DIY chainsaw repair

In detail: DIY chainsaw repair from a real master for the site my.housecope.com.

The chainsaw is a worthy replacement for hand saws and axes. Today, this tool is available in almost every household - it is indispensable for setting up a personal plot, construction and repair work. Intensive use and improper care of the tool can lead to premature failure. However, the owner of the chainsaw does not have to go to the workshop right away - many of the faults that can happen to her during operation are quite realistic to eliminate on their own.

6 Checking the carburetor and signs of need for adjustment
7 Calibration algorithm and safety precautions when troubleshooting the chainsaw carburetor
8 Other chainsaw malfunctions
9 DIY chainsaw repair, video

Correct diagnosis is essential for a successful repair. Therefore, in order to determine why the chainsaw failed and, most importantly, how to make it work again, you first need to know the features of its design.

It should be noted that it does not differ in particular complexity, since it includes:

engine (two-stroke gasoline);
functional part (saw bar and chain);
systems that ensure the joint operation of these two units (ignition, filtration, lubrication, etc.), that is, the tool as a whole.

In order to simplify the diagnosis of malfunctions, it is customary to distinguish them into two main categories:

engine malfunctions;
malfunctions of other parts of the chainsaw.

Most often, failures occur in the engine systems, however, the rest of the tool, due to intensive use or improper care, can fail at any time. How to determine exactly where the breakdown occurred? Simple logic will help us with this.

Video (click to play).

If the problem is in the engine, it will:

do not start;
deafen;
work unstable;
overheat;
smoke;
develop insufficient power.

As for all other malfunctions, as a rule, they manifest themselves with a normally operating motor.

If your chainsaw won't start, the first thing to do is to check for a mixture of fuel in the tank. By the way, it must be prepared in the proportions indicated by the engine manufacturer, otherwise the instrument will simply not start.

After verifying that the fuel mixture is correct and available, the ignition system should be checked. To do this, you need to inspect the spark plug.

Her condition can say a lot:

indicates that the fuel mixture does not enter the carburetor, which means that the problem is not in the ignition;

fuel-splattered candle

is the result of an overabundance of the fuel mixture, which lies either in a violation of the engine starting algorithm, or in an incorrect carburetor adjustment;

this is a signal about the presence of low-quality oil in the engine lubrication system, incorrect carburetor settings, or an incorrectly prepared fuel mixture.

If the spark plug is splashed with fuel, wipe it thoroughly after removing it. The fuel supply system should also be cleaned. To do this, it overlaps, after which the starter is turned on. A carbonized candle must be carefully cleaned with an awl and emery.

When checking the spark plugs, you should pay attention to the distance between the electrodes (the normal gap is 0.5-0.65 mm), as well as the condition of the gasket and the presence of a spark. A damaged or worn gasket will have to be replaced, and the spark can be checked by putting on the ignition cable, connecting the cylinder and plug nut, and starting the starter.

If the discharge does not occur, the plug must be replaced. In the event that a spark does not appear with a new candle, then the problem is in the connection to the high-voltage wire or in it itself.

If the fuel mixture does not flow into the cylinder, but the spark plug is working properly, this may mean that:

Clogged fuel filter.

To clean this unit, remove the fuel hose and check the jet. If it is weak, the filter must be removed through the filler hole of the fuel tank and cleaned or replaced if completely worn out.

As a preventive measure, it is recommended to replace the fuel filter at least once every 3 months.

This is nothing more than a hole in the fuel tank cap, which is cleaned out with an awl.

The fuel mixture is not supplied or is supplied insufficiently.

There may be several reasons for this:

the air filter is clogged (in this case, it must be removed, rinsed with water, dried and replaced);
the carburetor settings are out of order (which means this unit needs to be re-adjusted);
the integrity of the carburetor membrane is broken (must be replaced);
the channels of the carburetor are clogged (it must be disassembled and all parts and assemblies must be cleaned).

If at low speeds the engine of the chainsaw works normally, but at high speeds it starts to stall and smoke, the problem may be hidden in the muffler.

To check the quality of its work, you should do:

dismantling (with the obligatory closing of the outlet);
disassembly (if the muffler is collapsible);
cleaning from carbon deposits using special detergents or dry method;
drying (using a hair dryer);
reassembly and assembly.

Dry cleaning without respiratory protection is not recommended. The carcinogens present in the soot will be released into the surrounding atmosphere in the form of dust, the inhalation of which is extremely hazardous to health.

To prevent clogging of the muffler during the operation of the chainsaw, you should carefully monitor the composition of the fuel mixture and the quality of its components.

If the chainsaw engine does not start or cannot develop normal power, it is likely that sufficient pressure does not build up in the engine cylinder for combustion of the fuel mixture. The reason for this may be the wear of the elements of the cylinder-piston group - the piston, rings, bearings, etc. In order to assess the condition of this unit, it should be visually inspected, having previously removed the muffler.

For a more complete diagnosis, a compression gauge is placed in the spark plug hole of the two-stroke engine of the chainsaw. It measures the compression in the engine. Based on the results of the check, one can judge the state of the CPG, however, the exact facts can only be obtained with a complete disassembly of the unit.

If the piston is chipped or scratched, it will obviously need to be replaced. The same applies to deformed or broken piston rings - for normal engine operation, they must be completely intact and free of carbon deposits.

A properly working carburetor guarantees maximum efficiency of the chainsaw, that is, it is possible to develop full power with the most economical consumption of the fuel mixture. The adjustment of this unit is usually carried out by the manufacturer, but its design provides for the possibility of adjustment already during operation.

The fact that such a setting will have to be performed by the owner of the chainsaw is evidenced by:

Strong vibrations or damage to the protective cover.
CPG wear.
Carburetor clogged.
Inability to start the engine or its spontaneous stops after starting.
Increase in fuel consumption and emissions while decreasing engine power.

Chainsaw carburetor adjustment is carried out in strict accordance with the manufacturer's instructions using three special screws, which are responsible for the maximum ("M") and minimum ("L") revolutions, as well as the idle speed of the engine ("T"). In order to exclude unwanted interference by an inexperienced user with the carburetor operation, some manufacturers install only one idle screw.

Carburetor adjustment is carried out in two stages:

Basic (carried out with the engine off).
Finishing (carried out with a running, pre-warmed engine).

For basic adjustment, screw in screws H and L as far as the stop and back out 1.5 turns. Final adjustments require the engine to warm up for 5-10 minutes at low revs.

The final calibration is performed by unscrewing the idle screw until the minimum engine speed is reached (in this case, its operation must be stable, and the chain must be stationary). If the engine stops at idle speed, the screw must be returned back, and if the saw chain is still in motion, continue turning counterclockwise.

Calibration check is performed by test:

Acceleration (with a smooth press on the accelerator, the engine should quickly pick up speed to the maximum indicator).
Maximum speed (if there is an ignition interruption, screw H should be slightly loosened).
Work at idle speed (the chain should not move, and the engine should pick up speed as quickly as possible).

If the owner of the chainsaw is not familiar with the carburetor device and does not have the tool necessary to calibrate it, contact a specialist. The carburetor is a very complex unit, so any wrong action can lead to irreversible consequences, for example, complete engine failure.

If the diagnostics showed that everything is in order with the engine and its systems, then the cause of the malfunction should be looked for in other units of the chainsaw. The most common problems are:

failure of the starter;
improper operation of the lubrication system;
incorrect operation of the chain brake;
saw chain wear, etc.

If the cause of the tool failure is not visible to the naked eye, as is the case with the engine, it is necessary to perform a thorough diagnosis of the faults and eliminate them in accordance with the manufacturer's recommendations and safety regulations.

It should be noted that it does not differ in particular complexity, since it includes:

engine (two-stroke gasoline);
functional part (saw bar and chain);
systems that ensure the joint operation of these two units (ignition, filtration, lubrication, etc.), that is, the tool as a whole.

In order to simplify the diagnosis of malfunctions, it is customary to distinguish them into two main categories:

engine malfunctions;
malfunctions of other parts of the chainsaw.

If the problem is in the engine, it will:

do not start;
deafen;
work unstable;
overheat;
smoke;
develop insufficient power.

As for all other malfunctions, as a rule, they manifest themselves with a normally operating motor.

After verifying that the fuel mixture is correct and available, the ignition system should be checked. To do this, you need to inspect the spark plug.

Her condition can say a lot:

indicates that the fuel mixture does not enter the carburetor, which means that the problem is not in the ignition;

is the result of an overabundance of the fuel mixture, which lies either in a violation of the engine starting algorithm, or in an incorrect carburetor adjustment;

this is a signal about the presence of low-quality oil in the engine lubrication system, incorrect carburetor settings, or an incorrectly prepared fuel mixture.

If the fuel mixture does not flow into the cylinder, but the spark plug is working properly, this may mean that:

Clogged fuel filter.

To clean this unit, remove the fuel hose and check the jet. If it is weak, the filter must be removed through the filler hole of the fuel tank and cleaned or replaced if completely worn out.

As a preventive measure, it is recommended to replace the fuel filter at least once every 3 months.

This is nothing more than a hole in the fuel tank cap, which is cleaned out with an awl.

The fuel mixture is not supplied or is supplied insufficiently.

There may be several reasons for this:

the air filter is clogged (in this case, it must be removed, rinsed with water, dried and replaced);
the carburetor settings are out of order (which means this unit needs to be re-adjusted);
the integrity of the carburetor membrane is broken (must be replaced);
the channels of the carburetor are clogged (it must be disassembled and all parts and assemblies must be cleaned).

If at low speeds the engine of the chainsaw works normally, but at high speeds it starts to stall and smoke, the problem may be hidden in the muffler.

To check the quality of its work, you should do:

dismantling (with the obligatory closing of the outlet);
disassembly (if the muffler is collapsible);
cleaning from carbon deposits using special detergents or dry method;
drying (using a hair dryer);
reassembly and assembly.

To prevent clogging of the muffler during the operation of the chainsaw, you should carefully monitor the composition of the fuel mixture and the quality of its components.

For a more complete diagnosis, a compression gauge is placed in the spark plug hole of the two-stroke engine of the chainsaw. It measures the compression in the engine.Based on the results of the check, one can judge the state of the CPG, however, the exact facts can only be obtained with a complete disassembly of the unit.

The fact that such a setting will have to be performed by the owner of the chainsaw is evidenced by:

Strong vibrations or damage to the protective cover.
CPG wear.
Carburetor clogged.
Inability to start the engine or its spontaneous stops after starting.
Increase in fuel consumption and emissions while decreasing engine power.

Carburetor adjustment is carried out in two stages:

Basic (carried out with the engine off).
Finishing (carried out with a running, pre-warmed engine).

For basic adjustment, screw in screws H and L as far as the stop and back out 1.5 turns. Final adjustments require the engine to warm up for 5-10 minutes at low revs.

Calibration check is performed by test:

Acceleration (with a smooth press on the accelerator, the engine should quickly pick up speed to the maximum indicator).
Maximum speed (if there is an ignition interruption, screw H should be slightly loosened).
Work at idle speed (the chain should not move, and the engine should pick up speed as quickly as possible).

failure of the starter;
improper operation of the lubrication system;
incorrect operation of the chain brake;
saw chain wear, etc.

One of the most important parts of any chainsaw is the cylinder-piston group (CPG), which transmits the rotational motion to the drive sprocket. Despite the reliability of this unit, most models require diagnostics and repair over time.It is the performance of the chainsaw's CPG that determines the power of the unit, its ease of starting, the presence of idle speed and the consumption of the fuel mixture.

There are many reasons for the failure of the CPG, which are usually divided into two main categories: natural wear and tear and artificial malfunctions. The first type of malfunctions, as the name implies, is the physical wear of the rubbing parts of the piston group. The second category is more extensive and implies:

Elements of a piston chainsaw

strong overheating of the internal combustion engine and, as a result, the appearance of thermal seizures on the surface of the piston;
breakage of the lower part of the piston (skirt) due to the duration of the chainsaw operation at maximum speed;
ingress of foreign particles into the combustion chamber and the occurrence of mechanical damage to the CPG;
breakage of the compression (piston) ring due to severe wear or exceeding the permissible saw speed;
inconsistency of the recommended portions of gasoline and oil when preparing the fuel mixture.

Worn chainsaw piston

Experts do not recommend disassembling the CPG for no particular reason. However, if the tool has significantly lost power, there is a metallic ringing in the internal combustion engine, or the crankshaft does not turn when the starter jerks, the piston chainsaw should be diagnosed. First of all, to identify engine malfunctions, it is necessary to measure the compression in the cylinder. With a significant deviation from the values recommended by the manufacturer, we can safely say that there are scratches, wear and tear on the surface of the cylinder or piston. It is the drop in compression that is the basis for the complete disassembly and repair of the piston group of the chainsaw.

For the prompt diagnosis of the CPG for a breakdown of the chainsaw compression ring or scuffs in the cylinder, professionals advise to remove the muffler and assess their condition through the outlet window.

The dimensions of the cylinder-piston group are determined primarily by the diameter of the piston made of heat-resistant aluminum alloy. Regardless of the model, the CPG of the chainsaw consists of a cylinder, a piston, a retaining pin and two retainers.

Chainsaw cylinder mirror

When buying a piston chainsaw, you should pay attention to the inner surface of the cylinder, which must be polished and have a glossy shine. In the presence of damage, scratches, experts do not recommend installing such a cylinder.

In order to increase the compression in the working unit and, as a result, increase the power, many manufacturers install two piston rings each. The chainsaw compression rings made of special cast iron adhere tightly to the cylinder, as a result of which the tightness of the combustion chamber is ensured.

If the time has come to replace the CPG of the chainsaw, you need to know that for each specific model there is an individual algorithm of actions. To facilitate disassembly / assembly work, you must prepare a spark plug wrench, a large flat screwdriver, a hammer, a compressor for cleaning the unit parts, a set of open-end and socket wrenches. Regardless of the manufacturer and design features of the model, before removing the cylinder of the chainsaw, the following work must be performed:

Dismantling the upper protective cover;
Unscrewing the spark plug;
Removing the side cover;
Using a large flat screwdriver, the stoppers are removed from the shock absorbers;
In the channel of the candle we place a lace to fix the crankshaft and unscrew the clutch and flywheel nut;
Dismantling the drive chain sprocket;
We remove the carburetor with an air filter;
Remove the ignition module and exhaust system.

After removing it from the base of the power unit, unscrew the pallet and remove the crankshaft with the piston from the cylinder. Using plumbing tweezers or a screwdriver, dismantle the piston pin stoppers.

Before dismantling the piston, it is necessary to remember its location in the cylinder, so that later you do not waste time on re-disassembling and assembling the power unit.

Chainsaw pan sealantBefore starting the assembly, it is necessary to clean the parts and assemblies of the unit from dirt, sawdust residues, dust with compressed air, rags and other means. The first step in replacing a piston chainsaw is to install a piston on the crankshaft. We fix it on the connecting rod with a steel pin included in the delivery of the CPG. In order to prevent arbitrary falling out of the retaining rings, it is recommended to install them with a cut down. Next, we mount the compression rings on the piston, but due to their fragility and fragility, this operation must be approached as carefully as possible. To prevent the formation of scratches, before installing the piston in the cylinder, the piston must be lubricated with oil. Before installing the crankcase (pallet), you will need to degrease its mounting surface and apply a layer of heat-resistant sealant. We assemble the chainsaw in the reverse of the algorithm described above.Often, replacing the chainsaw piston, crankshaft and compression rings solves problems with idle and problematic starting of the internal combustion engine.

After washing, dry the non-separable muffler with a hairdryer. Remember that soot contains substances that are carcinogenic, and dry cleaning, after which they may be inhaled, is unacceptable. When removing the muffler, plug the engine outlet with a clean cloth.

The muffler can become clogged for the following reasons: due to the use of a fuel mixture with a large amount of oil (the oil level is recommended by the manufacturers), the use of low-quality oil or oil, which is not intended for two-stroke engines.

The most serious are damage to the cylinder-piston group of the chainsaw. This is the worn out piston and cylinder, scuffs and scratches on their surfaces, sinking in the piston ring grooves and their wear, as well as wear on the crankshaft bearings. In the usual way, these malfunctions provoke a drop in the level of pressure in the cylinder and the impossibility of starting the engine in the future, or its inability to deliver full power.

There are several ways that help assess the condition of the cylinder-piston group. Remove the muffler and look out the window where you can see part of the side of the unit. Despite the limited overview, a general understanding of the CPG can be obtained.
Turn the crankshaft using an electric motor with a flexible shaft or a starter by hand, while monitoring the pressure on the pressure gauge.

For a workable chainsaw, the last indicator should be in the range of 0.8-0.9 MPa. With its fall, the power of the engine also decreases. At a pressure level of 5 atm, the engine can and will work, but at idle speed.It will be possible to accurately assess the state of the CPG only after repairing the saw-free parterre with your own hands, which consists in disassembling the engine - disconnecting the crankcase from the cylinder and removing the piston. If the latter has seizures, deep scratches or chips, it must be replaced. If the cylinder surface is damaged or worn out, there is a chance to bore it to the repair size. Low compression is caused by coking and piston ring wear.Serviceable rings are always clean from carbon deposits, sit loosely in the piston groove and press tightly against its inner surface.Rare do-it-yourself Ural chainsaw repair manuals do without mentioning the breakdowns of the chain lubrication system, which are quite common. They usually manifest themselves as insufficient or non-supply of lubricant to the chain and in the formation of oil leaks. If the chain is dry, first of all, it is necessary to inspect the channels through which the oil is supplied to the tire and clean them. Their clogging is not uncommon. Image - DIY chainsaw repair

If there is a significant leakage of oil (a small level of leakage is considered normal), it is recommended to check the tightness of the connection to the pipe fittings of the pump. They can crack or fall off. In addition to smudges, a violation of the tightness of the oil line can also provoke insufficient lubrication of the chain. The pump will suck in air, which will definitely affect its performance. It is customary to eliminate such violations by sealing the tubes with a sealant or replacing them. The most serious malfunction of the lubrication system is cracks that form in the oil pump housing. It needs to be replaced in this case.

Some parts of the chainsaw, which are subject to natural wear and tear, must be replaced after a certain period of useful life. Their breakdown is a pattern and not at all a malfunction. The wear parts include a tire, a chain, a drive sprocket, anti-vibration system units and others.

If you do not repair your husqvarna chainsaw with your own hands and replace wearing parts in time, then their excessive wear will affect other parts of the chainsaw in the most negative way. In particular, if the drive sprocket and tire are not changed in time, then the increased vibration will badly affect the crankshaft bearings. The limit of the depth of development of the sprocket teeth should be up to 0.5 millimeters.

Although sprockets in practice often operate until wear of 1 millimeter or more, without suspecting that this causes an increase in the loads on the crankshaft bearings, accelerated failure. When three or four chains are worn out, you need to change the tire directly, if its wear reaches its limit by this time.

Chainsaw bar will wear especially hard in the areas where cutting occurs most often, usually on the underside of the guide bar. Any time the chain is changed, the bar must be flipped 180 degrees around the horizontal axis for even wear.

Video (click to play).

Now you know that you can troubleshoot a chainsaw with your own hands. To do this, you should always have a manual for the repair of chainsaws at hand. And in order to finally understand this difficult matter, we invite you to watch a video about repairing a chainsaw, which will help to consolidate all the acquired knowledge in practice.

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