Chainsaw Shtil-250: problems with the hot plant

I have Calm-250, old man, there was a problem: it starts up on a cold one without problems, you start it on a hot horseradish until you burn the unburned mixture through the muffler. I put a new candle, washed and cleaned the filter, washed the carburetor too. Anyway, the problem remains, please tell me how to solve it?


Checking the muffler

Most likely, the reason lies in the muffler, which is clogged with combustion products (deposits) or just debris. It is enough to clean it, and the normal operation of the chainsaw will be restored. To do this, it is best to dismantle this part and wash it using ordinary detergents (aggressive ones can be used). Then rinse the muffler thoroughly with clean water and dry with a hair dryer.

Muffler cleaning is usually beneficial.

Be careful when cleaning: carbon deposits contain carcinogens that, if ingested, can be harmful to health if they enter the lungs. The reason for the appearance of soot is the wrong ratio of gasoline and oil poured into the tank. Most users prefer to do this by eye. But it is not difficult to maintain the exact proportions: it is enough to use a disposable syringe without a needle of the appropriate volume.

Other reasons

Here, first of all, we mean the wear of the cylinder, piston, rings, and also the crankshaft bearings. The failure of these elements ultimately leads to a drop in compression (pressure) in the cylinder. You can check the state of the CPG along the way when you remove the muffler. After dismantling this part, you will see a window through which part of the cylinder is visible. If it shows scuffs or scratches, then it will have to be changed.

Parts for repair can be purchased at specialty stores or on the Internet.

Next, you need to check the compression. If there is no special device, remove the plug, plug the hole with your finger and pull the starter cord. With good pressure, the finger will be sucked inward. If there is a compression gauge, but it must be inserted into the spark plug hole. Also crank the crankshaft with the starter and look at the readings on the gauge. The normal parameter is 8-9 kgf / sq. cm (which corresponds to 0.8-0.9 MPa). The reason for the low compression may not necessarily be in a worn cylinder or piston: sometimes it is enough to replace coked rings.

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Identification and elimination of obvious malfunctions of the chainsaw.

To determine the reason why the chainsaw does not start or stalls when starting, it is necessary to troubleshoot the tool. The essence of the procedure is to consistently inspect the condition and operation of the main working elements of the saw motor. At this stage, we check:

  • Spark plug present
  • Fuel supply
  • Filter status
  • The operation of the breather of the stalling unit built into the fuel cap
  • Functioning of the outlet channel.

Checking the spark on the spark plug and eliminating the cause.

The first step in looking for reasons why your gasoline saw won't start is to check the spark on the spark plug. There are many factors that affect the performance of this element. However, the main ones at the initial stage of instrument troubleshooting are:

  • Incorrect carburetor adjustment
  • The presence of more than it should be, the amount of oil in gasoline
  • Clogged air filter.

All of them contribute to the formation of carbon deposits on the spark plug electrodes. In 50 cases out of 100, the saws do not start on a cold one due to the absence of a spark due to carbon deposits on the electrodes and their corrosion. As a result, the gap either decreases or increases.

Checking the spark plug with an idle chainsaw

It is quite easy to check for a spark. This will require:

  • Remove the lug of the high-voltage wire
  • Unscrew the candle
  • Put the tip back on
  • Lean the candle with the skirt against the cylinder
  • Start with a starter.

If a good spark is observed between the electrodes at the time of starting the engine of the chainsaw, then everything is in order with the ignition unit. If it is not there, then it is worth cleaning the element itself and checking the gap of the electrodes. If necessary, use a special probe to adjust the distance between the contacts.

For candles from different manufacturers, the distance between the electrodes may fluctuate. For some, it may be equal to 0.5 mm. Others have 0.2 mm. Therefore, carefully study the manufacturer's recommendations.

There may be no spark on the spark plug for other reasons. Of the main malfunctions that affect the poor start of the chainsaw and the unstable operation of the internal combustion engine at idle, from which the tool can stall, the following can be attributed:

  • Overflow of the spark plug channel with fuel
  • Lack of contact between the high-voltage cradle and the tip of the candle
  • Failure of the ignition unit.

How to start a cold chainsaw if the spark plug channel is constantly flooding with gasoline? To eliminate the problem while starting the tool, you can use the following algorithm:

  • Unscrew the candle with a special wrench
  • Wipe it with a clean and dry cloth
  • Dry for 20 ... 30 minutes
  • Remove carbon deposits with a file and adjust the gap between the electrodes
  • Drain the remaining fuel from the spark plug channel and dry it
  • Collect everything and try to start the mechanism.

As a rule, these measures are enough to start the chainsaw and get the job done. However, this last resort does not eliminate the main reason why the engine does not start or stalls - improper operation of the carburetor, which needs fine adjustment.

If there is no spark and poor contact of the high-voltage cradle with the spark plug tip, check the connection. The check can be done using a conventional tester. If a defect is found and its elimination, the chainsaw should start without any problems.

If the check showed that the contact is reliable, and the saw does not start further, look for the cause in the ignition unit. As a rule, a faulty unit cannot be repaired or restored. A complete replacement is required here.

We determine the availability of fuel and its supply.

First you need to make sure that there is a fuel mixture in the tank of a chainsaw that does not want to start, and it regularly enters the carburetor. With a full tank, we check how the mixture is fed through the gas line. We disconnect the fuel system pipe from the carburetor and try to pump it up. In the case of a complete order, when pumping up, gasoline will be supplied in jerks in accordance with the norms set by the manufacturer. Poor or no fuel supply may result from:

  • Clogged fuel line
  • Debris clogged fuel filter.

Often the reason for a poor start of the chainsaw can be a tank that is too full. In this case, you should pay attention to the presence of smudges under the saw case cover. If present, see the connection of the gasoline feed pipe to the carburetor. Most often, it is squeezed out by pressure when the tank cap is screwed on, which is filled under the very neck, which prevents the engine from starting.

The quality of the fuel mixture can also be one of the reasons why the chainsaw does not start. If, after completing the work, the remaining gasoline is not drained, and the tool is left for long-term storage (more than 2 weeks), then the processes of resinification and polymerization of the components will begin to occur inside the tank. What can cause carbon deposits on the piston, rings and cylinder liner. Therefore, always prepare the mixture only in the required amount before work.

Checking the condition of the fuel and air filters.

If everything is in order with the fuel quality, the chainsaw engine may not start due to clogged fuel and air filters. To diagnose these elements, it will be necessary to perform a number of manipulations associated with their dismantling.

  1. Disconnect the gasoline supply line from the carburetor
  2. Pump up fuel.

If there is little or no pressure in the branch pipe, disconnect the filter. Before that, free the tank from the mixture and remove the filter element itself. Dismantling is done with a wire hook. A clogged replacement cartridge that causes a poor starting of the chainsaw engine can be cleaned, but it is best to replace it with a new one. When using the tool in dusty conditions, it should be cleaned on a regular basis.

A clogged air filter can cause the chainsaw engine to run erratically, making it stalling or difficult to start. Dust and dirt deposited on the adsorbent material impede the flow of air into the system, make the fuel mixture so rich that it will sometimes be difficult to start the tool.

Checking the air filter is one of the first steps in finding the cause of a poor start.

Care should be taken when removing the air filter, as dust accumulated on the surface of the saw during operation can enter the carburetor. And this is fraught with more expensive repairs. After detaching the cartridge, thoroughly clean it of accumulated dirt and rinse it with the addition of detergent. Dry the element and place it in place just as carefully.

Checking the breather and cleaning it.

The breather is another element, from the improper operation of which the chainsaw may not start or stall during the sawing process. This element is located on the fuel tank cap in the area of ​​the air hole. This is a kind of valve that does not allow gasoline to flow out and equalizes the air pressure required for the free flow of fuel into the carburetor.

If the breather is dirty, the working chainsaw stalls, and when started, it refuses to start. The thing is that air stops flowing through the hole. As a result, a negative pressure (vacuum) is created inside the fuel tank, preventing the flow of gasoline to the carburetor.

Defining the problem is pretty straightforward. Disconnect the fuel hose from the carburetor and see what happens to the gasoline. If it flows freely in a good trickle, then everything is in order with the breather. If it is absent or it flows weakly and intermittently, then the reason is identified - the breather is clogged with dirt. You can solve the problem by cleaning the air hole with a regular needle or a powerful jet of compressed air.

Checking the outlet of the chainsaw.

One of the reasons that a chainsaw does not start well may be a clogged exhaust channel or its muffler. At the same time, a drop in power is noted in the process of sawing sawn timber and logs. This is most often due to resinous deposits on the spark arrestor or muffler channel, which are formed during the combustion of a poor-quality mixture of gasoline and oil, which impedes the removal of exhaust gases.

Resonator clogged with carbon deposits can cause poor starting of the gasoline saw.

Eliminate the cause of the poor start of the chainsaw, in this case, you can remove the accumulated combustion products. To do this, perform a number of manipulations:

  • Remove the muffler by unscrewing the screws
  • Remove the cooling pad and gasket
  • Remove the spark arrester
  • Disassemble the resonator housing
  • Wash all elements from carbon deposits with detergent
  • Let them dry completely
  • Collect everything in reverse order

To prevent dust and sand from entering the cylinder when cleaning the muffler, cover the outlet of the chainsaw engine with a clean rag.

What if the chainsaw won't start further?

If the initial inspection did not give anything or the defects were eliminated during the search, and the chainsaw does not start further, then you need to look for more serious reasons. It is best to identify and eliminate such breakdowns in a service center. However, with experience, you can find and eliminate them yourself. What to diagnose and check?

  1. Compression in the cylinder
  2. Compression in the crankcase
  3. Carburetor work.

In the first case, checking the compression in the cylinder will allow you to find out the state of the cylinder-piston group (CPG) of a chainsaw that does not want to start cold. For this you need a compressometer. The device is screwed into place of the spark plug and the engine is idle. Measurement of readings allows you to judge the state of the CPG. In the absence of a compression gauge, the compression in the cylinder can be determined offhand as follows:

  • Place your finger on the candle hole
  • Try starting your chainsaw engine.

By placing your finger on the spark plug hole and pulling the starter, you can check the compression in the cylinder.

If you feel that your finger is pulling strongly into the candle channel, then everything is in order with the compression. The absence of a vacuum in the chamber indicates a malfunction. The cylinder-piston group needs a more detailed inspection, which will give an idea of ​​the condition of the piston and cylinder, piston rings and bearings.

The chainsaw may not start on a cold one due to the lack of compression in the engine crankcase. The main reason for this is damage to the gasket placed between the cylinder and the crankcase. It is quite easy to detect the lack of compression:

  • Disconnect the upper tube from the carburetor
  • Pour gasoline into a regular cork
  • We immerse the removed tube in the fuel
  • We pull the starter several times.

If the fuel from the cap is sucked in when starting the chainsaw starter, then everything is in order with the compression. If not, see the gasket.

If the fuel is drawn in, then everything is in order - the gasket is intact. Otherwise, you will have to purchase a repair kit and replace it. How to do this watch the video, why the Chinese chainsaw does not start:

Starting the tool can be complicated by improper operation of the carburetor or its breakage. It often happens that during the sawing process, the fastening screws are loosened and air is sucked into the cylinder. Check that the carburetor is securely fastened. Inspect it for fuel leaks. There can be a lot of reasons for the malfunction. It is possible to pinpoint the malfunction, eliminate it and fine-tune the carburetor only at a service center.

After going through the step-by-step troubleshooting of the chainsaw engine, you can find the malfunction, fix it yourself and successfully start your working tool. Do not take on jobs that you are not sure of. Entrust the troubleshooting to specialists from the service center.

Chainsaw stalled and won't start

If the tool stalled and does not start, first check the presence of fuel in the tank. Oddly enough it sounds, but many people forget about it and when a similar situation arises, they immediately try to repair the instrument, which can lead to serious damage.

In a situation where the saw has stalled, and there is still gas in the tank, you need to evaluate how the saw has worked up to this point. Maybe at the last moment, there was an extraneous sound, grinding, ringing, a loss of power, or the instrument stopped abruptly. All this will allow a preliminary assessment of the situation.

Engine jammed

Quite often, there is a situation when the saw worked and stalled abruptly, the cause of which was the engine jamming, which in turn occurred as a result of a broken piston skirt, destruction of the crankshaft bearing, protrusion of the piston pin cork ring or piston ring fracture.

A jammed engine can be easily identified by pulling on the starter cord.In the event that the starter does not turn, most likely, it has jammed, and further repairs are possible only at a service center.

Broken fuel line

During the operation of the chainsaw, vibration occurs, which can cause damage or breakage of the fuel line of the chainsaw. In this case, the chainsaw will stall and it will be impossible to start. To diagnose a malfunction, you need to conduct an inspection and determine the presence of fuel leaks.


Overheating of the engine during operation can cause the saw to stall and not start. Overheating is quite dangerous, as it can cause the piston to melt in the cylinder and the engine to jam. At the first cases of overheating, it is worth diagnosing the tool for the presence of extraneous air suction into the engine, and adjusting the carburetor.

Air leaks, as well as incorrect adjustment of the carburetor, affect the maximum number of engine revolutions and its lubrication, which in turn causes overheating and wedging of the tool.

Recommendations for storage of fuels and lubricants

Fuel with an oil component can be stored in a metal container for no more than one month. Old gasoline / oil mixtures tend to form coking resinous deposits that limit the mobility of the piston rings.

Water enters the fuel system not only with gasoline, but also forms condensation on the inner walls of the carburetor at high temperature differences.

The presence of water in the fuel is manifested by white smoke from the muffler, interruptions in the operation of the engine, and its complete stop when ice forms in the system.

Watch the video: 2 Stroke Carburetor. How to Tune. How it Works. Basic Principles

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