DIY chainsaw repair

Recommendation points

• Description of the construction and disassembly of the saw
• Solving problems with the fuel system and fuel preparation
• Muffler and air filter
• Typical piston malfunctions and their elimination
• Tire, chain, chain brake and lubricant
• Ignition system breakdowns
• Saw recommendations

In this article we will explain why breakdowns of certain parts of the chainsaw occur and how to fix them. If your saw stops starting or does not work as it should – do not rush to send it to the service. The simplest repairs may be enough to bring the instrument back to life..

Most chainsaw breakdowns are trivial. The imaginary sense of the complexity of the design disappears after the first complete disassembly, because the principle of operation of all the components of the mechanism is extremely simple and intuitive. Therefore, stock up on wrenches and sockets from 6 to 22 mm in size, slotted, cross screwdrivers, hex keys and a snap ring puller. Drain oil and fuel before disassembly, spread a clean cloth under the saw.

Description of the construction and disassembly of the saw

As a rule, it is not necessary to completely disassemble the saw when repairing breakdowns. Work is underway on one or more chainsaw units:

1. Chain, tire, clutch and overrun brake. Access can be obtained by removing the side cover on the right side, loosening the bar nuts and the chain tension bolt. The brake is in the lid cavity.
2. The clutch is located on the motor shaft to the left of the guide bar.
3. Chain lubrication system. The oil pump is located under the clutch basket or integrated into the crankcase housing.
4. The muffler is located in the front of the chainsaw, secured with two nuts.
5. The air filter is located at the top of the chainsaw, just under the cover.
6. The carburetor is located directly under the air filter, the connection to the engine cylinder can be made via an adapter.
7. The ignition system is located under the left side cover, in the cavity of which the manual starter is located.
8. Engine cylinder. It is attached to the crankcase with four screws from the bottom.

Solving problems with the fuel system and fuel preparation

Violation of the dosage of oil in gasoline leads to a drop in power, active clogging of the cylinder, and after that – to failure of the piston. The first signs of improper refueling are increased exhaust smoke or dry, crackling sound when the engine is running. The chainsaw is filled with A-92 gasoline with the addition of the recommended 2T standard oil (has a blue color) in a ratio of 50: 1.

The correctness of the preparation of the fuel-air mixture depends on the setting of the carburetor, which affects both performance and service life. A poor mixture does not allow the engine to develop power, under load the saw seems to “choke”, the engine may not start at all. Too rich mixture also causes problems when starting, it covers the cylinder and spark plug electrodes with carbon deposits, fuel consumption is increased. There are three screws on the carburetor for adjustment:

1. Screw “L” is screwed in clockwise until it stops, then smoothly released until the engine malfunctions disappear.
2. Use the “H” screw to increase the mixture supply if the engine responds poorly to the accelerator.
3. Screw “T” or “S” is used if the engine stalls or the chain is idling after adjusting the carburetor.

The carburetor can be correctly adjusted, but it is clogged, in this case it is completely disassembled and washed with gasoline, while the fuel filter, which is inside the tank, must be replaced.

Muffler and air filter

The clogging of the muffler or the air filter is explained by the lack of developed power in the engine, even without load it gains momentum very poorly. The muffler is soaked overnight in a solution of laundry soap and dishwashing detergent, rinsed well and dried. Do not clean the muffler with metal tools. The foam filter must either be washed too, or replaced with a new one.

Typical piston malfunctions and their elimination

The main difficulty in removing the engine cylinder is to twist the ignition flywheel and clutch. To do this, you need to block the piston: when moving to the top dead center, insert a rope with a dozen knots tied on it through the candle hole. The clutch has a left-hand thread and rotates either by a hexagonal lug or by two grooves, into which a slightly bored 17 key is inserted. The flywheel is fastened with a regular nut with a right-hand thread. When it is twisted, you need to lightly knock on the end through a wooden block..

The state of the cylinder-piston group must be checked every time the saw is disassembled. The presence of seizures and scratches on the surface of the piston and cylinder is a consequence of improper sawing and a signal for replacement. If only the exhaust port is scored, the saw has overheated multiple times. It is also necessary to check the presence of radial and oblique play in the bearings of the connecting rod and crankshaft..

The cylinder can be replaced separately from the connecting rod, for this you need to remove the retaining ring and knock out the pin. To replace the bearing of the connecting rod head, the latter is disassembled by unscrewing two bolts. The rings on the cylinder are changed either after the engine life has expired, or if there is visible deformation. Install the rings with the markings facing up. If the depth of the second groove is greater than the first, an annular expander is first inserted into it..

Tire, chain, chain brake and lubricant

When two chains are worn out, the drive sprocket needs to be replaced. The use of a worn sprocket affects the resource of the crankshaft bearings and is expressed in strong vibration, the chain also deteriorates faster. It is recommended to turn the tire as the working part is worn out.

Poor brake performance can be caused by excessive contamination of the space under the cover or general wear of the band spring. There are also frequent cases when, when the brake is applied, the clutch is destroyed from overheating and the entire unit needs to be changed.

Lack of lubrication on the chain can cause clogging of the oil pump channels; it must be washed in gasoline and cleaned with a fishing line. If the oil comes in too much during operation, you need to slightly tighten the adjusting screw of the oil pump. It happens that during operation the chain is dry, and when it is idle, oil oozes under the clutch. This means that the tightness of the oil hose is broken and must be replaced..

Ignition system breakdowns

The saw often fails to start due to the lack of spark on the spark plug. To make sure, unscrew the spark plug, put a wire cap on it, press it against the cylinder body and start the starter.

The spark may be missing for a number of reasons. First of all, check the contacts of the connection of the wires coming from the ignition module, strip them. Also inspect the flywheel for signs of damage to the magnetic circuit and if the gap between the module and the flywheel is broken. If the breakdown persists, replace the ignition module with a new one.

The reason for the lack of ignition may be the spark plug itself, check its suitability using a control one. The electrodes must be cleaned with sandpaper and wiped with a rag in gasoline.

Saw recommendations

To keep your saw from breaking less often, follow these tips:

1. Use only recommended oil and dosage.
2. Sharpen or change the chain in time.
3. Completely disassemble and clean the saw once a year.
4. Do not overheat the engine with prolonged load.
5. Change the fuel filter every 70-80 liters of gasoline used.

With the right treatment, your saw will last much longer.