Chainsaw carburetor Druzhba 4 - from design to adjustment and repair

What kind of carburetor is on the Druzhba-4 chainsaw?

All old-style Druzhba-4 chainsaws have KMP-100 carburetors.

KMP-100 is notable for the fact that it was the only carburetor for chainsaws in the country. It was also installed on the Ural chainsaw. And besides the Druzhba and Ural chainsaws, no others were produced or imported into the country. Therefore, we are familiar with the KMP-100 carburetor. It is simple, reliable, and designed with a large margin of safety.

On models of Druzhba-4 chainsaws produced after 1993, you can find carburetors KMP-100A and KMP-100AP. Today, such carburetors can be found on sale both in the “nameless” version and under the Rezer brand. Options A and AP differ significantly both from each other and from KMP-100 and 100U.

We are looking at the old classic KMP-100 carburetor, which worked on millions of Druzhba-4 chainsaws, many of which are still in use today.

The red square in the photo marks the location of the carburetor on the Druzhba-4 chainsaw

This is what the new KMP-100 carburetor looks like

Device

KMP-100 can be considered a new generation carburetor, despite its age. For the first time in the country, an elastic membrane was used instead of a float. Before that, chainsaws used float carburetors, like all two-stroke engines (mopeds, motorcycles, etc.). In a float carburetor, when the carburetor storage chamber is filled, the float floats up and its needle axis cuts off the fuel supply.

The float carburetor cannot operate upside down, which is a big disadvantage for chainsaws. But a diaphragm carburetor can operate in any position, even when the chainsaw is upside down.

The KMP-100 carburetor is made according to the classical design.

Main details:

• A housing with channels for the supply of fuel and air, a fuel storage chamber and a mixing chamber for the fuel-air mixture (Venturi tube).
• Case cover.
• Throttle (gas) valve.
• Jet with calibrated hole.
• Elastic membrane.
• A rocker arm with a valve that shuts off the fuel supply from the gas tank when the carburetor chamber is filled.
• Two adjustment screws.
• Gaskets.

In total, the Druzhba-4 chainsaw carburetor has 25 parts, including non-removable channels and chambers in the body.

For a better understanding, we suggest that you read an excerpt from the repair instructions

Principle of operation

The KMP-100 carburetor ensures operation of the internal combustion engine in three modes:

• Cold start.
• Low and medium speeds.
• Maximum speed (full throttle).

Before the engine starts, the fuel supply to the engine is shut off by a membrane connected to the valve.

Before starting, fuel is pumped up manually using the pump button (suction or primer).

• How to adjust the carburetor on a Ural 2 Electron chainsaw

When starting and operating the engine, the piston stroke creates a vacuum in the carburetor diffuser. Due to the pressure difference, the membrane bends, presses on the valve and opens the fuel supply.

The fuel is mixed with air and, due to the vacuum formed during the stroke of the piston, is sucked into the combustion chamber.

The adjusting screws determine the amount of fuel supplied and the quality of the fuel-air mixture. A fuel mixture that contains a lot of gasoline and not enough air is called enriched.

An overly rich mixture may not burn completely due to lack of oxygen. This leads to excessive fuel consumption or flooding of the spark plug.

A lean mixture contains little gasoline. The engine cannot operate at full power, the mixture is dry, the piston system overheats and wears out faster.

Engine speed is controlled by the position of the throttle valve in the carburetor. When it is fully open, the fuel-air mixture flows without restrictions (full gas).

Gas trigger that regulates the opening of the throttle

When it is closed, fuel flows to a minimum and the engine runs at idle speed.

What material is the Druzhba-4 chainsaw carburetor made of?

When assembling the KMP-100 carburetor, parts from different metals are used.

• The KMP-100 carburetor body is cast from an alloy of aluminum and zinc.
• The adjustment and fastening screws are made of steel.
• The jet with a calibrated hole is made of brass.
• The membrane is made of elastic, petrol-resistant plastic.
• The throttle body is made of a steel-based alloy, with additives for resistance to oxidation and corrosion.
• The gaskets are cut from paronite.

The body of more modern KPM 100U carburetors could be cast from an aluminum alloy with the addition of magnesium to lighten the weight.

How to adjust the carburetor on a Druzhba-4 chainsaw

Adjusting the carburetor of the Druzhba-4 chainsaw is required when the engine starts to work incorrectly - it stalls at idle, does not pick up speed when gas is applied, and “fails.”

• Do-it-yourself carburetor adjustment for VAZ 2107

To access the adjusting screws of the KMP-100 carburetor, you do not need to remove the housing cover; they are always open and accessible. There are no screw markings on the carburetor body, like on modern chainsaws. The first screw, which is located closer to the cylinder, regulates the fuel supply at low and medium speeds. The second screw is the main screw, it regulates the fuel supply at maximum speed

Required Tools

A screwdriver (minus) is required for operation. If desired, you can use an electronic tachometer. It will show the number of revolutions before and after adjustment.

General adjustment algorithm

The carburetor is adjusted in different ways. The simplest and most effective is ongoing adjustment during operation.

Lots of gasoline - spin

• The engine is warmed up for 5-10 minutes.
• If in the “full throttle” mode the engine operates as if idling (does not develop speed due to excess gasoline in the fuel-air mixture), the second (farthest from the cylinder) screw is tightened clockwise 1/4 turn.
• If the engine begins to work better, tighten it another 1/4 turn. If the engine starts to stall when the gas is fully applied, the screw is unscrewed back.

Low on gasoline - unscrew

• If the engine stalls in the “full throttle” mode (there is not enough gasoline in the fuel-air mixture), the adjustment begins by unscrewing the second screw by 1/4 turn and testing the operation of the engine. If it gets better, unscrew it some more until the engine begins to “choke” and run as if idling at full throttle. Then the screw is tightened back.

After adjusting the second screw, check how the engine operates in the transition from idle to medium and maximum speed. If there are dips, unscrew the first screw 1/4 turn and test changes in engine operation.

As a result, the optimal operating mode of the engine is found through such trial regulation.

Adjusting the idle speed on the Druzhba-4 chainsaw is done using a screw located on the gas handle. Its position determines how far the throttle valve in the carburetor is open at idle.

Idle speed is adjusted based on two requirements:

• Do-It-Yourself Chainsaw Carburetor Adjustment Caliber

1. The engine should not stall.
2. The chain should not spin.

Adjustment in a different sequence is possible. The screws are first tightened to the end, then unscrewed by 0.5 - 3 turns (different sources indicate different numbers of turns).

The video shows a simple and understandable process for adjusting the KMP-100 carburetor on the Druzhba-4 chainsaw from the screws position “tightened completely and then turned out”:

For beginners, we recommend watching a more detailed video about adjusting the KMP-100U carburetor of the Druzhba-4 chainsaw. The author of the video tells everything that is useful and everything you need to know. Just a whole step-by-step guide from A to Z.

Step-by-step algorithm

1. Unscrew the fastening screw.

2. Remove the fuel hose.

3. Unscrew the top damper cover.

4. We remove the carburetor.

5. Remove the membrane cover to adjust the level. You need to unscrew 6 screws in a circle.

6. Let's half the body and assess the condition of the membrane, it must be intact - this is the main thing, cracks, scuffs, and tears are not allowed.

7. We evaluate the performance of the mechanism responsible for the operation of the valve.

8. We blow through all the holes and clear out any debris if there is any.
9. We set the level by adjusting the height of the tongue; it should be on the same edge as the body.

10. If everything is done correctly, then by applying, for example, a ruler, you will see that the tongue and the edges of the body are on the same level.

11. We unscrew the screw with the needle from the central jet and assess its condition, clean everything from dirt, if there is any, blow it out in any case. The screw located above, also visible in the photo, is responsible for idle speed; it also needs to be unscrewed, the condition assessed and blown out with air.

12. This completes the cleaning, put everything back together in the reverse order and put the carburetor back on the chainsaw.
13. Don't forget to replace the air filter and pump up the fuel before starting.

14. Let's try to start the chainsaw.

Possible nuances and problems

In any case, when tightening the screws all the way, you need to remember the number of turns made for each screw. This will make it possible to return to the original adjustment if suddenly the chainsaw, adjusted according to the recommendations, does not start at all.

The problem is also that Druzhba-4 chainsaws of late production may have different carburetors, completely different in design from the KMP-100. For example, with one adjustment screw or no adjustment options at all.

Forester Income from waste

Chainsaw Druzhba-4 - do-it-yourself repair. Should I choose a chainsaw or an electric saw? How to choose the right chainsaw?

If you are the owner of a Druzhba-4 chainsaw, which sometimes malfunctions, then our article is just for you. We will tell you about more frequent dilemmas presented by the friendship chainsaw 4, the repair of which is possible even at home.

If you are the owner of a Druzhba-4 chainsaw and understand the techniques of working with a chainsaw, which sometimes acts up, then our article is just for you. We will tell you about more frequent dilemmas presented by the friendship chainsaw 4, the repair of which is possible even at home.

Contact ignition on Druzhba is very sensitive to different brands of gasoline and oils and causes a lot of trouble for many. Elements of such ignition are not repairable and are not cheap. We advise owners of old chainsaws to change contact ignition to electric ignition. This will free you from constant problems with its regulation and, as a result, save money. In addition, we recommend reading the article setting up the ignition of the Friendship 4 chainsaw.

If the spark plugs are wet #8212 means the carburetor is overfilling. We fix the problem by slightly bending the gasoline valve inward. This will limit the amount of fuel entering the combustion chamber.

We tighten the fuel screw until it stops and unscrew it three turns; we screw the air screw until it stops and unscrew it two turns. It may be useful to seal the connection between the carburetor and the cylinder to prevent air leaks - another probable reason for the saw to not work. You can use a special sealant or wrap the adapter coupling with a strip of narrow sheet metal. In general, all connections, including gasoline pipes and carburetor membranes, must be sealed; this is the key to high-quality operation of the chainsaw.

For more detailed information about the Friendship 4 saw, read the article Operating instructions for the Druzhba-4m Electron chainsaw.

Gallery

Carburetor. mounted on saws. consists of a housing, the inner part of which is made in the form of an air nozzle (Venturi nozzle). The air drawn in from the engine flows through this air nozzle. The smaller the cross section, the greater the air flow speed, the greater the vacuum. Fuel nozzles are connected to various places in the air nozzle (diffuser), from which fuel is sucked in by the air flow. It is necessary to be extremely careful when adjusting the chainsaw carburetor.

The fuel pump, injector system and adjustment devices for optimal preparation of the air-fuel mixture are integrated, or built-in, into the housing.

Fuel consumption, and therefore engine power, is controlled using the throttle valve.

The pulse cavity of the fuel pump is connected through a pulse channel; low or high pressure controls the pump diaphragm. Thus, the fuel pump operates depending on the engine speed.

For combustion of the air-fuel mixture, oxygen is required, which comes along with the incoming air. To prevent dust and dirt from getting into the drive mechanism and carburetor, an air filter is installed in front of the latter.

Fuel is supplied by the pump diaphragm from the fuel tank through the fuel line, the suction head, the carburetor intake pipe, the pump inlet and outlet valves and the fuel strainer to the inlet needle, and the inlet valve to the diaphragm control chamber.

The inlet needle of the chainsaw engine is connected to the control membrane through the inlet control lever. The cavity under the control membrane is connected to the atmosphere through a hole in the lid. Changes in pressure in the cylinder and crankcase also affect the operation of the carburetor. During intake, a vacuum occurs in the Venturi nozzle, and as a result, depending on the position of the throttle valve, an air flow occurs. In this case, fuel is sucked from the jets and mixed with the passing air.

The fuel is atomized in a diffuser (Venturi nozzle), resulting in the formation of the air-fuel mixture necessary for combustion in the cylinder.

The mixture is fed into the cylinder. Here, individual drops of the mixture evaporate due to high temperature.

The cavity under the control membrane is connected to the atmosphere, so the membrane is pressed upward. At the same time, the inlet needle is lifted from the seat by means of the inlet adjustment lever, and new fuel enters the membrane chamber. Thus, the control membrane is installed so that a constant amount of fuel is drawn in from the jets.

The amount of fuel flowing from the jets into the diffuser can be adjusted by the main adjustment screw and the working mixture adjustment screw when the friendship electron chainsaw is idling.

When the adjusting screws are unscrewed, the mixture becomes richer; when screwed in, the working mixture becomes leaner. The idle speed can be further adjusted by an idle fuel control thrust screw located outside the carburetor crankcase, acting on the throttle shaft lever.

Using adjusting screws, the optimum engine power can be constantly adjusted under different external operating conditions (for example, in the mountains or at sea level). Friendship chainsaw repair is best left to professionals. And don't forget to follow the instructions for Chainsaw Friendship.

Review from a chainsaw owner

I decided to create this topic on our favorite forum, since I couldn’t find anything like it on the Internet - everywhere everyone writes at random and there’s practically nothing about it. So. Before, during and after each use of your chainsaw, you carry out its normal maintenance, which includes such procedures as preparing and filling the fuel mixture and chain oil, adjusting the chain tension, regular cleaning (after each use) of the underframe (sprocket, chain brake, oil supply) and tires with chain, straightening a dull chain, cleaning the air filter and others. But sooner or later your chainsaw. Regardless of the manufacturer's brand, it undergoes some minor repairs. For more than 2 months now I have had an impossibly simple chainsaw from the Ryobi brand (ryobitools.ru) PCN 4040. French assembly and from the same Chinese (like all other saws, including high-profile brands like Shtil and Husqvarna), but Quite high quality parts. Later I found out that this is the twin sister of the HomeLite 4016 saw, only in a different color and with different branded stickers. In general, it doesn't matter.

During this short period of time, 3 malfunctions were identified and eliminated: 1. It became very difficult to start (it would start normally, everything was according to the instructions, but after working for 5 seconds it would stall. 2 times I had to carry out the procedure of completely starting a cold engine - then it would start normally). 2. Dips appeared (even stalling) when accelerating at minimum-medium speed. Initially, when I bought them, they were the same, but somehow softer. 3. At medium-high speeds, the saw began to shake in the hands and simultaneously emit wa-wa with a frequency of approximately 20-30 Hz. The first 2 malfunctions appeared almost simultaneously, and therefore plunged me into shock and confusion. I read a lot on the Internet about carburetors, ignition systems, I even found and downloaded the full details (.) of my saw! I'm afraid to take the saw apart - it's still under warranty. One day my patience ran out and I turned (tightened and unscrewed to the same position) screw L of the carburetor. Screws L and H have plastic end stops (you can't twist them too much - just half a turn each). Hurray, the malfunction of point 2 immediately disappeared! This means the carb was a little unfinished from birth. After that the saw began to accelerate beautifully. But point 1 did not disappear, and at the same time point 3 appeared. I climbed the entire Internet. I also read about tripping (of a single-cylinder engine, about detonation, etc. I replaced the gasoline - it was no use. I spat and removed the top crankcase cover. The air filter was very clogged (sawdust + dust + strengthened with oil). Washed it. Dried it. Started it up - nothing changed. . I unscrewed the spark plug (Champion was screwed in). And purely by accident I broke it (for fun I decided to unscrew the tip - I damaged the central electrode). The spark stopped appearing. I ran to the market to my grandfathers, as usual to motorists - there is no such spark plug! I asked purely by chance from the only one selling power tools there, he unexpectedly got me the same candle, only OREGON's in a package! Naturally, I called him handsome and well done, gave him 100 rubles for it. Came, screwed it in. Started it. Worked and won't stall! Didn't get it. I warmed up the engine a little and turned on the heat. There was a lot of happiness. After that, my girl buzzes smoothly and clearly, as before, does not shake, and at the same time, in addition, she also picks up speed beautifully (dynamically) when you press the trigger.

Read also: Clematis grandiflora Lech Kaczynski

Bottom line: The carburetor was a little unfinished at the factory. Only 1-2 degrees of full rotation. The blockage of the air filter worsened the situation - serious failures appeared in acceleration. This is my fault - the instructions say - regularly check the condition of the air filter! I almost forgot about him. The French decided to save money and introduced cheap Chinese counterfeits of candles from the famous Champion brand. You can see from the candle that this is bullshit. Hence, over time, poor starting appeared and the engine shook at medium speeds; the spark plug began to produce a spark unstably (or a bad spark, I don’t know). Everything has been decided. And further. The material of the air filter is nothing more than the material of commercially available napkins such as pressed cotton wool (sold in every hardware store - multi-colored, and made in almost any city, including our Kislovodsk). So, if you’re too lazy to wash it, you tear off the old one, cut out a new one and glued it on. So I suggest sharing your experience and tricks on repairing and maintaining modern chainsaws!

Repair instructions for the Druzhba-4 carburetor

The most common causes of failure of the KMP-100 carburetor:

1. Contamination of fuel and air channels, nozzle holes.
2. Loss of tightness.
3. Failure of the membrane - rupture, loss of elasticity, etc.

In the first case, the carburetor is disassembled. The parts are laid out on a clean cloth, remembering which one comes from where. The body and parts are washed in gasoline. The channels and holes of the jets are purged and washed.

The tightness is restored by disassembling the carburetor, changing the gaskets or using a gas-resistant sealant.

If the membrane fails, it is replaced with a new one.

Before repairing and adjusting the carburetor, you need to make sure that fuel is properly supplied to it from the gas tank.

The Druzhba-4 chainsaw has a tank located on the handles and has a faucet with a filter, which can become clogged. You need to remove the fuel hose from the carburetor fitting and make sure that gasoline flows fully.

This carburetor can no longer be repaired. better to replace with a new one

Why does it overflow

If there is too much fuel in the combustion chamber, the spark plug may be flooded, the spark will disappear and the engine will not start.

If the engine does start, the engine cannot develop speed because there is not enough oxygen to burn the fuel.

If the overflow is small and the engine is running, there will be excess fuel consumption.

Often overflow occurs due to the adjustment screws being unscrewed too much, especially the second one. The problem is solved by adjusting the carburetor of the Druzhba-4 chainsaw.

The second reason is the failure of the membrane and the valve associated with it. A broken membrane and valve do not regulate the flow of fuel, and it comes in excess.

A one-time overflow when starting a cold engine can be caused by excessive pumping of fuel by the enrichment button (choke or primer button).

Fixing fuel filter breakdowns

Due to its malfunction, the chainsaw may stall even at idle speed.
To check, carefully disconnect the fuel line from the carburetor. If you see that during pumping, fuel does not flow out of the hose and practically does not reach the carburetor, it means that the fuel filter is clogged with debris. Use a wire hook to clean the filter. And drain all the fuel through the tank filler head. After this, disconnect the filter from the hose, clean it with detergents, dry it thoroughly and put it back in place.

In order for the chainsaw to work without interruptions, replace all filters every three months.

What kind of carburetor can be installed on Druzhba instead of the original one?

KMP-100 is a carburetor of good, but outdated design. Today there is a large selection of different carburetors from all over the world. Druzhba-4 chainsaws are equipped with carburetors from other chainsaws, mopeds, and motorcycles. The main thing is that the carburetor is designed for an engine of approximately the same combustion chamber volume and fits the mountings. If the new carburetor does not quite fit the mounts, adapters are used.

The Druzhba-4 chainsaw with a KMP-100 carburetor is a unit that was used to fell and saw millions of cubic meters of wood during Soviet times. The quality of these chainsaws from the 60s to 80s was so high that many of them are still in working order.

Intended mainly for work in logging sites and sawing logs obtained in this way, the Druzhba chainsaw is also indispensable in private households for solving many everyday problems. Not expensive, very easy to operate and repair, successful in technical terms - the Druzhba chainsaw has been conscientiously and effectively serving for more than 50 years, first to citizens of the USSR, and now to Russians. The range of prices for their acquisition is currently wide. In new condition (mothballed), depending on the modification, their cost ranges from 8 thousand rubles. up to 15 thousand rubles, and used ones, depending on the actual condition - from 1 thousand rubles. up to 7 thousand rubles

The content of the article:

Model range of chainsaws Druzhba

The advantages of the Druzhba chainsaw, in addition to those mentioned above, are that it cuts smoothly and accurately, is highly productive and all the parts are in a durable case. Its disadvantages include significant weight - more than 12 kg with dimensions of 86.546x50 cm and a cable starter.

The main difference between modifications of the Friendship chainsaw is engine power:

• Friendship 2 has a power of 2 kilowatts, manual start and, unlike the 1st model, an element for chain braking.
• Druzhba 4, which received “gold” at the World Technology Exhibition in Brussels in 1958, has almost one kilowatt more power, sawing effortlessly, with shaft revolutions of more than five thousand, a half-meter log in one minute.
• Friendship 4M-electron, having a contactless electronic ignition system, uses the engine resource more efficiently, with almost the same power - 3 kW. The cylinder's chrome coating adds wear resistance, and rubber gaskets reduce overall vibration. In modification 4A, an oil pump is installed for forced lubrication of the chain.

Like any other technical device, the Druzhba 4 chainsaw requires constant carburetor adjustment, attention, regular care and preventive maintenance. At least once a year it is necessary to fine-tune the Druzhba 4 carburetor, including its adjustment.

Models and their descriptions

Druzhba chainsaws today have almost the same design as the first models. Some details have been modified

By paying attention to the name, you can see the numbers that indicate power. For example, if in front of you is a Friendship 2 chainsaw, this indicates that its power is 2 liters

With.

In the first models, the handles were fixed on the fan cover; later they began to be attached to the clamp connecting the motor and gearbox. Until the 80s Models marked 4 A were produced. They had a KMP-100 carburetor and a contact magneto. For the first time, these devices began to use automatic chain lubrication. Later, this device was discontinued, and instead they began to produce a unit with electronic ignition called “4A-Electron”.

In the 90s the old carburetor was replaced with a new one - KMP-100U. They started calling the saw “Druzhba-4M” and additionally equipped it with updated chains. Based on the chainsaw, the Ural saw was developed, which had more outstanding characteristics

One of the latest models, “Druzhba 5E,” has a similar design. If you are interested in the “Druzhba” chainsaws, then you should pay attention to the marking, to which the letter E or the word “Electron” may be added at the end. This indicates that the unit has an electronic ignition system

Adjusting the carburetor of a friendship chainsaw

The internal part of the carburetor body of the Druzhba chainsaw is designed as standard - in the form of a Venturi air nozzle, through which the air supplied by the chainsaw engine passes, and gasoline enters the diffuser through the corresponding holes and jets. The throttle valve regulates gasoline consumption, the operation of the fuel pump depends on the speed of the saw engine, and the air filter prevents dust and dirt from entering the carburetor.

The main causes of carburetor malfunctions:

• Insufficient gasoline supply.
• Excessive gasoline supply.
• Violation of proportions when mixing oxygen contained in the air “driven” through the Venturi nozzle and gasoline.

The corresponding fuel and air screws, responsible for the supply of gasoline and oxygen, are first turned “all the way” and then two or three turns back. When the engine is warmed up and running, by turning these screws back and forth, you can adjust them by ear or using a tachometer to their optimal position for stable operation of the carburetor, including the Druzhba 4 chainsaw at maximum engine speed. At the same time, at idle, the chain should not freely change its position on the tire, and the motor itself should operate calmly and smoothly without any “roars,” “sneezes,” or other similar sounds. In addition, you need to check the correctness and reliability of the connection between the carburetor and the cylinder.

Technical characteristics table

Below are the technical characteristics of the Druzhba chainsaw; three main versions of the chainsaw were taken for comparison.

Adjusting the ignition of a friendship chainsaw

With a properly adjusted ignition, the Druzhba chainsaw will operate on the very minimum amount of gasoline required by its engine. Ignition occurs as a result of synchronous operation of the magneto, spark plug and corresponding wire, with the ignition coil being correctly and securely fastened. To check the spark strength, place the spark plug on the cylinder body and start the starter. If the spark is weak, then such a spark plug must be replaced. And if constantly checking the spark plugs is not part of your plans, then it is recommended to replace the contact ignition of the Druzhba saw with an electronic one.

Important! Malfunctions in the operation of the Friendship chainsaw motor are usually caused by malfunctions in the ignition system, and contact ignition itself is extremely sensitive. If a gas-powered saw has a non-contact electronic ignition, then most often the fault is caused by a burnt-out thyristor in the magneto. Recommendation: replace it with an imported one.

Most common faults

1. The engine does not start. Check for a spark at the spark plug electrodes. Make sure there is no damage to the wire insulation, clean or replace the spark plug if necessary.
2. Make sure the fuel tank is tight; interruptions in engine operation are often caused by moisture and condensate getting into the fuel mixture.
3. Adjust the carburetor
4. The most common cause of overheating is a lack of lubrication. Correct the problem.
5. Check the serviceability of the muffler. Its design is quite simple; repairs are possible at home.
6. The reason may be a malfunction of the ignition module, as well as a violation of the gap between it and the magnetic circuit in the flywheel. Gap length – from 0.2 mm. up to 0.5 mm.. This value is set using a special gasket, which is located between the flywheel boss and the ignition module. The broken module is replaced. In addition, you can replace the spark plug.

Chainsaw repair Druzhba

All breakdowns of Friendship chainsaws can be divided into several main groups of faults:

• Something is wrong with the lubrication system.
• Some component of a 1-cylinder, two-stroke, carburetor engine, or even more than one, has failed.
• The ignition system does not work, not producing a spark or producing it with a force insufficient to ignite the fuel mixture.
• Failure of other parts of the chainsaw (saw blade, frame with handles or gas tank).

If you are not an electrical engineer or a person with experience in numerous successful repairs, then self-repairs must be carried out in accordance with the instructions.

For example, constant malfunctions of the engine, sporadic inability to start it, and so on, can be caused by the following reasons:

• Lack of gasoline in the gas tank. It is necessary to add fuel to the appropriate mark.
• The spark plug is flooded with gasoline, which prevents the formation of a spark of sufficient power. This candle must be dried and calcined on a gas stove or other burner. This also indicates that the carburetor is out of adjustment and there is an excess of gasoline. To eliminate this, it is necessary to close the corresponding output and operate the starter for some time.
• Poor contact between the spark plug and the corresponding wire due to the resulting gap of more than half a centimeter. The spark plug is cleaned of carbon deposits (the electrodes are cleaned with fine-grained sandpaper) and blown out from all sides.
• The air filter is clogged with dirt. To be cleaned or replaced.
• The fuel filter is clogged with all sorts of debris. Using a wire hook, you need to disconnect the filter from the hose, clean it and, after thoroughly drying, install it back.

Important! In order to ensure that the Druzhba gasoline-powered saw operates without interruption, all filters must be replaced at least 2-3 times a year and cleaned as needed, but at least once a month.

• The muffler is clogged with dirt. Its spark arrester becomes clogged, mainly due to poor quality or the wrong brand of oil, or if its content in the fuel mixture is high. To be cleaned and dried, including the fuel pipe.
• Carburetor membrane sticking. Full adjustment with disassembly and reassembly or replacement of the carburetor.
• Due to low speeds, any 2T oil can be used. But it is necessary to maintain a ratio of 15:1.
• If the gas-powered saw stops working when tilted away from you, then it is necessary to change the crankshaft seals, and possibly the entire central piston group.
• Manufacturing defects. Delivery to the collection point specified in the instructions is required if the warranty period has not expired.

Also, repairs must be made in the appropriate workshop if the tire “drives.” A correctly sharpened and seated chain is more important than the strength of the engine. As a preventive measure, it is recommended to lower the chain into a container filled with liquid lubricant in a warm state.

Friendship 4, although an unpretentious, reliable technique, still time passes, chainsaws exhaust their service life and sooner or later begin to require repairs. Most often on Druzhba problems arise with the operation of the carburetor and the ignition system. The article describes in detail the stages of troubleshooting with your own hands, as well as other less popular ones. but common ones.

Device

The main parts of the chainsaw are as follows:

• engine;
• sawing apparatus;
• frame with handles;
• gas tank

The engine is a single-cylinder two-stroke carburetor. Cooled by air flow created by a centrifugal fan. The engine and sawing apparatus are independent units, connected into 1 unit with flange fasteners and secured with a clamp.

When the fuel tap is opened, fuel enters the diaphragm carburetor, which ensures uninterrupted supply to the engine at any angle of inclination and strong vibration. The design of the chainsaw does not allow the engine to stop if the chain gets jammed in the barrel while cutting wood.

The handles are located high, which provides the following capabilities:

• do not bend over while working and get tired less;
• work in deep snow conditions;
• increase user safety.

Correct carburetor adjustment

Inside the Druzhba chainsaw carburetor body is an air nozzle, which is blown by the chainsaw engine, and the fuel itself enters through the corresponding holes and jets. The flow rate of the oil-gasoline mixture is regulated by the throttle valve, and the operating mode of the fuel pump depends on the speed of the chainsaw engine. To prevent dirt and small dust particles from entering the carburetor, an air filter is installed on it, which perfectly protects the engine from environmental pollution.

The fuel mixture is considered normal if the weight ratio of gasoline to air is 1:15. With such a mixture, the engine operates at a power 5 percent lower than the maximum possible, and fuel consumption is 4-5 percent higher than the minimum.

The Druzhba chainsaw engine reaches maximum power when it runs only on an enriched mixture, with a weight ratio in the range of 1:12-1:13. If it is necessary to achieve the most economical operating mode of the engine, then the mass of air per 1 kg of gasoline should be increased to 16-17 kg; such a mixture is called lean.

For those who don’t know what we’re talking about, we recommend reading an interesting review of the Friendship 4 chainsaw.

If the amount of air in the mixture is increased further, our mixture becomes even more depleted and eventually the saw stalls. On the contrary, if you increase the amount of gasoline, at a ratio of 1:6-1:12 the mixture will be enriched, the engine will work with strain, a large loss of power occurs, and such operation is extremely uneconomical. An enriched fuel mixture is used when running in a new engine or after repair is required.

Adjusting the carburetor of the Druzhba chainsaw should not be done on a cold engine; before starting the adjustment, you need to let the engine run a little, maybe at idle.

Carburetor adjustment algorithm

1. The screw that regulates the quality of the fuel mixture is tightened all the way, and then unscrewed half a turn.
2. Using the idle screw (hereinafter referred to as the XX screw), the moment of the smallest but stable rotation of the crankshaft is found, then the screw that regulates the quality of the mixture (it is lean at this moment) is unscrewed until interruptions in engine operation occur.
3. Smoothly tighten the XX screw (the mixture is enriched at this moment) until the internal combustion engine operates stable. Tighten the screw that regulates the quality of the mixture again, lowering the crankshaft speed and fix the new position of the XX screw, which is responsible for idle speed.

The above operations must be repeated as much as necessary to obtain a minimum but stable crankshaft speed of the Druzhba 4 chainsaw.

If the engine stalls when you quickly open the throttle, you need to tighten the mixture quality screw a little, thereby enriching the mixture. And if the engine of the Druzhba chainsaw stalls when the throttle is quickly opened, you need to turn this screw a quarter turn, that is, lean the fuel mixture.

With correct and timely carburetor adjustment, the Druzhba 4 chainsaw will operate at the maximum possible power, while gasoline consumption will be minimal.

Ignition system repair

Childhood chainsaw disease Friendship 4 - difficulty starting a hot engine when stopped in operation. The reason for this is a weak and outdated ignition system. To increase the power of the spark at the plug, it is necessary to repair the ignition. Such a repair will correct the situation even if there is no standard coil.

Step-by-step algorithm for repairing the ignition of petrol tools Druzhba 4

1. The high and low voltage windings are removed from the standard ignition coil.
2. Instead of a low-voltage winding, 250 turns are wound onto our coil with special wire (for transformers). You can use PEV2 wire, with a cross section of 0.8-1 mm. We must not forget about interlayer insulation - a new layer of special wires is laid with paper. The beginning of the entire winding is connected by soldering to a standard output to the magnetic core, the other end of the winding is connected with a special mounting wire to the breaker. Then the coil is wrapped with electrical tape or covered with another insulator. The section of the capacitor circuit fed to the coil and the breaker does not undergo changes.
3. Using two wires through a piece of insulating tube, the ends of the connections are made. To prevent short circuits, all the resulting wiring can be placed in one insulating tube.
4. An ignition coil of type B-115 with a removed side resistor is ideal as a transformer. This type of coil is used in ignition of old Soviet Muscovites. It is not recommended to use motorcycle ignitions; they are not powerful enough to provide the required spark. The reel can be fixed to the chainsaw frame using a mounting clamp in any suitable place.
5. The wires from the internal combustion engine are switched according to the following scheme: the first wire, which connects the breaker, capacitor and coil output together, is connected to terminal B-115 with the designation “VK”, the second wire, which comes from ground, connected to the magneto mounting screw, is connected with output B-115 without identification marks. To make the diagram easier to read, it is better to use different colored wires.
6. Finally, the ignition coil is connected to the engine spark plug igniter using a high-voltage wire.

This repair of the ignition system showed an excellent result, the childhood disease of the Druzhba 4 chainsaw disappeared, such a system will work for a very long time.

The only drawback is that the appearance of the chainsaw has changed due to the external coil on the body, and the dimensions have increased. But this is a forced alteration, but the ignition system works reliably and the saw starts at any temperature.

If some points remain unclear, we suggest watching a video on the topic of repairing the ignition of the Druzhba chainsaw.

Why is Friendship 4 not gaining momentum?

Starting the Friendship 4 chainsaw is the most technically complex process in which all systems of the chainsaw are involved. But if you manage to start the engine, but when you press the gas handle the saw does not gain momentum, there may be many reasons:

• Malfunctions in the engine: the service life has expired, the cylinder or piston rings are worn out, rusted or scored;
• Malfunctions in the ignition system: the spark plug or coil winding has failed - the spark is weak or does not form at all and cannot ignite the fuel mixture;
• Malfunctions in the carburetor: incorrect settings, unbalance of the carburetor cover mounting bolts;
• Depressurization of the fuel system, engine crankcase;
• There is a lot of carbon deposits in the muffler and exhaust gases are difficult to release.

Eliminating the causes of ignition system malfunctions

1. Unscrew the spark plug, dry it if it is filled with fuel, replace it with a new one if it has strong black carbon deposits.
2. Make sure that the coil is not pressed tightly against the magnets, there should be a distance of up to 0.2 mm and free movement. If this is not the case, secure the coil to the required distance.

If these manipulations do not help, you can independently check the entire spark plug block for spark supply through the power cable. If there is a spark, but you cannot understand the cause of the problem, it is better to take the chainsaw to a service center.

Eliminating the causes of malfunction of the carburetor unit

1. Correctly adjust the chain saw carburetor. Read above how to do this.
2. Remove the carburetor cover, check the presence of all parts and their movement inside the block, secure the cover in place by evenly tightening the fastening screws, checking that the carburetor cover fits snugly.

Eliminating the causes of exhaust system malfunction

Dismantle the muffler, mechanically remove carbon deposits from the walls; if necessary, you can use white spirit, VD-40 or other solvents.

In other cases of malfunction, we advise you not to carry out independent repairs and trust the professionals of the service center.

About safety precautions

Before starting to work with a chainsaw, it is necessary to carry out a number of measures aimed at the safe operation of the device:

• checking the tightness of the fuel system;
• checking the cylinder fastening;
• checking the carburetor is secure;
• checking the muffler is secured;
• checking the tightness of steel fasteners from the outside;
• lubrication of the driven tire sprocket by immersing it in oil for several minutes;
• lubricating the starter cable with lithol-24;
• cleaning the air filter mesh on the carburetor.

It should be remembered that when the interfin cylinder space is clogged, it causes a significant decrease in cooling, severe overheating and accelerated wear of the working surface. After 24 hours of operation, partial disassembly should be carried out, followed by careful removal of carbon deposits.

When working, you must remember to strictly and compulsorily adhere to the following safety rules:

• It is prohibited to carry out work with one hand;
• work clothes must be durable and include gloves, work shoes, as well as a protective helmet and a special shield;
• Before refueling, the gas tank cap must be opened extremely carefully, which is due to the possible presence of gasoline vapors;
• work must be carried out on completely cleared sites, with reliable and strong support;
• you need to make sure that the chainsaw does not touch foreign objects during operation.

Do not refuel with the engine running. The saw should be transported after the protective cover has been placed on the bar.

How to start a chainsaw without a starter

Many people on the Internet are interested in the question of how to start a chainsaw without a starter. Let’s not give hope to our readers; it’s impossible to start a chainsaw, any kind, this concerns not only Friendship 4.

The manufacturer does not provide the ability to start the internal combustion engine in any alternative way other than through the starter. If you dismantle it and instead force the spark plug to give a spark by applying an external rotational force, starting the engine at idle, such an engine will not work for a long time, the chainsaw will be left without a cooling system.

The standard starter of the Druzhba 4 chain saw has a cooling scroll, the impeller of which directs a flow of cold air to the cylinder.

Finalization of Friendship 4

Many Western chainsaw manufacturers produce tuning kits for their saws to increase power, and service centers have a separate price list with a list of possible modifications. Mainly found in petrol tool service centers in the USA and Germany.

It is also possible to modernize and replace components in order to improve the characteristics of saws from the Druzhba family.

Examples of what can be done:

• Install turbocharging to increase the rate of supply of the fuel mixture;
• Install a more modern carburetor;
• Increase the compression of the fuel mixture;
• Install an electric starter;
• Bore the internal combustion engine and install an enlarged piston;
• Install the decompression valve;
• Leave one piston ring to reduce cylinder running resistance.

In general, the chain saw in question is a paradise for the implementation of engineering ideas. Craftsmen all over Russia assemble various devices, from a boat motor to a bicycle, based on this gasoline saw. We recommend reading an interesting article about what you can make from a Friendship 4 chainsaw with your own hands.