce the number, then the movement of the screw should be directed in the opposite direction.
The maximum frequency should be set between 11500 and 15000 rpm. If this value is exceeded, then the engine will work for wear, which will certainly lead to a malfunction during ignition. When turning the screw under the letter “H”, you need to take into account how the ignition occurs. If malfunctions occur, then the rotation should be stopped by turning the screw counterclockwise.
If piston wear has occurred, then it will be necessary to repair the engine as well, but adjusting the carburetor will act as a temporary measure, while the unit will work more stably. If the described unit turned out to be clogged, which led to interruptions in the operation of the motor, then it will also be necessary to flush.
Whereas when a situation arises when the engine stalls or does not start, it can be concluded that the working mixture was depleted. Incomplete combustion of the fuel mixture is also indicated by the abundant exhaust. This conclusion can be reached if the tool began to consume excessive amounts of fuel.
How to set up a carburetor on a chainsaw: recommendations
Chainsaw carburetor. This is one of the main components of this tool. He is responsible for the fuel supply. The efficiency and power of the equipment depends on how correctly this unit functions. Timely adjustments are also economical.
Before adjusting the carburetor on a chainsaw, you should know that adjustments to this part of the device are quite rare. Typically, the factory setting is sufficient for normal operation. However, if a more precise adjustment is required, then special screws can be used. Before starting such work, you need to understand the subtleties and nuances of the process.
You should know how to adjust the carburetor on a Chinese chainsaw. In this case, another check is carried out at idle speed. Once the acceleration adjustment has been completed, the tool must be brought to idle. If you did everything correctly, the chain will remain stationary, and the motor will pick up speed in a short time when you press the accelerator.
You should also listen to the operation of the engine. The sound should be like a four-stroke unit. If you are thinking about how to properly tune the carburetor on your chainsaw, you must take care that the above conditions are met. If this is not the case, then the adjustment must be repeated, while the basic stage is omitted. You should not take to work if you do not have sufficient experience, because in this case, misalignment of the unit may occur. When self-tuning is not possible, then stable work can be achieved by contacting professionals.
Before adjusting the carburetor on a Husqvarna chainsaw, you need to find the third screw, which is marked with the letter “T”. The engine then warms up for 10 minutes at medium speed. The third screw must be turned counterclockwise until the motor starts to run steadily. The chain must be stationary.
If the engine stalls at idle, the screw should be turned clockwise. When the target moves, the screw is unscrewed back. If you are faced with the question of how to set up the carburetor on a chainsaw, the next step is to check how the engine works correctly at maximum speed when accelerating. It should be assumed that the engine is operating correctly under acceleration if the accelerator is pressed to a maximum RPM between 2800 and 15000. The screw marked “L” must be unscrewed to the left one eighth of a turn.
When is carburetor adjustment 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:
- Fuel consumption is too high, thick smoke comes out of the exhaust pipe;
- The engine power is clearly not enough to perform normal tasks;
- Engine speed “floats”;
- 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 tool engine.
It should be noted that during the running-in of a new engine, the carburetor is set 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 (usually two or three).
How to properly adjust the carburetor on a chainsaw with your own hands?
A chainsaw is a useful, and sometimes simply 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. Without understanding the design and principle of operation of this element, it is impossible to properly adjust it. The question concerns many users who operate chainsaws tightly, 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 this unit and the features of the engine assembly. It should be noted that some manufacturers make carburetors designed to use special tools.
In particular, special types of screwdrivers may be required to adjust 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. Internal canals are washed in specially designated trays, sometimes plastic syringes are used for this.
Design and working principle
A carburetor is a device that mixes fuel (gasoline) and air in specified 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:
- The 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 located at the inlet;
- Nozzles, 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 the carburetor can be described as a cycle consisting of the following steps:
- Air damper opens during engine start.
- 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.
- Gasoline and air are mixed in the diffuser, 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.
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 rotational speed 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 during adjustment). 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.
Carburetor adjustment procedure:
- 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 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.
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:
- At idle, the engine does not stall, and the chain is stationary;
- When the engine is running, there is no excessive smoke from the exhaust pipe;
- The engine demonstrates good throttle response (picks up speed quickly 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 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.
How to set up a China 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 work is determining the purpose of the adjusting screws. Typically the T screw is at the top and the H and L are at the bottom of the carburetor body. One 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 carried out in the usual way.
Chainsaw carburetor tuning is an important and necessary procedure that must be periodically performed 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 must 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.
Modification of the Ural chainsaw carburetor: we eliminate factory defects
Since the KMP-100 carburetor was the only one produced in the USSR, several million of them were produced. With such a mass and long-term production, the product could not be raw and unfinished. All the shortcomings were taken into account, finalized already at the beginning of production, and the factory, design and technological, KMP-100 and KMP-100U had no shortcomings.
The KMP-100U carburetor requires improvement when the engine from the Ural 2t Electron chainsaw is used for another purpose. For example, like a boat motor.
In this case, not the carburetor itself is subject to alteration, but the idle speed control system located on the throttle handle.
Device and principle of operation
The carburetor of the Ural KMP-100U chainsaw is of a membrane type. It does not have a float chamber and a floating float with a needle that cuts off the fuel flow as the chamber fills like older carburetors. This gives the advantage that the Ural 2t Electron chainsaw engine can work in any position, even upside down. The float carburetor cannot work in an inverted position.
The system of the KMP-100U carburetor can be considered complex, because it must ensure the operation of the engine in three modes:
- Maximum RPM.
For each mode, special channels for the supply of fuel, air and the position of the dampers are involved.
The appearance of the new KMP-100U carburetor used on the Ural 2T Electron chainsaw
When starting a cold engine, the conditions for the formation of a working air-fuel mixture in the combustion chamber are very unfavorable for the following reasons:
- Low crankshaft speed with a manual jerk of the starter, weak compression of the fuel mixture in the combustion chamber;
- Some of the fuel is lost on the cylinder walls;
- Low temperature makes ignition difficult.
Therefore, to facilitate starting, the supply of a rich mixture is required. more gasoline, less air. The air supply flap from the air filter in the cold start mode is closed, and the gas supply is increased due to pumping (suction) with a primer.
After starting the engine, a vacuum is created in the combustion chamber during the piston stroke, so the fuel mixture from the carburetor begins to be sucked in there. air is required for oxygen supply and complete fuel burnout. Air damper opens.
When the throttle is pressed, the throttle valve opens fully, gasoline and air flow in full flow, the engine runs at full speed.
The flow of gasoline at this moment is regulated only by the calibrated orifice of the jet in the carburetor.
How to adjust the carburetor on a Ural chainsaw
Adjustment of the KMP-100U is simple and accessible to every user. The carburetor has two adjusting screws (analogs of the H and L screws on some modern imported chainsaws) for adjusting the average and maximum speed. They are accessible from the outside, no need to disassemble the case for adjustment.
Above you can see 2 screws with springs, these are the adjusting screws
Adjustment of the carburetor of the Ural chainsaw is carried out on a warm engine. Initial tuning should be carried out on a warm, but muffled engine.
- Both screws can be screwed in all the way, but without excessive force. Screws have sharp, fine points that can deform if overtightened.
- Then the first screw, which is closer to the cylinder, is unscrewed by 1 turn. The second screw is unscrewed by 0.5 turns.
- They start the chainsaw, give full speed. In case of a drop in revolutions, the screws can be unscrewed by another 1/3 or 1/4 turn, listening to the engine’s operation and finding the optimal mode.
It is impossible to know the exact number of revolutions. On each chainsaw this is individual, depending on the characteristics of the carburetor, the state of the piston system, the quality of the fuel, the temperature outside, etc.
To adjust, it is enough to remove the cover, there is no need to remove the carburetor itself from the chainsaw
What other carburetors were put on the Ural 2t Electron chainsaw
On the Ural 2t Electron chainsaw, carburetors from other two-stroke engines with the following engine parameters were often installed, and are being installed today:
- Power 5.5 HP.
- Combustion chamber volume 90.4 cc,
- Piston diameter 55 mm.
Sometimes carburetors were installed from much more powerful engines. For example, from motorcycles “Minsk”, “Voskhod”. True, there is a drawback, the supply of the fuel-air mixture significantly increases. It was lowered by adjusting the screws. The engine was running, but the fuel consumption was significant.
Ural chainsaw carburetor repair kit
For KMP-100U carburetors, repair kits are still sold. a set of gaskets, a membrane, in other configurations there may be a rocker arm with a spring to it.
In the days of the USSR, when not only chainsaws were in short supply, but also spare parts for them, the gaskets were made themselves, from sheet paronite.
In the absence of paronite, the gaskets were made of thick single-layer paper (not cardboard) coated with oil paint.
Idle speed adjustment
The idle speed of the carburetor on the Ural chainsaw is regulated by a screw located on the gas handle. Its rotation changes the position of the throttle valve (opens it slightly) and, as a result, the idling parameters change.
This shows the maintenance of the KMP-100U, and at the end. a simple and understandable adjustment algorithm.
Ural chainsaw carburetor: device, adjustment, repair, revision
All Ural chainsaws were equipped with standard KMP-100 carburetors and its modifications with minor changes. And it was the only carburetor for chainsaws produced in the USSR. Later, with the advent of the newest and last in the USSR model Ural 2t Electron, the KMP-100U carburetor began to be used. And he was the only one for chainsaws produced in the USSR, which stood on Druzhba petrol chain saws.
Repair: basic faults and their elimination
Most often, problems with the fuel supply arise when the tiny openings of the nozzles are clogged and when the membrane-rocker pair fails. The brass cross of the rocker arm can bend, or jump out of the landing site and cut off the fuel supply at the wrong time. The soft membrane can dry out over time, lose elasticity, warp and also incorrectly shut off the fuel supply.
This is what the new membrane looks like (right)
There are two ways to clean the jet hole:
- The carburetor is purged with compressed air from a compressor or pump. The gasoline supply hose is removed from the tank, an air hose is put on the fitting and the carburetor is pumped.
- If the problem is not resolved, they remove it, disassemble it, gain access to the jets, clean and flush the entire chainsaw carburetor. The jet is cleaned in place or unscrewed (it is threaded).
The soft membrane on old carburetors most often fails after long interruptions in operation. It just dries up without gasoline. Therefore, before starting after a long downtime (a year or six months in summer in the heat), you need to open the gas tank tap, fill the carburetor of the Ural chainsaw with gasoline, and do a test run after half an hour.
An unusable membrane cannot be repaired, it is simply replaced.
Walbro carburetor for the Ural chainsaw
On the Ural 2t Electron chainsaw, the German carburetor from the Stihl MS 660 chainsaw, which is close in power, has proven itself well. Its fuel mixture supply almost completely corresponds to the Ural 2t Electron engine. Perfect fit is achieved by adjusting the screws. Also, the fitting dimensions are almost identical (between the holes on the carburetor and the studs on the engine). The difference of 1 mm is eliminated by sharpening both holes with a file, each by 0.5 mm.
It looks like a Walbro carburetor, which is put on a Ural chainsaw
Gasoline does not flow into the chainsaw carburetor
If the fuel does not enter the standard chamber, then this may indicate several breakdowns at once. The first step is to check the air and fuel filters. During long-term operation of the saw, these elements absorb a large amount of dust, which further prevents the infiltration of clean air and fuel. A slightly dirty filter can be cleaned with gasoline, but if the part is clogged with a lot of dust, then it will need to be replaced.
Another reason for the malfunction is the needle. This part sticks, especially in Chinese-made chainsaws. To fix the problem, in most cases it will be enough just to move the needle.
If no fuel enters the chamber, the saw owner should inspect the tool seals. After several months of using the tool, these parts lose their tightness. Over time, they begin to leak gas, as a result of which the instrument stops starting. Repair is carried out by replacing oil seals.
The breather plays an important role when starting the saw. It is located near the saw’s gas tank cover, and performs 2 tasks at once. it maintains optimal air pressure and does not allow fuel to flow out. To check the breather, you will need to turn off the fuel pipe and see how much gasoline flows out. If it does not leak at all, then the standard breather is clogged with debris and dirt. In this case, you will need to clean the element and reinstall it.
If fuel does not enter the chamber, then you need to check the fuel line. Most often, a Chinese hose is used to complete a budget-class tool, which eventually loses its tightness. In this case, it will be necessary to replace the line, paying special attention to the tightness of the channel joints.
Chainsaw carburetor device
Most modern chainsaws are equipped with nearly the same carburetors. They practically do not differ from each other, and work on a similar principle. The only difference between cameras from different manufacturers is the material from which they are made. In expensive American, Swedish and German chainsaws, cameras are made of reliable alloys, on which protective coatings are applied. Cheap Chinese and Korean chainsaws are equipped with nodes made from cheap materials.
Each carburetor consists of the following elements:
- Aluminum body with one-piece construction. Inside the body there is an inlet fitting, a main screw, an impulse channel, a bolt for adjusting the engine when idling;
- Throttle valve. it is responsible for adjusting the amount of air required to enrich the fuel mixture;
- Diffuser. located next to the camera inlet;
- Sprayer. designed to supply the fuel mixture directly to the carburetor chamber;
- Float chamber. there is a float in it, which is triggered in the event of an insufficient amount of fuel;
- Jets. are valves that are responsible for adjusting the amount of fuel.
This chain saw carburetor circuit is as simple and effective as possible. In some models of gardening tools, it can be supplemented with additional pipes, oil seals or filters.
The principle of operation of a chainsaw carburetor is quite simple. When the engine starts, the air damper located at the bottom of the housing opens. In this case, a vacuum is formed in the float and air chambers, caused by the movement of the piston. As a result, the standard diffuser is triggered, which begins to suck in air. The amount of intake air depends on the opening of the damper. When the piston is triggered, fuel begins to flow into the chamber through the inlet fitting. Its quantity and flow rate depend on the position of the nozzles.
Subsequently, the fuel in the air chamber begins to mix with air. After that, the finished air-fuel mixture passes through the intake valves, from where it is sent to the combustion chamber of the saw engine.
How to flush the carburetor of a chainsaw?
To clean the assembly from stubborn dirt, it is best to use a product that is available commercially in pressurized cylinders. The kit includes a dispenser and a long thin tube that allows you to spray the product in any hard-to-reach places.
It must be remembered that cleaning the carburetor on a chainsaw is carried out using flammable chemicals. You need to work with them in a special protective mask and only in well-ventilated areas.
To clean the carburetor on a chainsaw, the unit will need to be partially disassembled. The throttle valve, adjusting screws, housing and other carburetor parts will need to be rinsed with a bottle cleaner and set aside until completely dry. Once all the elements are dry, the unit can be assembled and installed back on the chainsaw.
Chainsaw carburetor adjustment. what a beginner needs to know?
Initially, all adjusting bolts are in the factory positions. this ensures that the optimal amount of fuel and air is sucked in. However, due to prolonged use of the saw in difficult conditions, the factory settings of its carburetor may be violated. Even a slight movement of one of the bolts by 1/5 of a turn will seriously damage the saw motor. In this regard, the operator must constantly monitor that the adjusting bolts are in the optimal, factory-set, positions.
If for some reason the work of the node has been disrupted, then it will need to be reconfigured. For this, 3 adjusting bolts are provided in the assembly device. The first of them is marked with the letter H. it is needed to tune the engine of the chainsaw when operating at maximum speed. The second screw marked L is used to adjust the motor when running at low rpm. The third screw can be labeled T, S or LA. Its task is to configure the internal combustion engine when operating in idle mode.
Chainsaw carburetor tuning must be carried out with a completely serviceable engine. Immediately before adjustment, you will need to inspect the air filter, and, if necessary, clean or replace it.
How to properly adjust the carburetor on a chainsaw?
Place the tool on a firm, level surface to set up the assembly. It is best to adjust the carburetor of the chainsaw in a place protected from dust and moisture.
The node setup process should look like this:
- First you need to unscrew the fastening bolts and remove the protective saw body. This will make it possible to inspect the carburetor and, if necessary, clean it;
- Next, you need to remove the standard air filter of the tool. If the saw is equipped with an additional foam insert, then it must also be removed;
- After that, you need a screwdriver, which you need to tighten the bolts marked H and L clockwise until they stop. This must be done very carefully so as not to break the bolts;
- Then both screws should be unscrewed 1.5 turns in the opposite direction;
- Next, you need to start the chainsaw engine and let it run for about 7 minutes;
- As soon as the engine cylinder heats up, you will need to start turning bolt L until the internal combustion engine starts working at maximum speed. Immediately thereafter, the bolt must be turned 1/4 turn in the opposite direction;
- Then you need to adjust the operation of the motor at high speeds. To do this, you need to connect an electronic tachometer to the engine, and start turning the bolt H until the readings on the instrument panel coincide with the instructions for the recommended maximum speed in the instructions for the saw;
- In the end, it remains to set up the operation of the internal combustion engine of the saw at idle. To do this, slowly turn the bolt T against the clock hand until the motor runs stably and without dips. If the engine starts to stall, then the T bolt should be turned in the direction of the clock hand.
To adjust the carburetor on a chainsaw, you should work as accurately as possible with the adjusting bolts. Excessive tightening of the screws will lead to increased stress on the engine and other important parts of the garden tool.
The carburetor of the chainsaw is the element that is responsible for mixing the air-fuel mixture. Not only the stability of the engine, but also the speed of the entire chainsaw depends on the condition and serviceability of this important unit. In this regard, each owner of a garden tool should study the design of the carburetor, as well as familiarize himself with the rules for its maintenance and repair.
Why the chainsaw shoots the carburetor?
If, during the launch and operation of the instrument, its owner hears sounds resembling shots, then this indicates a malfunction of the unit in which the fuel is mixed. The reason for this is most likely due to such malfunctions of the chainsaw carburetor:
- Pulled ignition. in this case, the fuel does not burn out, which leads to specific sharp shots;
- Carburetor supply with a mixture with a low concentration of gasoline. to correct the problem, you will need to adjust the jets.
If the shooting sound comes from the muffler, the problem is that the fuel mixture is oversaturated with gasoline. If there is too little air in the fuel, then it will burn not only in the chamber, but also in the muffler. This will be evidenced by a large amount of carbon deposits on the inner walls of the muffler.
How to properly adjust the carburetor on a chainsaw?
Before setting up the carburetor on a chainsaw, you need to carefully prepare for the procedure. First of all, it is necessary to find in the operating manual the descriptions of the angles of rotation of the adjusting screws. If you turn the bolts at random, without adhering to the manufacturer’s instructions, this can lead to serious damage to the engine’s internal combustion engine.
The motor itself must be in perfect working order. The air filter must also be thoroughly cleaned before tuning. Otherwise, it will not be able to pass air in the volume required to enrich the fuel mixture, which will lead to an incorrect carburetor setting.
Assembly adjustment should be carried out on a level surface. The saw itself must be installed so that the saw head is positioned away from the operator’s feet and face. Immediately before tuning, you will need to remove the upper part of the protective plastic case of the instrument, as well as remove the foam rubber and part of the standard air filter. A thin curly screwdriver is required to complete the node setup.
You need to adjust the carburetor of the chainsaw in 2 stages. The first one is basic. During its execution on the switched off chainsaw with a cold engine, it is necessary to screw in bolts H and L alternately in the direction of the clock hand until it stops. After that, each of the screws will need to be unscrewed 1.5 turns in the opposite direction.
The final carburetor adjustment is carried out in the following order:
- First, you need to start the chainsaw and give it time to completely warm up the engine. In this case, the throttle lever must remain in the medium speed position;
- Further, the screw, which is responsible for idling the engine, will need to be slowly turned in the direction of the clock hand. This must be done until the internal combustion engine of the saw starts to work stably;
- If, during stable operation of the motor, the chain moves along the tire, then the same bolt must be slightly unscrewed in the direction against the clock hand;
- Then you need to connect a hand tachometer to the motor. With its help, you need to find high and low work of the internal combustion engine. To do this, the adjusting bolts H and L must be turned alternately in different directions until the device shows the indicators that are indicated in the operating instructions.
At the end, the chainsaw used will need to be turned off and started again. It should work stably at idle, and its circuit should not rotate along the bus in this mode. When the throttle trigger is pulled, the saw should quickly gain momentum, and when released, it should drop.
Chainsaw carburetor adjustment
This procedure is necessary specifically in cases where the household garden tool does not start or, after starting, immediately stalls. Chainsaw carburetor adjustment is also needed when its power has dropped or the amount of fuel consumed has increased significantly.
For self-adjustment, each manufacturer includes adjusting screws in the complete set of their garden equipment. The bolt, marked with the letter H, is used to adjust the position of the main jet and the operation of the internal combustion engine at high speeds. Bolt L is required for basic adjustment of the position of the built-in motor-generated idle speed. Accordingly, the T screw is required by the owner of the chainsaw to quickly adjust the idling of the factory engine. In some cases, this bolt is also marked with the letters S or LA.
Chainsaw carburetor device
Almost all carburetors used in the production of chainsaws have one and the same device. The only difference is the mechanisms with which Chinese garden tools are equipped.
As standard, the fuel assembly consists of the following parts:
- Float chamber. this element is designed to continuously maintain the required amount of fuel. When the unit is in operation, the fuel is transferred through the built-in jet to the sprayer;
- Tube. through it the fuel flows in portions into the chamber. The fuel supply is regulated by the position of the built-in factory shutter;
- Sprayer. this part is required to inject fuel into the intake air stream.
The principle of operation of a chainsaw carburetor is quite simple. During operation of the unit, air is sucked in by the tube and passes through it at a speed that is regulated by a built-in damper. With the opening of the damper, the float located in the chamber is actuated. After passing through the diffuser, the air mixes with the fuel and is instantly atomized. The air-rich, high-quality fuel mixture then passes through the intake duct and into the engine cylinder. The diagram will clearly show the operation of the carburetor.
The fuel in the unit circulates under the influence of pressure. In the float chamber, it is close to atmospheric, and in a standard suction tube, the air is more rarefied. Due to the difference in the generated pressure indicators, the fuel mixture enters the pipe. The larger the amount of fuel, the higher the speed the engine of a household chainsaw can create.
The device and adjustment of the chainsaw carburetor
The carburetor is one of the most important parts of any modern chainsaw. Its main task is to mix the fuel mixture with air, as well as to further supply the finished fuel to the cylinder of the gas engine. During the operation of the chainsaw, its carburetor is constantly running, therefore, over time, this unit begins to need adjustment and flushing. Performing these procedures is quite simple, if you are extremely careful and follow the correct procedure.
How to flush the carburetor of a chainsaw?
You can clean the carburetor on a chainsaw using any aerosol cleaner. The best brands are Mannol, Hi-Gear and Nowax. These compounds well clean the walls and parts of the carburetor from accumulated dust, carbon deposits and hardened resin.
Both the Chinese and the German carburetor are washed in the same sequence.
Cleaning the carburetor on a chainsaw is performed in this order:
- First, you need to drain the used fuel remaining in the fuel tank. Next, you need to unscrew the mount and remove the protective cover of the chainsaw body, and also remove the standard air filter;
- Next, you need to remove the hose that is responsible for the fuel supply. To do this, you need to open the latches. After that, you need to unscrew the fasteners and remove the top cover of the factory assembly;
- Next, you need to dismantle the cover with a blue gasket, which plays the role of a membrane of the fuel pump. Spring-shaped brackets are located next to the body. They will need to be removed, as well as unscrewed;
- Then you need to unscrew the screw and carefully remove the needle valve. Directly below it is a built-in spring, which must also be removed. After that, you need to pull out the flap and the standard axle, gently pulling them along towards you;
- After that, you will need to remove the drive lever, as well as the throttle flap and its factory axis;
- All the removed parts of the chainsaw carburetor will need to be laid out on paper and checked for integrity. If necessary, worn out parts must be replaced;
- Further, all dismantled parts must be rinsed with a spray can. Do the same with the float chamber and carburetor body.
- After complete drying, all parts must be installed in the reverse order.
After flushing, the carburetor will need to be installed in its original place in the chainsaw. Further, the garden tool will need to start and observe its operation at idle and maximum speed.
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 the filter 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 reason for 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 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 valve, since it, most often, cannot be restored.
Why the chainsaw shoots the carburetor?
Often, chainsaw carburetor malfunctions are associated with loud extraneous sounds that come from the side of the unit. Ignoring them will lead to even more serious damage, which will be much more difficult to eliminate.
First of all, you need to understand the causes of extraneous sounds. The first of them is an incorrectly set ignition, due to which the used fuel does not have time to burn in the internal combustion engine cylinder in time. This leads to the formation of a short-term shooting noise that repeats with each cycle of fuel supply to the cylinder.
To eliminate the malfunction, you need to adjust the gap between the flywheel and the standard ignition coil of the chainsaw. To do this, remove the left protective cover of the plastic housing and clean the parts underneath. To the right of the ignition coil there are 2 screws, turning them counterclockwise will move the flywheel away from the standard coil. Next, you will need to attach a template to the side of the coil and start slowly turning the factory screws in the opposite direction. As soon as the built-in handwheel comes close to the previously installed template, you will need to stop turning the screws.
After adjusting the ignition gap, you need to check the operation of the chainsaw. If she still fires, then you need to examine the candle. If carbon deposits have accumulated on it, then the part must be cleaned and completely dried.
Another reason why the used chainsaw fires is the wrong proportion of the prepared fuel mixture. If it contains too little gasoline or engine oil, the garden tool engine will not be able to run smoothly. In this case, you will need to completely drain the fuel and prepare the mixture in accordance with the manufacturer’s instructions.
In some cases, a disruption in the supply of fuel to the engine cylinder may be caused by improper operation of the standard carburetor jets. In this case, you will need to adjust the carburetor and alternately check the operation of the tool at idle, low and high speeds.
How to extend the life of the carburetor?
To prevent damage to a standard unit, the owner of a garden tool should adhere to a number of rules. These include:
- Using a properly prepared fuel mixture. every time you mix gasoline and engine oil, you must strictly adhere to the proportions indicated in the operating instructions;
- Application for filling gasoline of the brand specified by the manufacturer. for the operation of an engine running on gasoline of the AI-92 brand, AI-95 fuel will not work, and vice versa;
- Regular flushing. cleaning the unit from dust and dirt accumulated on the walls will facilitate its daily work;
- Setting up the assembly immediately after detecting a problem. there is no need to postpone carburetor adjustments, as this can lead to even more serious damage.
During the operation of the chainsaw, you need to ensure that dust, sawdust and small debris do not seep under its body. Otherwise, they will quickly clog the carburetor and block its operation.