The need to carry out the full trimmer-disassembly It's something that happens to every gardener, whether it's loss of power, the appearance of knocking, or the need to replace a piston group, understanding the design of a two-stroke engine is key to successful repairs, and it requires not only precision, but also a knowledge of the sequence of actions, because improper assembly can lead to fatal consequences for the unit.
Unlike the four-stroke analogues, two-stroke They're simpler, but they work in extreme conditions of high temperatures and rpm, which makes the accuracy of the gaps and tightness of the crankcase critical, and before you start to use tools, you have to prepare a clean workplace, because the smallest dust inside the crankcase is unacceptable.
This article will be your navigator in the world of small machinery mechanics, we will discuss the stages of dismantling attachments, removing the carburetor and silencer, and also dwell on the procedure in detail. crankcaseYou will learn how to properly diagnose the condition of bearings and glands, so that after assembly the trimmer works like a new one.
Workplace preparation and necessary tool
The success of the engine disassembly operation depends on 90 percent of the preparation, and you need not just a set of screwdrivers, but a specialized tool to work with threaded joints exposed to high temperatures. compression-removers for the flywheel, as attempts to knock it down with a hammer often lead to breakage of the crankshaft.
Organize the space so that all the parts can be decomposed in order of removal, which will save you hours of time when you reassemble them. Magnetic mats or numbered containers are ideal for fixing small items. Remember that some gaskets and glands are disposable, so you better plan their replacement in advance.
- 🔧 A set of end heads with extension cords and a rattle for unscrewing the crankcase bolts.
- 🔨 Flywheel Remover (a special tool for a specific trimmer model).
- 🧹 A compressor or compressed air cylinder to clean the parts from the sodium.
- 🧤 Marker for tags on tractors and wires, so as not to confuse the connection.
⚠️ Warning: Before starting work, be sure to drain the remains of the fuel mixture from the tank and carburetor, and also disconnect the spark plug to avoid accidental start.
Pay special attention to the cleanliness of the hands and tools. crank-and-shifterIt acts as an abrasive that instantly disables the bearings and cylinder mirror, and if you work in a garage, try to minimize drafts that can blow dust across disassembled nodes.
Dismantling of external equipment and life support systems
The first step is to remove all the attachments that prevent you from accessing the cylinder block. Start with a plastic casing, which is usually mounted on multiple screws. carburettor Carefully disconnect the fuel hoses, first squeezing them so that the gasoline does not spill on the hot parts of the engine or clothes.
Removing the carburetor requires attention to the gaskets. Often, an insulator is installed between the carburetor and the cylinder, which eventually bluffs and loses its leakiness. When unscrewing the nuts, try not to damage the hairpins, since the metal there is often soft and easily breaks. After dismantling the carburetor, remove the muffler, which can also be a source of problems, such as coking the exhaust window.
Then the ignition system comes in, and you take off the coil by remembering or photographing the gap between the magnet and the flywheel, which is critical for sparking. Clean the surface of the oily deposits using the same method. carbiclinic or a similar solvent that leaves no films.
- ⛽ Disconnect the fuel hose from the primer and carburetor, checking it for elasticity.
- 🌬️ Blow the fuel tank through the hose hole to remove possible debris from the bottom.
- 🔌 Remove the high-voltage wire by carefully turning the cap so as not to damage the insulation.
Now that the periphery is removed, you have the engine skeleton in front of you. Check the condition of the candle: if it's black and wet, it could indicate a rich mixture or ignition problems. If the candle is dry and light, maybe air enters the cylinder through the glands.
Removal of the flywheel and diagnosis of ignition elements
To access the crankshaft and stator, you need to remove the flywheel. This is one of the most important moments. The carving on the shaft often clings, so it is recommended to warm the center of the flywheel with a building hairdryer before unscrewing the nut, but not overheat the shaft itself, so as not to disturb the hardening of the metal.
Use a special removable, resting its paws in the magnets, and the central screw rotating to the end in the shaft. A sharp blow or jerk can split the magnets, after which the flywheel will have to change completely. After removal, examine the veneer: if it is crumpled, the angle of advance of ignition is knocked down, and the engine will work unstable.
Why can't the flywheel be removed?
Often it's not the rust, it's the cone landing. If the thread is ripped off or the skipper is hitting the end of the shaft instead of the cone, the flywheel will stay in place. Use the spacer if the shooter is short.
Under the flywheel, you'll find the crankshaft oal, which has a direct effect on the engine, if the rubber is cracked or has lost its elasticity, air suction is provided, and also check the surface of the shaft under the coil, if there is a shaft or rust, the new oal will not live long, and you may need to seed or grind the shaft.
⚠️ Warning: Never re-installe an old omentum, even if it looks whole. When removed, the geometry of the working edge is disturbed, and the sealing will be broken immediately after launch.
Halfing of the crankcase and extraction of the piston group
This is the most important step, which requires maximum concentration, and the engine consists of two halves of the crankcase, tightened by bolts around the perimeter, before unscrewing them, you need to remove the locking rings from the bearings, if any, and disconnect the throttle control from the carburetor assembly, if this has not been done previously.
Unscrew the bolts cross-cross, gradually relaxing the tension. When all the bolts are removed, the halves may not break immediately. Light tapping of a wooden bolt on the ledges of the crankcase will help to separate them. The main thing is not to damage the adjoining plane, as any scratch will lead to air sucking and the inability to adjust the engine.
☑️ Checklist before splitting the crankcase
After you have separated the crankcase will open in front of you. crank-and-shifterTake the crankshaft out with the piston. Notice the condition of the needle bearing of the lower head of the rod. If there is a backlash or a backlash, that explains the knocking in the engine. The piston is removed after the locking rings and the piston finger are removed.
| Component | Signs of wear and tear | Action. |
|---|---|---|
| Piston rings | Nagar, loss of elasticity, bullies. | Replacement of the ring kit |
| Bearings | Luft, rotating noise | Pressing new bearings |
| Salmon | Hardness, cracks, oil traces | Mandatory replacement |
| shatun | Flip-up, finger-back. | Replacement of a rod or a kneeshaft |
Look at the cylinder mirror. The presence of vertical drawings (zadirov) indicates overheating or working on a poor mixture. Small risks can be tried to erase, but deep bullies require the cylinder to be recycled for a repair piston or the entire cylinder to be replaced. Aluminum cylinders No niqasil coatings are to be squandered.
Defection of parts and cleaning from soot
After disassembly, all metal parts must be thoroughly cleaned of the coke and old gaskets. Use a soft metal brush and solvent to do this. Pay special attention to the exhaust window of the cylinder and the silencer channel, where coke deposits can reach several millimeters, significantly reducing power.
Check the geometry of the crankcase planes. Apply a ruler or a rod to the socket plane: if you see a lumen, you'll have to rub it on the abrasive paste glass or change it, and if you break the geometry, you'll depressurize and suck the air, making it impossible for the engine to work.
Use the stationery knife blade to carefully remove the remnants of the old pad from aluminum surfaces so as not to leave deep scratches.
Diagnostics of the piston group include compression measurement (if the cylinder is intact) and visual examination of the piston skirt. The presence of dark stripes on the skirt - traces of contact with the cylinder - indicates a violation of the gaps. Also check the condition of the bearing needle: it should rotate freely and not have traces of blue from overheating.
- 🧼 Soak the carburettor parts in a special cleaning liquid if you plan to maintain it.
- 🔍 Use a magnifying glass to inspect the surface of the shaft under the coils for microcracks.
- 📏 Measure the rod for a backlash in a vertical plane, shaking it with your hand.
Engine assembly and leakproofness check
The assembly is done in reverse disassembly order, but with the observance of important nuances. All bearings are recommended to be heated before pressing (for example, in oil or hair dryer), and oil oil oil oil oil oil oil oil oil oil oil oil will facilitate landing and prevent damage to the edges of the oils during installation.
When connecting the halves of the crankcase, make sure that the glands are correctly oriented (the working edge looks inward to the bearing). Tighten the bolts evenly, cross-cross, with a dynamometer key, observing the tightening moment specified in the manual. The bracket can deform the crankcase, and the under-tight will cause it to disconnect under pressure.
High-quality assembly of the trimmer engine is impossible without the use of new gaskets and glands, as well as cleanliness in the working area.
After assembly, be sure to check the engine for leakage, close the exit holes and inject air into the crankcase, dipping the assembled device into water or applying soap solution to the joints, and the appearance of bubbles will indicate the place of the sucker, which must be eliminated before starting.
What sealant should I use for a trimmer crankcase?
Use only high-temperature sealants that are resistant to gasoline and oil (usually red or black), apply a thin layer to avoid getting inside the crankcase, but it is better to use original paronite pads if they are designed.
Do I need to wipe a new piston?
Modern pistons from the factory are sized, lapping (break-in) occurs in the first 30-60 minutes of idling and with incomplete throttle, artificial laundry with abrasives is not necessary and can be harmful.
Why does the trimmer not start after assembly?
The most likely causes are: forgetting to plug the candle wire, clamping the fuel hose, incorrectly opening the candle or, worst of all, allowing air to suck through the crankcase gaskets. Check for spark and compression.