Installing a Chinese chainsaw carburetor

An internal combustion engine works by burning a pre-prepared mixture of air, oil and gasoline. Adjusting the chainsaw carburetor is necessary to prepare the mixture in the required proportion. The operation of the carburetor determines whether the engine will work with the declared power or stall.

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The principle of operation of the carburetor

Regardless of the manufacturer, the principle and operating procedure of the carburetor of internal combustion engines is the same. For mixing air and fuel, the carburetor is a device that includes:

• air tube with constriction;
• fuel supply system;
• adjustable air damper.

Air under atmospheric pressure, having passed the air cleaner, is supplied to the narrowing zone, where its flow is regulated by a flat damper blocking the cross-section. After the narrowing, a vacuum occurs in the pipe. As a result, the vacuum sucks fuel from the fuel supply tube, the outlet of which is regulated by a fuel needle connected to the float chamber by a nozzle. The design of a chainsaw carburetor is, in principle, no different from other fuel mixers for internal combustion engines.

The principle of mixing is to regulate the air damper and float level, depending on the degree of vacuum. We open the air - more fuel comes in, the engine increases speed. The correct fuel mixture ratio depends on the precise adjustment of the chainsaw carburetor. If there is a lot of air in the fuel, power drops and the mixture is called lean. With a lack of air, there is a high fuel consumption, incomplete combustion, carbon deposits on the cylinder and the exhaust of unburned fuel. This indicates that the mixture is oversaturated.

According to the instructions, the Ural chainsaw requires running-in using an enriched fuel mixture. Therefore, the carburetor comes from the factory with the setting for the break-in period. When switching to operating mode, the node is configured again.

Signs of a good chainsaw carburetor:

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• the engine runs smoothly, resembling a four-stroke sound;
• fast acceleration;
• At idle the chain does not turn.

Chinese Chainsaw Carburetor Adjustment

Content

Do-it-yourself chainsaw carburetor adjustment

For an independent carburetor option, you need to familiarize yourself with its structure and understand the procedure for the work that is carried out to adjust the parts responsible for the proper functioning of the components of the device and parts close to it.

It is necessary to carefully handle items for the system option, and also to determine whether the set characteristics correspond to very acceptable values.

About the carburetor design

The carburetor serves to mix the flammable mixture with air while maintaining predetermined proportions. If clear doses are not followed, the proper operation of the engine is at risk. When a huge amount of air enters during mixing of the components, but there is not enough fuel, then such a mixture is considered “lean”.

Oversaturation should not be allowed, because with a larger amount of fuel compared to air, malfunctions or engine wear are also likely. Carburetor adjustment is needed not only before initial use, but also when any differences in its operation are detected. Before starting to work with a chainsaw, do not forget to run it in.

Carburetor components

The carburetor design contains a standard set of parts, but may vary slightly depending on the manufacturer. Components:

1. The basis . This is a special tube that is visually similar to an aerodynamic design. Air passes through it. In the transverse direction, a damper is located in the middle of the pipe. Its position can be changed. The more it is extended into the passage, the less air enters the engine.
2. Diffuser . This is the constricted part of the tube. With its help, the air supply speed increases precisely in the segment from which the fuel comes out.
3. Channels for fuel supply. The fuel mixture is contained in the float chamber, then passes into the nozzle, from which it flows into the atomizer.
4. Float chamber . It is a separate structural element, reminiscent of the shape of a tank. Designed to constantly maintain the optimal level of fuel fluid before entering the channel from which air enters.

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Or explore foreign chainsaw manufacturers such as Shtil.

What you need to have for setup

Each carburetor owner must have the necessary tools to adjust this system. There are three adjustment screws that are located on the body of the device. They have their own markings:

• L - screw for correcting low speeds.
• H - screw for adjusting high speed.
• T - regulates idle speed, in most cases used for experiments.

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Chainsaw air filter

Before adjusting the carburetor, you need to prepare the device:

1. The engine warms up, that is, it starts about 10 minutes before repairs, and turns off when starting work (see how to start a chainsaw).
2. The air filter is checked and washed.
3. The chain is stopped by turning screw T until it stops (see chain oil).

To carry out a safe repair, you need to prepare a flat surface where you can carefully place the device and turn the chain in the opposite direction. Need a tachometer. It determines whether there is a malfunction in the carburetor. When turning the screws, the sound should be perfect and absolutely smooth. If you notice squealing notes, the mixture is oversaturated.

Setup instructions

Carburetor adjustment is divided into two main stages. The first one is called basic. It is performed with the engine running. The second is performed when the engine is warm.

To carry out the carburetor setup procedure successfully, you need to read the operating instructions for a specific model in advance to identify additional features of setting up the device.

First stage

The adjusting screws for the highest and lowest speeds should be moved clockwise until the highest resistance is met. When the screws reach the stop, you need to move them in the opposite direction and leave them 1.5 turns.

Main stage

How to adjust the carburetor of chainsaw

The video discusses a simple but effective way to adjust the carburetor

using an inductive tachometer. Similar

Adjusting the carburetor on a Chinese chainsaw (practice)

Spare parts for Chinese chainsaws

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How to adjust the carburetor
on .

The engine is turned on at medium speed and warms up for about 10 minutes. The screw responsible for adjusting the idle speed should move clockwise. It is released only when the engine reaches stable operation mode. It is necessary to ensure that the chain does not move during this process.

In idling mode, the engine may stall (the reason is here). In this case, you must immediately turn the adjusting screw clockwise until it stops. Sometimes the chain starts to move. In this case, turn the adjusting screw in the opposite direction.

Checking acceleration operation

Need to do a little research. Acceleration of the device is initiated. It is necessary to evaluate the proper operation of the engine during maximum speed. When the engine is functioning correctly, it means that when you press the accelerator, the speed quickly increases to 15,000 rpm.

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If this does not happen or the increase in speed is too slow, you must use the screw marked L. It turns counterclockwise. Moderate movements must be observed, since the turn cannot be more than 1/8 of a full circle.

Maximum number of revolutions

To limit this indicator, you need to use a screw marked H. To increase the number of revolutions, turn it clockwise, and to reduce them in the opposite direction. The maximum frequency should not exceed 15000 rpm.

If you make this figure larger, the device’s engine will wear out, which will lead to problems in the ignition system. When rotating this screw, you need to take into account the ignition processes of the device. If the slightest malfunctions appear, then the maximum speed value must be reduced.

Final check at idle

Before this procedure, it is necessary to carry out a full adjustment of the carburetor components when operating at maximum speed. Next, you should check the functioning of the device in idle cold mode. When the correct adjustment parameters are achieved, you will notice that the carburetor design closely matches the following criteria:

1. When the idle cold mode is activated, the chain does not move.

Chainsaw accelerator

1. When the accelerator is pressed even slightly, the engine accelerates at an accelerated pace. With gradual deepening of pressure, you can notice that the engine speed increases proportionately, reaching the maximum permissible values.
2. When the engine is running, you can compare its sound to a four-stroke device.

If violations are noticed in the given parameters or the device has not been fully 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.

Disassembling the carburetor if necessary to check or repair components

The design of different carburetor models is almost the same, so when working with them you can use the standard scheme. All elements must be removed carefully, and then laid out in the order given below , so that you can successfully place the items in place after the completion of the repair work.

Removing the Top Cover

1. The top cover is removed. To do this, you need to unscrew the 3 bolts holding it in a circle.
2. The foam rubber is also removed, since it is the upper component of the filter that conducts air.
3. The fuel hose is removed.
4. The drive thrust is output directly to it.
5. The cable end is disconnected.
6. The gasoline hose can be completely removed if you systematically pull it off the fitting.

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To finally prepare the carburetor for major repairs or replacement of the smallest parts, you need to carefully disconnect it from the main system . Sometimes further disassembly is required. You should unscrew the components carefully and put the fasteners in groups, as these small parts are easily lost.

Instructions for Chinese

To correctly configure the carburetor of a Chinese chainsaw, you must first remember the factory settings of the device, then turn on the engine. Subsequently, you will have to leave it running for several hours in order to accurately set your own parameters. Sometimes work is carried out only after ten minutes of engine operation, but many Chinese-made models require special handling.

Chinese chainsaw model

Adjustment procedure:

1. Activities begin in idle mode . Using the adjusting screws, you need to achieve a systematic increase in engine speed, so you should first let it run at low speeds. A deviation from the norm is the movement of the chain along the bus. In this case, you need to adjust the outer screws to the optimal position so that the chain remains motionless.
2. The transition to medium speed speed is carried out . Sometimes the engine starts to smoke. This defect can be eliminated by tightening the screw to supply a leaner fuel mixture.

In this case, the smoke will disappear, but the engine speed will increase. You need to adjust the settings until you reach a level where, when you press the throttle, the engine smoothly picks up speed, and no sudden jerks or interruptions are heard.

• The device's engine is being checked . The chainsaw is switched to minimum speed, and then the lever is quickly pressed. When pressed maximally, it is held for 3 seconds. If there are problems with the engine, you need to gradually loosen the screw until the optimal position is reached.
• The chainsaw should work for several hours in real conditions . You need to cut wood, and then inspect all the elements involved in this event. If there are deviations, they must be corrected using adjusting devices. When all defects have been eliminated and the optimal settings have been established to supply correctly concentrated fuel, the device setup process can be considered complete.

Take a look at the video:

Conclusion

In order for the chainsaw to work properly, you need to carefully carry out the work of adjusting the carburetor in exact accordance with their order. If any malfunctions occur in the operation of the device, you must completely disassemble it yourself. In most cases, replacement of any parts that have become unusable is required.

By constantly checking the quality of carburetor settings and taking timely actions to improve its operation, problems with the chainsaw will not arise.

Read about which chainsaw to choose here.

How to find a carburetor malfunction

However, adjustment may be preceded by repair of the carburetor itself when it cannot fulfill its function as a fuel mixer.

If fuel does not enter the engine for some reason, you need to check the condition of the fuel supply unit. Often the cause is the supply of low-quality gasoline, as a result of which the fuel passages become clogged.

If the fuel mixture has stood for a long time, the additives have broken down, and the mixture may clog the passages and grate with sediment. In this case, a long rinsing is required, which is done using solvents in a service workshop.

Purpose

In the USSR, 2 models of chainsaws were mass-produced - the Ural and Druzhba, and there was also the Parma electric saw. The Druzhba model was planned for small farms and was a “folk” product, and the Ural model was positioned as a professional-level tool intended for logging on an industrial scale.

Although in general these two saws are very similar, the Ural, as a more professional tool, has the ability to rotate the blade to a horizontal position in order to cut down a tree trunk while standing and not put so much strain on the operator’s back.

The use of the Urals in everyday life or at work greatly facilitates the already physically difficult work of loggers. This chainsaw can not only cut down trees, but also use it as an assistant in construction and household work, dismantling, bucking, and sawing firewood.

Do-it-yourself troubleshooting

If you do the troubleshooting yourself, you need to make room and arrange small parts. Tool required:

• brush;
• screwdriver for cross-threaded heads;
• socket wrench or M6 head;
• pure gasoline.

The main thing is to properly release the unit from the installation site, cleaning the outside of it from dirt. The air intake is removed, opening access to the carburetor and choke rod. Remove the accelerator lever by lowering the carburetor choke. Release the part by removing the choke lever, lifting the wire along with the lever towards you, hooking it on the left.

Rinse the freed carburetor in gasoline, blow it with air, clean the grille by injecting it with a thin needle.

When reassembling the assembly, make sure that the spring under the needle lever is in place. If you forget it, the fuel is not cut off, the spark plug is damp and does not produce a spark.

It happens that on a Shtil saw the gas key sticks slightly. In this case, it is necessary to clean the throttle from deposits. After cleaning, it is necessary to protect the damper with tinning.

After assembling the carburetor, installing it in place, make adjustments as described above.

What other carburetors were installed on the Ural 2t Electron chainsaw?

The Ural 2t Electron chainsaw was often equipped, and is installed today, with carburetors from other two-stroke engines with the following engine parameters:

• power 5.5 hp
• combustion chamber volume 90.4 cc,
• piston diameter 55 mm.

Sometimes carburetors from much more powerful engines were installed. For example, from motorcycles “Minsk”, “Voskhod”. True, there is a drawback: the supply of the fuel-air mixture increases significantly. It was reduced by adjusting the screws. The engine worked, but the excessive fuel consumption was significant.

Walbro carburetor for Ural chainsaw

On the Ural 2t Electron chainsaw, the German carburetor from the Stihl MS 660 chainsaw, which is similar in power, has proven itself well. Its fuel mixture supply almost completely corresponds to the Ural 2t Electron engine. A perfect fit is achieved by adjusting the screws. Also, the mounting dimensions are almost identical (between the holes on the carburetor and the studs on the engine). A difference of 1 mm is eliminated by sharpening both holes with a file, each by 0.5 mm.

This is what a Walbro carburetor looks like, which is installed on a Ural chainsaw

How to install a Chinese carburetor on a Ural chainsaw

The native ZiD plant in Perm no longer produces Ural 2t Electron chainsaws and spare parts for them. There are Chinese-made KMP-100U carburetors on sale that cost about 1,500 rubles. They are not always of good quality. And users prefer to install not them, but carburetors from Chinese mopeds.

These are high-quality products that have the following advantages:

• designed for long service life;
• economical;
• provide easy engine starting.

Progress does not stand still, so modern carburetors are far superior to the old KMP-100 in all respects. Carburetors from the following mopeds (scooters) are used:

• Alpha;
• Delta;
• Assets;
• Harley.

The carburetors of these mopeds are almost the same, and the engine characteristics are similar to the engine of the Ural 2T Electron chainsaw.

In this video you can see how the Ural 2t Electron chainsaw with a carburetor from a Chinese moped actually works:

The latest modification of the Ural chainsaw - 2t Electron with a KMP-100U carburetor began to be produced more than 30 years ago. It is gradually fading into history. But it seems that it will not go away soon, due to its high maintainability.

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:

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