How to tune the carburetor of a chainsaw: step-by-step instructions and tips from the masters
Performance and quality of work of a chainsaw depends on many factors, and one of the most important is the correct tuning of the carburetor. Technologically, this process is not complicated, but requires knowledge and consideration of some nuances. Improper adjustment of the chainsaw carburetor with your own hands can lead to malfunctions in the work of the tool and even to its complete failure.
Structure and principle of operation of the carburetor
The main purpose of the carburetor in an internal combustion engine is to mix fuel with air in certain proportions. When they are violated, the engine begins to work incorrectly or stops completely.
The carburetors of different brands of chainsaws have some differences in design, but the main components of this part and the principle of functioning are approximately the same:
- The base (body) is an aerodynamic tube with a transversely located air damper. Its purpose is to regulate the air flow inside.
- The swimmer chamber is the container that keeps the fuel mixture stable.
- The atomizer is the area where air and fuel come into contact. Fuel flows from the swim chamber through the nozzle into the atomizer.
- Diffuser is a part that increases the speed of air flow, by which the desired pressure is maintained. The diffuser is located in the narrowed part of the tube.
The principle of operation of the carburetor is as follows:
- After starting the engine, the choke opens and air flows into the duct.
- The flow rate and level of the swimmer in the chamber is regulated by the position of the flap due to the pressure difference in the swimmer chamber and the air channel.
- Fuel from the swimmer chamber is sucked into the bundle and then into the diffuser. The air passing through it captures the incoming fuel.
- The resulting mixture enters the cylinder cavities through the intake channels.
First setup and startup of the saw
Most tools are sold by manufacturers with presetting.
During commissioning, proper operation is checked:
- When first starting up, ensure that the chainsaw is running sparingly. A few hours after start-up, it is recommended to cut small branches and trunks up to 10 cm in thickness.
- The chainsaw must start up correctly, have a stable chainwheel speed and a smooth pick-up and drop-in performance.
- Fuel consumption should be consistent with the service used, and in practice the saw should not throttle, “sneeze”, smoke and work jerkily.
- There should be no strange thumps, crackles or noises when the engine is running.
The following rules will help you with protection:
- Mix gasoline and oil according to the parts specified by the manufacturer.
- Do not pre-mix. The properties of gasoline and oil when mixed change over time. The exception is fuel for intensively used tools, but even here you should not exceed the 7-day limit.
- Use oil designed for your chainsaw for a brand name engine. A fuel mixture with an abnormal composition will deactivate it.
- Consider the effects of climatic conditions on the components when preparing a fuel mixture.
Signs of improper carburetor operation
False carburetor operation can be due to a blockage in the intake port and improper adjustment.
Signs of false operation:
- Gasoline consumption is elevated, and there is thick white smoke coming from the exhaust;
- The engine runs hard, with a characteristic sound;
- The engine starts and adjusts or does not start at all.
- The chainsaw “shoots” at the carburetor.
Is an adaptation always necessary?
Before tampering with the factory carburetor settings, make sure that the improper operation of the chainsaw is related to them:
First of all, make sure there is a fuel mixture in the tank that is not ready to start the saw and goes into the carburetor.
When the tank is full, check the gas line. Disconnect the tube from the carburetor and swap them out. If all is well, the gasoline is spraying according to the manufacturer’s instructions.
A weak performance indicates a clogged conduit or fuel filter. In this case, cleaning the fuel tube and replacing the filter is sufficient.
Incorrect operation of the tool may be due to an overfilled gasoline saw tank. In this case you can see the bottom heads under the crater cover. In this case, check the fuel tube connection to the carburetor. Sometimes it pokes out when you unscrew the tank cap. The engine may not start for this reason.
The quality of the oil and gasoline mixture may be the cause of the bad belt. If you don’t drain the leftovers and store the tool for more than 2 weeks, the tank will develop processes of compounding and polymerization of the components. This can lead to fouling of the piston, rings and cylinder liner. Therefore, always prepare the mixture in the required quantity before working.
If there is nothing wrong with the quality of the fuel, the chainsaw engine may not start if the fuel and air filter becomes clogged:
To diagnose the fuel filter, separate the gasoline supply line from the carburetor and pump the fuel. The filter should separate when there is little or no pressure in the tube.
Remove the mixture tank and remove the filter element itself. A clogged cartridge can be cleaned, but it is best to replace it with a new one. Cleaning should be done regularly if the tool is operated in a dusty environment.
Carefully remove the air filter so that dust accumulated during operation does not get into the carburetor: this could require costly repairs.
After separating the cartridge, thoroughly clean off any accumulated dirt and rinse with detergent. Then dry and install it carefully.
The basic tool for turning the screws is a screwdriver that fits the slots. On different carburetors, they come in flat, cross and interchangeable with inner or outer hex, star.
Some tool manufacturers Husqvarna, Homelite and MTD complete their carburetors with jets for a special screwdriver. This is done to make it as difficult as possible for the owner to adjust the carburetor.
We can assume that the purpose of selling tuning screwdrivers is “culinary”: they are very expensive. However, this is done in order to improperly protect the saw’s engine from maximum revolutions.
Control of the tachometer settings. If this is not available, you have to navigate by your own hearing, and this is not always effective.
Step by step statement
The main stages of carburetor tuning:
- Tuning at low rpm;
- Adjustment for proper fuel delivery at maximum rpm;
- Fine tuning at idle speed;
- Checking the tool in all modes.
There are 3 screws used for tuning:
- T – responsible for fine adjustment at idle speed;
- H – responsible for tuning at maximum rpm;
- L – adjustment of fuel mixture formation at low revolutions.
Adaptation consists of the following steps:
- Set the L and H screws to the default setting. This is 1/5 turn of the screws until fully torqued.
- Point the engine and warm it up a bit.
- Set the low pregnancy mode with the L screw and idle t. First turn the L screw until the engine reaches maximum RPM. Then release 1/4 and bring it up to normal speed with screw t.
- After adjusting the operation to “floor”, adjust the thrust and maximum revolutions. To do this, turn the screw h slowly and check the RPM according to the electronic revometer information. Do not exceed the maximum revolutions recommended by the manufacturer.
- Stop adjusting the screw L when the engine runs smoothly, goes smoothly to low revolutions and does not smoke.
- The last step is to check the work of the saw in all modes. First let the tool cool down and then set the control to idle.
- If the tool works well, check it under load.
- Re-adjust the screw if it is not performing well, reposition it and check the traction again. Loss of traction at maximum rpm is an indication of a worn cylinder head or poor fuel quality.
A few tweaks
When adjusting the carburetor, some abnormal and performance hazards may arise:
- Tightening the L screw too much relative to the stored fuel-air mixture can cause it to form. If the carburetor has a lot of air and not enough gasoline, the piston group dries out and can fail.
- The Chinese carburetor factory has stock settings tailored to the properties of each chainsaw. Any change in screw position during tuning should be memorized or written down. This will help return to the factory settings if the engine won’t start.
- The new carburetor for Chinese saws is factory adjusted for the standard number of revolutions or randomly. It may be necessary to adjust for a particular tool immediately after installation.
Attitude. There are many Chinese models on the market now, less often European-made models that simply don’t have adjustment screws. Your configuration only comes with a screw in the mackerel tuning if the tool puts or specifies rare speeds).
How to know if the tuning is correct
Effective and correct tuning is based on the following signs:
Tune the carburetor of a chainsaw. Device, instructions, reviews
The quality and performance of your chainsaw assembly depends on many factors, but today we’re going to talk about carburetor failures. A lot depends on the performance of this assembly, including your good mood. You picked up your chainsaw and it won’t start, or it starts up and starts sneezing and firing, with a complete loss of power. Your day is ruined, and in your head thoughts – what is the reason, where to look for a wizard and how much will it cost to repair.
However, do not despair in advance, most of the faults of the carburetor can be eliminated with your own hands or adjusted in a nearby garage.
The main malfunctions
If you’ve ever taken an interest in carburetor construction, you couldn’t help but notice that all of the holes on the assembly are extremely small. Even minor contamination caused by bad fuel can cause improper fuel or air circulation. Yes, there are filters in the intake and exhaust ports, but they don’t always do their job. Where does this lead to? Any mechanic will tell you the consequences.
The main malfunctions of the chainsaw because of the carburetor:
- The consumption of gasoline has increased, there is a thick black smoke coming out of the exhaust pipe, a lot of carbon monoxide and soot.
- Engine starts, sneezes and shoots carburetor;
- The engine has lost power, chainsaws no longer “pull”;
- You were unable to start the chainsaw;
- It is impossible to achieve normal engine operation: RPMs are constantly floating;
- Chainsaws get up immediately after starting or when the throttle pedal is pressed sharply on the trigger;
As you can see, problems from a faulty carburetor are guaranteed to us. Moreover, without eliminating them, it is unlikely to be possible to disassemble the node and its subsequent adjustment. Therefore, it makes sense to get acquainted with the structure of the carburetor.
The construction of the carburetor
In this short review, we can not describe in detail all the details of the carburetor and thoroughly familiarize with all the nuances of its work, and we will dwell only on the main points.
The carburetor consists of such components:
- air impact tube. A small aerodynamic tube, which regulates the air flow. A transverse damper reduces or increases the enrichment of air, lean or fuel mixture.
- diffuser. Made in the form of a constriction at the end of the wind tunnel. The main task is to increase the pressure and velocity of the air when mixing with fuel.
- nozzle or atomizer. Designed for fuel delivery and mixing with oxygen.
- priming chamber. A special reservoir that provides a stable gasoline level at the air inlet.
Principle of carburetor operation
Most often, problems in the operation of the carburetor can be eliminated with their own hands. But to do this, you need to understand the basic principles of its operation.
The principle of operation of the carburetor:
- After starting the engine, the flap opens, through which the air enters the carburetor.
- In the air space, aerodynamic tubes and the float chamber, a zone of reduced pressure is created, while the air is absorbed by the diffuser.
- The intensity of the air flow varies depending on the position in which the flap is located;
- At this point, the gasoline from the chainsaw tank enters the diffuser, where it mixes with the air;
- A so-called fuel-air mixture is formed, which is sent directly to the combustion chamber through the intake ports.
carburetor adjustment period
Before taking a wrench and screwdriver in your hands, let’s understand in what cases the service station can improve the adjustment of the carburetor.
Adjustment of the carburetor is required when:
- Worn or damaged mounting screws. The reason for this can be a factory defect, as well as the vibration that accompanies the work of the chainsaw. If this malfunction occurs, it is possible to adjust the carburetor without removing it from the chainsaw.
- The most common cause of carburetor malfunction is contamination. The blame for this lies with the owner of the unit. Apparently, the owner did not pay proper attention to cleaning and taking care of the air filter and looked through his fingers at the fuel quality. In this case, an adjustment can’t get rid of more. Now you need to completely disassemble the assembly, blow out all the passages, flush it, remove scale and descaling, and then reassemble and adjust.
- A new chainsaw does not need adjustment. However, over time there is serious wear and tear on all parts, including the engine. Your chainsaw does not work well at high RPM and under load. The factory settings are no longer helpful. In this case, you can adjust the carburetor according to other parameters. However, this is a temporary solution, one way or another you will have to repair the engine.
As we have already said, the manufacturer specifies quite specific settings, at which your chainsaw should work well. However, in the process of operation there is wear and tear of individual components and parts, the factory adjustments are violated.
Moving one of the adjusting screws not even a quarter turn can lead to quite unpleasant consequences.
If you find that the chainsaw works with failures, which often dampens the loss of power for no apparent reason: it is time to adjust the carburetor.
The process of adjusting a Chinese chainsaw is done by manipulating three screws: H (high), l (low) and T. The T screw, depending on where and by whom your chainsaw is made, may be laming or have or have laming. la
- High: adjusts the chainsaw’s high speed operation, and is responsible for the main sharpener.
- Low: is responsible for engine operation at low rpm, is responsible for operation of the idle speed nozzle.
- T (s, la): This screw sets the optimum idle speed level.
When adjusting the carburetor, determine where to pass the chainsaw from the table of adjustment screw angles. Adjustment can be done with a special screwdriver or a regular flathead screwdriver.
Step-by-step instructions for adjusting the carburetor:
- Set up the chainsaw in a well-lit room or in an open area.
- The next step depends on the model of chainsaw. On some models the adjustment can be made without removing the air filter guard. Other manufacturers cover the screws with the housing, which must be removed.
- The main adjustment step begins with manipulating the H and L screws. When you feel resistance, pull back half a turn;
- Try to start the engine. If it does not start, get the desired result and turn the t screw clockwise, not more than ¼ turn;
Thus, we have found the initial parameters to start the adjustment.
- After the engine starts, allow it to warm up for 8-11 minutes.
- Use the L screw to find the highest engine speed and turn the screw out ¼ turn from this point. If you have a tachometer it is better to do this operation with it.
- The idle speed screw (t) allows the chainsaw to idle normally;
- Check the engine check and trace it in different modes.
- If the breakdown could not be eliminated at home, it is necessary to turn to experienced mechanics, who have not only knowledge, but also experience.
The process of adjusting the most common carburetors installed on Chinese chainsaws is given above. The adjustment process for some brands of chainsaws may have minor differences.
If possible, expensive equipment should be repaired in special workshops.
Overview of the Chinese chainsaw: diagnostics, repair and adjustment of the carburetor
Overview of cleaning, flushing and adjusting the carburetor of a chainsaw
Alexander Trofimenko, 33, Chernigov region
“Guys, I have a 270 chainsaw. Been working with it for two years now, but since some time it started having problems with the trunks and glitches. For a long time I couldn’t figure out what was going on, and then I found out that the carburetor settings were off. I took it off, disassembled it, cleaned it, washed it, reassembled it, stored it and ran it manually. Then went to a neighbor, borrowed a tachometer from him, and it turned out to work at 1500 rpm. So a good ear, and a gauge is better in such matters. “
Alexei Ivanov, 47, Tver
“After the winter the chainsaw began to start badly, the engine runs unevenly. Changed the spark plug in the champion, poured fresh fuel – did not help one bit. Had been puzzling over why this was happening for a long time, then realized – the whole reason was the fuel supply. My carburetor was riddled with fuel. I had to blow it up and put in a new one. It took me three days and two tanks of gas to do it. It may be funny to you, but I have experience, and I put my chainsaw in – I can’t get enough. “
Sergey Akimov, 51, Primorsky Krai
“I’ll tell you my sad story. Why sad and here’s why you should not get into the factory adjustments if you do not understand anything. To cut a long story short, I bought a chainsaw, started it up, it works fine – everything is as it should be. I decided to cut down an oak tree with a diameter of 50-55 centimeters. And it seemed to me that the power is not enough. Well, it is not enough, it is necessary to add, so I went to screws. I twisted them, but the chainsaw worked worse and worse, and then it would not start at all. I wasted nerves, time, and then money. Then turned on the workshop and with their crooked hands no longer advise me to touch the screws. The protocol is not sung. “