Adjusting the carburetor of a Chinese chainsaw: all the nuances, repairs

What carburetors are used on Chinese chainsaws

The most optimal carburetor designs for chainsaws were developed by the world's leading manufacturers - German Stihl, Japanese Walbro and others. These top developments are hard to beat. Therefore, most Chinese manufacturers copy the best models.

Today there is a large offer of Chinese carburetors for chainsaws on sale.

Some are nameless, from an unknown manufacturer and do not even have markings. They are simply offered for a specific chainsaw model. For example, a carburetor for a Stihl MS 361 chainsaw.

Others have brand names of well-known brands.

Still others have their own catchy names - in Russian transcription King Kong, Technopark, Rezet and others.

Features of the Chinese chainsaw carburetor

Their design and parameters differ depending on the power and model of chainsaw they are intended for. All of them are almost identical to the original carburetors in design, but not always in quality. Today, all Chinese products cannot be considered 100% rubbish. In turn, according to their quality, they can be divided into three groups:

Poor quality. Unsuitable alloys are used which oxidize, crumble and break. There is no accuracy of fit, the calibrated holes do not correspond to the required values, which leads to excessive consumption or lack of fuel in the combustion chamber. Critical parts quickly fail. Plastic parts quickly become rough or, conversely, become softened by gasoline and stop working. The axles and wire rods are bent, the threads of the fasteners are torn off. Such products are the cheapest. They are made in semi-handicraft industries using adapted equipment. As a rule, they do not have a name or marking.
Carburetors are of average quality. These are factory assembled products. They do not skimp on alloys; they have established continuous production with quality control. These are fully functional carburetors that can have a service life even longer than that of the entire chainsaw.
High quality carburetors. First of all, these are products from global manufacturers whose facilities are located in China. Geographically, they can be considered Chinese, but they are made using the technologies of the company that owns the brand and values its reputation. For example, Japanese Walbro carburetors are produced in China.

In addition, among Chinese manufacturers there are those who rely on high quality. They invest heavily in powerful production facilities, register their own brand and work on its reputation.

Adjustment algorithm

All work on setting up a carburetor chainsaw is carried out in four stages:

The engine is adjusted to ensure smooth operation at low speeds.
The carburetor is adjusted to create and supply a high-quality fuel mixture.
Fine adjustments are made at idle and only after the power plant has warmed up.
The quality of the tool is checked in all modes.

And now in as much detail as possible about how to adjust a chainsaw. If the tool does not start, then it is necessary to set the adjusting screws H and L to their original position. Then you have to start the engine and let it warm up. After this, you can begin adjusting at low speeds. To achieve optimal operating mode, screws L and T must be used.

First of all, use screw L to start the engine at maximum speed, and then release it by ¼. Screw T will allow you to adjust the operation of the power plant at idle. Adjustment of traction and maximum speed is carried out using screw H, which must be tightened slowly, while monitoring the readings of the electronic tachometer. It is important to remember that the maximum number of revolutions stated by the tool manufacturer must not be exceeded.

After making adjustments, allow the engine to cool. Then it remains to start it in accordance with the algorithm for starting a cold unit. If there are no problems at this time, and the chainsaw works well at idle, you should check it under load. If a lack of power from the power plant is detected, adjustment is made using screw H.

Almost all Chinese chainsaws are equipped with carburetors, the design of which is similar to European models. Therefore, the differences in setting will be insignificant - during the initial setting, screws H and L must be turned out two turns. All subsequent actions remain unchanged.

Most chainsaws of different brands presented on the Russian market today are made in China. Even well-known European manufacturers have production facilities using their own technologies, but in China. Chainsaws assembled in the EU and USA are found only in branded centers. Therefore, when we talk about carburetors on Chinese chainsaws, it is assumed that they are installed on most gasoline chain saws.

Adjusting the carburetor of a Chinese chainsaw with your own hands

Adjustment is not provided on all carburetors of Chinese chainsaws. Today there are many models of household chainsaws, including European brands, whose carburetors simply do not have adjusting screws. Or there is only one idle speed adjustment screw.

Such carburetors require adjustment only when the chainsaw at idle makes too few emissions (revolutions) and sometimes stalls. Below in the text we will discuss the algorithm for adjusting the idle speed of the carburetor on a Chinese chainsaw.

Required Tools

Adjustment requires a screwdriver that fits the slots of the adjustment screws. On different carburetors they are flat, cross-shaped, with an internal or external hexagon, an asterisk, etc.

An electronic tachometer will help with adjustment. If it is not there, adjustment is carried out by ear and by assessing the actual operation of the engine.

Carburetor adjustment algorithm

Before making adjustments, make sure it is necessary. All Chinese carburetors on each chainsaw undergo factory settings, which rarely go wrong. A new carburetor, or in rare cases an old one, may require adjustment.

The cause of deterioration in engine performance with symptoms similar to poor supply of the fuel mixture is, in most cases, the following:

clogged air filter,
exhaust windows and muffler clogged with carbon deposits,
bad fuel.

If this is not the problem, then try adjusting the carburetor.

The engine must be warm. A cold engine and one warmed up to operating temperatures operate differently. Therefore, adjustment in cold conditions will be incorrect.

Provide access to the adjusting screws. On some chainsaws, it is enough to remove the cover and air cleaner. On others you have to remove part of the body. On the third, the housing has holes for a screwdriver.
The screws are marked on the carburetor or near the holes - T (or LA) L and H. The T (or LA) screw is designed to adjust the idle speed. Always located away from screws L and H, which are next to each other.
If the chainsaw stalls when gas is supplied, the engine does not have enough fuel to develop speed. The amount of fuel is adjusted using screw H (main screw). Unscrew it 1/4 turn and give gas. If the engine begins to work better, unscrew it another 1/4 turn. (If worse, then tighten it 1/4 turn in the opposite direction).
If the engine starts to idle, it means there is a lot of fuel, screw H is screwed back.
The peak speed is controlled by ear or using a tachometer. The maximum speed for each chainsaw is indicated in the instructions. (10,000 – 12,500 rpm). In practice, 10,000 – 11,000 rpm in the “full throttle” position are normal values.
By increasing the amount of fuel supplied with screw H, the quality of the fuel mixture is adjusted with screw L. It increases and decreases the amount of air in the mixture. If there is not enough air, the fuel will not burn out; as a result, the engine smokes, does not develop power and consumes excess fuel. Screw L also affects engine operation at low and medium speeds.
After adjusting screw H, screw L is unscrewed 1/4 turn. If there is smoke in the exhaust and the engine moves from low to medium and high speeds with dips, screw L is unscrewed some more.
Adjustment of screw L is stopped when the engine runs smoothly, moves smoothly from low to high speeds and does not smoke.

After adjusting the two main screws, it is most often necessary to adjust the idle speed with the third screw.

The location of the adjusting screws is highlighted with a red square. To access them, a screwdriver is enough. There is no need to disassemble anything.

Idle speed adjustment

Idle speed adjustment sequence:

The engine is started and warmed up for 5-7 minutes.
The screw is unscrewed, increasing the speed until the chain begins to rotate.
Then the screw is screwed back 1/4 turn.

If you have an electronic tachometer, you need to use its readings when making adjustments. Most chainsaws should idle at 2500 rpm.

Nuances that arise in the process

Screw L should not be unscrewed too much relative to screw H. This will lead to the formation of a lean air-fuel mixture (not enough gasoline - too much air). With such a mixture, the piston is dry during operation, gets very hot and can fail.

The factory Chinese carburetor, which comes with the chainsaw, is configured on the benches taking into account the characteristics of each chainsaw. Therefore, any change in the position of the screws during adjustment must be remembered or recorded in order to be able to return to the factory settings if the engine does not start.

New carburetors on Chinese chainsaws, sold separately, are adjusted at the factories to a standard number of revolutions or arbitrarily. Therefore, they may require adjustment after installation on the chainsaw.

Adjustment video

The author of the video shows the process of adjusting a classic Chinese chainsaw with a power of 2.8 kW and a working volume of 45 cubic meters. see. The author talks in detail about all the stages of setup, what screws are there, what they are responsible for and how to adjust them correctly. The whole process takes place without removing the carburetor itself from the chainsaw.

The principle of operation of the carburetor

Regardless of the manufacturer of the chainsaw, the order and principles of operation of the carburetor remain unchanged. This device consists of several main elements:

Tapered air supply tube.
Fuel supply system.
Adjustable air damper.

Under atmospheric pressure, air, after undergoing preliminary cleaning, enters the narrow part of the tube, where its flow is regulated by a damper. Also here the air becomes rarefied and the resulting vacuum draws flammable liquid from the fuel line. To adjust the fuel flow, a special needle is used, connected to the nozzle chamber. The quality of the fuel mixture is regulated using a damper - when the air is opened, more fuel begins to flow into the carburetor and the power of the power plant increases.

To avoid problems with the operation of the tool, it is necessary to periodically adjust the chainsaw. When too much air enters the mixture, it becomes lean and engine power is reduced. Air deficiency also negatively affects the operation of the unit, as fuel consumption increases. At the same time, it does not burn completely, which leads to the appearance of carbon deposits on the cylinder walls. It is quite obvious that the question of how to adjust the carburetor on a chainsaw is asked by many owners of this tool.

However, first it is worth noting the signs of high-quality
operation of the power plant:

The momentum is picking up quickly.
The sound when the engine is running is similar to a four-stroke.
At idle speed the chain does not spin.

Chinese chainsaw carburetor repair

Carburetors cost 500-1000 rubles. It doesn't always make sense to repair. A repair kit with a set of gaskets and a diaphragm costs not much less than the cheapest carburetor, 300-350 rubles. A frequent breakdown of Chinese carburetors is the failure of the injector valve, and such a part is not sold in repair kits. Therefore, it is easier to buy a new carburetor.

But there are breakdowns that can be relatively easily fixed on your own:

Loss of seal between parts of the carburetor body or between the carburetor and the engine. Sometimes it is enough to tighten the fastening screws. In other cases, you can remove the carburetor, replace the gaskets, or use a suitable sealant along with them.

Obvious mechanical problems - deformation of the wire rod from the throttle, sticking of the axes on which the throttle and air dampers rotate - are also easy to fix. The thrusts are straightened. The axle landing sites are lubricated with a drop of oil and free rotation is developed by hand.

Carburetor cleaning

The carburetor air filter needs to be cleaned periodically. They come in different types. From some it is enough to knock out dust and dirt by knocking on wood. Others are washed with soapy water. Still others require disassembly. The fourth ones are almost impossible to clean; they need to be replaced with a new one.

The features of the air filter for each chainsaw and maintenance rules are described in the instruction manual for each specific model.

If there is a filter in the gas tank, nothing can become clogged in the carburetor. If there is still a suspicion that the tiny holes in the jet are clogged, the carburetor is disassembled. The parts are laid out on a clean cloth, remembering which one comes from where. The holes are purged with a pump or compressor. The body and parts are washed in kerosene or gasoline.

There is no need to bring the condition of the filters to such a deplorable state. This greatly affects the performance and life of the chainsaw engine.

Gasoline does not flow into the carburetor: what to do

The fuel line from the gas tank is short and uncomplicated. Three problems may arise in this area:

The gasoline supply hose is pinched. The break is found, the hose is straightened or replaced if the round shape is not restored.
The filter at the bottom of the gas tank, which is installed on some models of chainsaws, is clogged. It is removed with a thin wire hook, inspected and cleaned. The gas tank is flushed with gasoline.
The breather has failed. When fuel is sucked in, a vacuum is created in the gas tank, and fuel flows poorly or does not flow at all. This part cannot be repaired. Most often, the breather is located in a hard-to-reach place, at the outlet of the fuel line from the gas tank. It is replaced with a new one.

Sometimes, instead of repairing the breather, a hole with a diameter of 0.2-0.5 mm is made in the gas tank cap. The downside is that gasoline may leak through the hole during operation, and after operation the chainsaw can only be placed on its side, with the gas tank cap facing up.

How are things going with repair kits?

The repair kit can be purchased at the same retail outlets where carburetors are sold. They are sold in two configurations:

rubber-plastic parts (gaskets, diaphragm)
the same thing, plus a cross with a needle valve.

It is difficult to find other spare parts separately.

When customization is required

Modern “three-screw” carburetors of Carver chainsaws are practically not designed for manual adjustment at home. The screws are designed for factory settings, are securely secured against rotation during vibration by stable springs and do not change their position arbitrarily.

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But the carburetor screws of the Carver chainsaw are accessible for adjustment through special holes, without removing the casing, using a regular screwdriver. This suggests that such models structurally require periodic adjustment of the carburetor.

The reason for this cannot be stated from a technical point of view. Only versions available:

The Carver Carver chainsaw is in an area of strong vibration, so the screws unscrew spontaneously.
There is a rough spring installed which cannot secure the screw like other models.
Periodic adjustment is necessary due to the technical characteristics of the carburetor and the internal combustion engine of the Carver chainsaw as a whole.

Pros and cons of Chinese carburetors

Chinese carburetors can be of low, medium and high quality. Low quality products have the advantage of extremely low prices. The best option in terms of price-quality ratio is, as a rule, in the middle price segment.

An original European-assembled Stihl carburetor or a purely Japanese Walbro carburetor are excellent in quality. But their cost is sometimes equal to the price of an entire Chinese chainsaw. Therefore, it is better to confidently navigate the wide variety of Chinese carburetors with which our market is flooded, and make an appropriate choice.