Motor designer" or how to assemble an engine correctly? part 2

04.10.2018

STK pistons and SWP rings are the best for domestic cars. The upper segment of the cylinder-piston group in a four-stroke engine can be divided into two main sections:

• cylinder head;
• cylinder-piston system.

They both require special attention and strict implementation of certain steps to ensure the correct operation of the entire power unit. In other words, no matter how “pumped” and modernized your car is, no matter what the latest electronics are introduced into its electrical network, the quality of ride and operation of the entire car depends primarily on the condition of the cylinder head, piston and the cylinder itself.

To write this article, the burnt-out piston was replaced with a special piston from the STK kit. Kit includes rings, pin, retaining rings and installation instructions. Pistons are available in sizes A, B and C to match your cylinder size when the system fails and requires component replacement.

Piston STK 82.0 with Priora anti-friction coating

Piston group assembly

1. Before starting work, it is recommended to preheat the piston to a temperature of +240 degrees, but if this is not possible, you can insert the piston pin on a cold one.
2. Before connecting, thoroughly wipe the hole of the connecting rod, piston, and piston pin from dust with a rag.
3. Next, you should lubricate the holes and piston pin with machine oil.
4. It is important to install the piston and connecting rod correctly in relation to each other. The symbols will tell you which side to place the piston on. The piston may have special recesses for the valves or an arrow on the inner surface of the piston, which should point forward along the

   
   direction of movement of the machine. The connecting rod has special overlays in the form of letter designations, which should also face forward in the direction of movement.

5. Connect the piston to the connecting rod using a connecting pin. Align the piston holes with the hole on the connecting rod and insert the piston pin. The piston pin must not fit into the hole freely. It will be necessary to apply a certain force by lightly tapping the end of the finger with a hammer. Do not tap directly on your finger, as this may lead to the formation of a burr. To prevent this from happening, use a wooden block to hammer in your finger. When driving in a finger, the piston should not lie on a hard or metal surface; it is advisable to lay it on a soft rag or a wooden block.
6. After the pin has entered, you need to secure it with locking rings in special grooves in the piston.

Cleaning

When disassembling, you need to clean all old gaskets and sealing surfaces of oil, dust and small debris. The cylinder base, the top and bottom surfaces of the cylinder itself, and the bottom surface of the head, which fits tightly to the cylinder, also need to be cleaned.

A razor blade is successfully used to clean large and particularly difficult areas. However, be careful not to leave deep grooves or scratches in the surface. Also, watch your fingers; knife blades slip off metal surfaces very easily.

Things to remember:

1. Firstly, do not think that with an ordinary blade you cannot leave a groove on the surface of the durable metal of the cylinder - practice shows that anything is possible;
2. Secondly, very often sandpaper is used to simplify and speed up the cleaning procedure; this cannot be done, even “zeroing” is prohibited, since the resulting surface (no matter how smooth it may seem) will not create an absolutely tight connection with another surface.

Remove the remaining gasket carefully, being careful not to gouge or scratch the sealing surfaces.
Final cleaning usually involves using carburetor cleaner or a similar chemical cleaner (gasoline, solvent, or mineral spirits based) and a rag to achieve completely clean, mirror-like, and flat surfaces.

Causes of piston group wear

Constant operation of the machine inevitably leads to damage to the steam generator. Like any other element of the power unit, pistons wear out due to obsolescence or due to overheating caused by a disruption in the combustion process.

What causes piston crown wear?

Seizures on the piston bottom are formed due to clogging or deformation of the oil nozzle, installation of elements with different sizes, or a malfunction in the cooling system.

Pistons on used cars often show impact marks. They are caused by an overly large piston protrusion or improper adjustment of the end side of the cylinder head. This also happens due to engine oil deposits on the head of the element, an unusually narrow gap in the valve drive and incorrect installation of the gas valve phases.

Damage is also determined by metal deposits on the elements. This happens when the injector is faulty - in this case, the injection quantity is determined incorrectly by the system. This will also indicate insufficient compression, late or early ignition.

If cracks are observed on the piston crown and in the combustion chamber cavity, this is evidence of a faulty injector or insufficient compression. This is also possible if the engine is not properly chipped, when they try to increase the power of the unit through modernization.

checking the piston for wear

Causes of ring damage

As a rule, this happens due to erosion of the material in the ring area caused by improper installation, excess fuel in the combustion chamber, or violation of the thermal gap between the piston and its cylinder. The same thing happens with strong axial wear of the piston grooves and vibrations.

Another reason is radial wear associated with mixing. Any disturbance in the fuel combustion process, as well as insufficient compression pressure, lead to such a malfunction.

Axial wear is also possible as a result of simple contamination, when soot particles stick in the groove due to insufficient filtration. This could be sawdust, blast residue, or any other abrasion product.

Why is the piston skirt damaged?

Several reasons contribute to this - deformation of the connecting rod, crookedly installed cylinders, excessive play of the connecting rod bearing. In these cases, an asymmetrical, clearly visible spot forms on the skirt.

There may also be 45-degree burrs and other friction marks caused by an overly tight pin fit or an error in the installation of the hot-pressed connecting rod. The reason is also called a low compression percentage, misfires, and dilution of the oil with gasoline.

The main signs indicating resource depletion:

• blue exhaust color;
• active carbon deposits on spark plugs;
• drop in engine power;
• unstable operation of the unit at neutral speed - quickly determined by strong vibrations of the gearshift knob.

And, of course, the most important sign is increased engine oil consumption.

Progress:

First you need to make the base of the nozzle. To do this, use a grinder to cut out a square with a side of 100 mm from a metal plate. You need to mark it in such a way that there is a hole exactly in the center (at the intersection of the diagonals). To do this, from the center of the selected hole perpendicular to the short side of the plate, measure a distance of 50 mm and mark the trimming line.

We cut off the excess and get a square of 100 mm x 100 mm. Now you need to slightly round the corners and drill out the central hole for the trimmer shaft.

Round the corners and drill the central hole for the trimmer shaft

We cut the metal sheets, measuring 8 cm from each end. We get 4 blanks with ready-made holes.

These blanks must be shaped into knives. To do this, we mark the cutting line by eye (special precision is not required), fasten all 4 blanks together and grind off the excess.

As a result, we get knives of the same weight and size; they can be sharpened a little on one side. Now all the parts of the homemade trimmer attachment are prepared, you can start assembling.

We put a small washer on the screw and insert it into the corner hole. We put the knife on top, placing the sharpened side in the direction of rotation of the trimmer shaft. Next comes a large washer and a nut, which is not tightened so that the knife rotates freely. We attach the other 3 knives in the same way.

The end of the screw must be riveted so that the nut does not fly off.

The nozzle is ready. It is installed with nuts to the ground and secured in the same way as the three-bladed knife that comes with the trimmer. When colliding with a stone, the knives fold and go inward a little.

This idea was proposed by our regular video author Tatyana (Tula region). You can see in more detail the entire process of making such a trimmer attachment and learn some of the nuances by watching the video she prepared.

When working with a trimmer, it is important not to forget about safety precautions when using any attachments, especially homemade ones.

Where to place the piston arrow on 2- and 4-stroke engines | Pin offset (Desaxial) | Dnepr/Ural.

We invite you to discuss this idea in the comments to the publication. Share your thoughts with us and also tell us about your successful decisions.

Without taking either side of this heated (literally and figuratively) debate, let me show you one of the latest models of lawn mowers from the German company Robert Bosch. It has both a deflecting knife and an arc-shaped bracket, which prevents the knife from “striking” against objects not intended for mowing. I show a general view of the brush cutter and the knife itself, in two positions. General view of the brush cutter

Good evening everyone! Exactly three years have passed since the discussion of the “acute” problem for the trimmer. Over the past 1000 days, a clear picture has emerged: “Glory to the author - the craftsman who is conducting an experiment on himself to achieve the yield point of the metal from which these knives are made.

He has every right to risk his own health.” Nowadays, in stunt films you can often see the phrase - “Don’t try to repeat movie stunts that were performed by professional stuntmen.” The very first article should have ended with approximately the same phrase:

» Dear summer residents. This is my personal experiment. If you are not confident in your locksmith skills, please do not repeat it. AND THE MOST IMPORTANT THING - I am not responsible for the operation of the tool made in the wake of my article.” And one last thing. Do I see errors, judging by the photographs, of the implementation of this tool.

Alas, the author of this device does not even know how the hole for the shaft should be made.

I inform you that the distance from the point of the hole closest to the edge of the plate to the very edge should be NO LESS than the diameter of the hole itself. Mechanical engineering students will learn this truth no later than their second year at the institute. What do we see here? A thin isthmus reminiscent of a narrow PEREKOP, making a peninsula out of Crimea.

This is a priori the place that is weak in this design - it experiences the same loads as other knives, and the “dig” there is very thin. Where it is thin, there it is... I would like to hope, and quite sincerely, that over these three years this isthmus has not undergone loads comparable to the yield strength of this metal, but rather the alloy from which the perforated plate is stamped.

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How to choose new pistons when purchasing?

There is a wide range of these products on the domestic market. It is usually difficult to choose between pistons manufacturing technology - forged or cast. The first varieties are much more expensive. The second ones are more common. Before making a choice, you need to understand whether the car requires an increase in standard power. If yes, then definitely give preference to forged analogues.

Pistons are regularly subjected to high loads, so the performance of the internal combustion engine directly depends on their quality. An important parameter is also the weight of the product. Manufacturers try to make them light, but at the same time durable.

When choosing, it is recommended to pay attention to the German brands Kolbenschmidt, Mahle, Prima . The Russian Motordetal-Kostroma and STK have proven themselves to be quite good at producing such products.

Piston 6D16 ME072549 (set of 6 pcs.) for 6D16 engine on Mitsubishi

How to Install a Piston on a Trimmer

How to correctly install the piston on the trimmer

Replacing the piston group in a chainsaw or trimmer

Repairs of this level must always be balanced. How to correctly install rings on a two-stroke piston In installing rings on a piston. In such small engines operating at high speeds, replacing the first piston, which is burned out or jammed, does not give a long result and, if necessary, you need to change the entire piston group . Therefore, you need to consider whether to continue to use this saw or purchase a new saw.

If it is a professional model, then such repairs are worth carrying out, but if it is an old household model like a Husqvarna 40 and it has worked for more than ten or twelve years, it is not profitable to repair it. Because repairing it will cost so much. the same as purchasing a new saw, albeit not a Husqvarna, but a PARTNER P350XT CHROME, costing 165, will definitely be enough. Moreover, such saws are sold by Husqvarna, since PARTNER is its subsidiary.

But if you still decide to repair a chainsaw or trimmer, then you need original spare parts, which are not cheap. If the engine is used correctly, the first repair may not occur soon and only the piston ring or rings will have to be replaced, depending on the model. But if the saw jams, then it is necessary to change the entire piston group - the cylinder, piston and rings.

It should be noted that Husqvarna 136/141 chainsaws have approximately a service life of 500-600 hours, Husqvarna 340/350. 1000-1200 operating hours, professional chainsaws at least 2000-2500 operating hours, subject to strict adherence to the operating instructions. In fact, you cannot rely on these figures, since the actual resource may differ significantly, both up and down. But approximately we can say that semi-professional saws work 3-4 times longer than amateur ones, and professional ones up to 10 times or more.

Of course, nothing lasts forever, but it’s one thing if you change the piston group after many years of operation and it has worked its hours and has fully paid for itself, but another thing is that this saw was filled with, for example, only gasoline, without oil, and it jammed. This saw has to be repaired, since all other parts are normal.

Many companies deliberately inflate the cost of spare parts so that new models can be purchased. For chainsaws and trimmers, for example, from Stihl, spare parts are available in a larger range than for Husqvarna. Therefore, when choosing a specific model, find out how things are with spare parts. RVT

How to properly install rings on a two-stroke scooter piston

There is nothing complicated about installing rings on the piston of a two-stroke scooter, as well as a four-stroke scooter, and many people know this. But most scooter riders who have only recently acquired such equipment have no idea how to replace the piston on a scooter, how to correctly install the rings on the piston, where the arrow on the piston should point, and much more. In this lesson, I will tell you how to properly put the rings on the piston and assemble the piston in place. Since we have already talked about four-stroke engines before, here we will talk only about two-stroke engines. So, our piston is worn out and requires replacement. First of all, the rings and piston , and usually only them need to be changed. If the piston is severely worn, it is necessary to bore the cylinder. It is also bored when the piston jams in the cylinder, forming deep scratches on the walls of the latter. There is nothing wrong with this, and if your new cylinder has been properly bored (which will only cost about 10), it will need a repair set of rings with a new piston. Such rings are marked 0.25. The second boring is 0.5, respectively, etc. to one. After purchasing a piston, it needs to be assembled. In the kit, as a rule, you will find the piston itself, two compression rings, a third thin corrugated ring (more on its purpose later), a piston pin and two piston pin retaining rings

How to change the piston on a Trimmer!!!

In this video I will show you how to quickly change the piston on a trimmer yourself. How to correctly install rings on the piston of a two-stroke scooter Published on August 25 I will change them on a trimmer.

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How to install the piston correctly

The bastard shows and tells how to install the piston

into the cylinder on a scooter and motorcycle Now about the third ring in the set. Its purpose is to spring the lower compression ring. It installs it directly under it, and usually does not provide any benefit during operation. You can throw this ring away or you can put it in, it makes no difference. Many piston manufacturers do not include it at all. It's time to put everything back in place. Depending on the scooter model, compression rings may be the same or vary in thickness and cross-section. Most pistons for Honda scooters, for example, have different rings, where the upper one is thinner than the lower one and has a different cross-section.

You should definitely pay attention to this when installing; the top one is thinner and ground at an angle.

Also pay attention to the inscription on the ring (usually the letter T or repair size); the inscription should always be on top, that is, opposite to the finger. First you need to put on the bottom, then the top. There is no need to stretch or bend them. These manipulations must be carried out carefully.

There are locks in the grooves for the rings that prevent the rings from turning during operation, so the ring gap must be in these locks, otherwise you will not stick the piston into the cylinder.

And the last important point is the arrow (1) on the bottom of the piston or the inscription EX. Both the arrow and the inscription must be directed towards the exhaust (2). In this case, the ring locks will be located on the side of the reed valve. If the locks are placed towards the exhaust, the piston will not last long, the rings will be pulled into the exhaust port and gradually grind it down.

During all manipulations with the piston, it is imperative to put a rag in the crankcase window so that nothing inadvertently gets in there; we still need a crankshaft with bearings.

When installing the piston pin , pay attention to the condition of the separator (bearing); it may need to be replaced. Before installing the piston pin , install the snap ring on one side before installing the piston (usually on the side where you will not be able to fit the pin and the second snap ring in). Then place the pin with the bearing and the second retaining ring; when fixed in the groove, it will make a certain click.

That's all, now put on the cylinder, not the piston (remembering to check the condition of the gaskets and lubricate the piston and cylinder walls with engine oil), the cylinder head and tighten the bolts one by one in a cross pattern.

MTD-600 trimmer repair advice.

Good day, dear friends!

Today I want to share useful information about trimmer repair, which was kindly provided to me by our reader Yuri. With his consent, I am publishing this, in my opinion, very useful information.

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I’ll share how I repaired trimmer (ignition problems), maybe someone will find it useful.

At first, nothing is clear, the trimmer simply won’t start, it won’t even sneeze.

1. How to Correctly Install the Piston on a Chainsaw. I checked the compression (to exclude damage to the mechanics in the cylinder, rings, connecting rod, etc.) - the compressor shows 10 bar after a couple of jerks - this is quite enough, the cylinder- piston -rings are in order.

2. Gasoline is supplied through the carburetor - the spark plug is wet and the top of the piston is wet.

3. The spark plug is clean, the gap is 0.6 mm. When cranking, a spark occurs - we temporarily connect the inverted spark plug (its threaded skirt) with a wire to the cylinder and turn the starter - everything is in order.

4. There is compression, there is gasoline, there is a spark, but it does not start - this means there are problems with ignition (ignition timing). But the ignition timing on trimmers/chainsaws and similar two-stroke engines is not adjustable! Therefore, we disassemble the trimmer and remove the engine from the shaft with the starter. The magneto opens - a coil with two terminals-contacts and with two “cheeks” of the core, which at some point are closed by a magnet built into the flywheel to which the starter clings when cranking. It was discovered that this short circuit (it can be seen is the combination of both ends of the magneto core with such well-defined magnet areas in the flywheel, the gap there is a fraction of a millimeter, while in other positions of the flywheel a few millimeters remain above the magneto) does not coincide with the TDC ( top dead center) of the piston (this point is easy to find by turning the shaft, observing the piston into the hole in which the spark plug is turned out).

Here comes the breakdown! The magneto should close somewhere near “top dead center”, but it closes when the piston has gone down somewhere! We unscrew the nut that presses the flywheel to the tapered shaft. It is detected: the pin has been cut off, which fits into the grooves on the outside of the shaft cone and on the inner cone of the flywheel and which rigidly mates them in one position. The flywheel "turned". Most likely, someone pulled the starter with too much stupidity, so they tore off the flywheel, knocking out the ignition ( the trimmer is American, it should be easy to start even by a child, no force is needed, but there are tractor drivers with experience in starting a diesel starter, for them this technique will be a little delicate) .

5. If there is no standard pin, then you need to make it yourself: a small plate, curved in the shape of a “U”, so that with its “horns” it fits into two grooves in the flywheel, and with its curved part into a wide groove on the conical shaft. Its size is selected experimentally so that the flywheel is lowered on the shaft and securely fixed.

We check the coincidence of the magneto and “TDC” closures, tighten the flywheel nut, assemble the trimmer, and start it according to the instructions.

Everything should work.

Many thanks to Yuri for such useful information!

Source

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What is a fuel mixture and how to prepare it?

Although many people simply pour gasoline into the tank first, and then oil, and lightly shake the mower, we will do everything right for the new unit. To prepare the fuel mixture for the Fubag lawn mower, 92-octane gasoline and a special semi-synthetic motor oil designed for 2-stroke air-cooled engines are used.

Please note that oil for water-cooled engines (boat engines) and oil for 4-stroke engines are not suitable here - they form carbon deposits on the spark plug, clog the exhaust port and damage the piston. For our engines, we recommend Fubag 2T Extra semi-synthetic oil - an optimally selected high-quality composition.

The recommended proportional ratio of oil to fuel mixture is 1:40, that is, for 1 liter of gasoline you need approximately 25 grams of oil, this can be exactly the volume of a standard cap from an oil container. In the case of a fuel mixture, oil can ruin the porridge, because... excess slightly increases the smokiness of the mixture during operation, and therefore carbon deposits.

Not adding oil is also not good, because... Lack of lubrication critically affects the service life of 2-stroke engines.

Before refueling the Fubag gas trimmer. This mixture must be thoroughly mixed in a separate canister, and only then poured into the gas tank. The quality of mixture preparation directly affects the engine life of a gasoline trimmer. Therefore, do not use fuel mixture prepared more than two weeks ago. This may lead to premature failure of the unit.

Pour the mixture into the gas tank, it is advisable to fill it no more than 80%.

On our trimmer, the tank is translucent, which makes it possible to monitor the amount of mixture by eye. it is very comfortable!

By the way, there is a reminder on the fuel tank - so you won’t forget.

EXPERT TIP: Under no circumstances should you store gasoline in a plastic water container. When mixing the fuel mixture, a static charge accumulates and a spark can be caught.

— Assembling the braid

So, first you need to properly assemble the lawn mower. It's very simple.

1) Connect the rod and the motor. To do this, we align the rod relative to the engine so that the spindle is located in the same plane with the engine fuel tank.

2) Install the rod flange into the engine and secure it with 4 screws.

To do this, you need to unscrew the thumbscrew on the top cover of the fastener. And remove the top cover. Next, insert the handle into the fastener, install the cover, and tighten the screw. We put the control handle on the pipe and fix it with a screw. On this trimmer, the adjusting screw allows you to adjust the handle to suit the user: you just need to loosen the “thumb” and move it to the required distance, and then secure it.

READ How to remove the pole from a Patriot trimmer

Connect the throttle cable to the engine and insert its end into the throttle joint. Connect the red wire of the control handle to the red wire of the engine, and the black wire to the black wire.

9) Holding the rod, twist the spool of fishing line counterclockwise until it stops. All that remains is to install the two-shoulder belt. Attach the shoulder strap carabiner to the shoulder strap attachment ring. We adjust the position of the ring on the rod of the product and fix it with the fastening screw. Adjust the length of the shoulder strap.

What is the difference between a good trimmer and a bad one?

The main difference: the level of assembly and manufacturability. To do this you need to disassemble the engine. In the figure we see that there is a grid on the engine cylinder mirror. The mirror is finished with final honing. We see a network of small grooves that retain oil, which creates ideal conditions for lubrication of the piston and removal of excess heat.

The cylinder mirror is chrome-plated - this application strengthens the surface layer of the cylinder mirror made of porous chromium, which increases wear resistance and service life, reduces friction and increases the specific power of the engine. Therefore, this particular engine will last a long time even under intense load.

Installing piston rings

1. Before installing the rings on the piston, you should make sure that the piston grooves are clean; if necessary, wipe them with a clean rag.
2. The rings are installed from top to bottom, that is, the lowest oil scraper ring is installed first, then the compression rings.
3. When installing the oil scraper ring, you need to make sure that the locks

   
   the ring itself and the inner spring were on opposite sides of the piston.

4. If the rings have letters on them, place the rings with the marked side facing up. To facilitate installation, the piston can be lubricated with machine oil. Compression rings can have different widths according to the width of the bore on the piston.
5. After which it is worth unfolding the rings so that the locks are located at an angle of at least 120° from each other. Otherwise, compression may be impaired.
6. After installing all the compression rings on the piston, you should make sure that the rings rotate smoothly in the grooves, without jamming or scuffing.

Receipt

The pistons can be removed with any tool (even by hand), and in any case it will drop out as a pick-up item.

Piston power

Pistons can be powered in various ways:

• If the red wire is directed directly to the piston, and directly behind it it has the shape of a straight mowing line. The wire does not automatically bend towards the piston.
• If right next to him there is a block charged with a red stone (of any strength) or a red torch.
• If the charged block is located diagonally above the piston, or two blocks above it. There is no physical contact with the piston, so the piston “does not realize” that it is charged until it is updated by the neighboring block (the phenomenon of quasi-connectivity). Many block update sensors are built on this principle.
• The pistons are considered a non-solid (“transparent”) block, so it is impossible to transfer energy through them.
• Pistons cannot be charged from their head side. However, if the piston is directed upward and pushes a charged block there, then due to quasi-connectivity (see above) it will be charged with it.

Preparation for the procedure

You need to start by cleaning the exterior of the scooter from dirt, sand, and dust. The work itself must be carried out indoors, where there is no risk of debris getting inside the mechanisms from the outside. Operations may be carried out outdoors, but subject to the following conditions:

• the air temperature should be 18-25 degrees;
• little or no wind;
• the presence of a flat, hard surface for repairs - concrete or asphalt are best suited;
• It is not recommended to open the inside of the scooter for at least two hours after turning off the engine for safety reasons.

For fastening, you will need to prepare a box with cells for each type, so as not to lose or mix up the varieties. The work may take about an hour depending on your skill level. If you lack experience, it is better to call another person for help and carefully record what was removed (and in what sequence) in order to reassemble the vehicle correctly after everything.

Signs of a CPG malfunction

To determine the breakdown of the piston group, you do not need to have complex measuring instruments. It is enough to pay attention to the following symptoms:

• the ringing of piston rings is heard;
• The scooter does not start on the first try. You have to perform the operation several times to achieve the result;
• rapid emptying of the gas tank due to excessive fuel consumption;
• noises are heard in the cylinder/motor that were not there;
• the vehicle operates unstably at idle speed;
• general reduction in power;
• sudden shutdown.

Additional signs include too much smoke and lack of resistance when trying to start the scooter's engine. After disassembling (detailed list of actions below) the motor can be seen on the piston cylinder with black traces - this is carbon deposits. This indicates a loose fit of the pistons to the cylinder walls, as a result of which gases constantly escaped from the inside, which reduced the overall pressure.

Old piston with signs of carbon deposits

In the case of a four-stroke engine, the signs of a CPG failure are slightly different:

• presence of thick black/blue smoke;
• increased oil consumption;
• change in power (this indicator can only be determined during diagnostics, since on a 4-stroke engine the change in parameter may not be immediately noticeable);
• inability to start the scooter the first time even with a cold engine.

If these problems are observed, it makes sense to disassemble the vehicle in order to reduce repair costs in the future due to malfunctions of other parts caused by the lack of replacement of the CPG.

What tools are needed to replace pistons

The following set of tools is required to replace a piston engine:

• spanners;
• heavy hammer;
• a piston ring remover, which is a pliers - if there is no such device, you can use a regular thin flat-blade screwdriver;
• vice;
• burner;
• micrometric bore gauge;
• torque wrench;
• a guide sleeve and a mandrel with a handle and a threaded hole at the end of a special or homemade design - can be turned on a lathe;
• a drift to the size of the piston pin - must go inside the hole;
• file;
• wooden blocks;
• ratchet with heads of different sizes.

Of course, you need to prepare a new set of pistons. It is recommended to pay attention to the quality of the rings and the appearance of the packaging - manufacturer’s name, material. The rings should be marked to indicate the top side. In order to maximize the service life of the pistons, an anti-friction coating is applied to the skirts of the products. For example, a suitable option is Modengy solid lubricant.

How to install a piston on a scooter: remove the old one, install a new one

Getting to the piston cylinder will be easy if you follow the instructions. You need to start by removing the plastic lining of the scooter, and then disconnect the wires. The oil hose is disconnected, and the motor itself is removed by unscrewing the fasteners. The plastic cover should be set aside so as not to crush it due to careless movement.

To get to the piston, you ultimately need to remove the cylinder head, and then the cylinder itself.

Dismantling the piston itself is carried out in the following sequence:

1. remove the CPG mounting bolts along with the head and gasket. Each bolt must be unscrewed in a criss-cross manner (diagonally) to avoid damaging the threads - installing the piston back requires using the same method. This will also prevent unwinding without the participation of the owner;

2. directly dismantling the cylinder using upward movements - if you can’t pull it out, it is recommended to knock with a light wooden object. The product may become stuck due to the deposits listed above;

3. turning the crankshaft for maximum piston lift. Be sure to cover the crankcase hole with a rag to prevent dirt from getting inside;

4. you need to remove the retaining ring in order to remove the piston pin;
5. In case of jamming, you need to use liquid to remove carbon deposits. An alternative is carburetor cleaner. As a result, after soaking, all plaque is easily removed, similarly with rings;
6. cleaning ring grooves.

Step-by-step video on how to remove the piston from a scooter:

You will need to inspect the needle bearing for signs of burning, indicating wear of the part. If they are, a change is required immediately. Installation of a new CPG will not be effective for long in the absence of proper care.

Needle bearing

You should also pay attention to the following factors:

• if there is displacement of the needles inside the cage, the product as a whole is unusable;
• violation of geometry also indicates the need for replacement;
• There should not be much play when moving in the upper head of the connecting rod. In normal condition, the bearing simply moves freely.

As a result of changing the needle bearing, you can install a new piston for the scooter. Installation is carried out in reverse order. Several features of the procedure must be taken into account:

Repairs can be carried out using a special kit containing all the necessary tools:

• piston ring remover (pliers);
• piston groove cleaning device;
• L-shaped screwdriver.

All this can be found separately. The main thing is to follow the dimensions that will suit a specific scooter model.

Step by step video on how to install a new piston on a scooter:

Usage

If the piston is powered by a red stone signal, its wooden head will extend, which will try to push out the blocks in front (if they are movable and there are no more than 12 of them). The extension lasts about one and a half redstone ticks (0.15 seconds) and is accompanied by a sound that can be heard at a distance of 15 blocks from the piston along any axis. At the same time, if there are entities on the way, then if there are no blocks on their way, they will also be moved (and if the block being moved is a block of mucus, then the entities will be discarded), otherwise the head or block will pass through them; in the case of a block, entities can be smothered by the block if it is solid.

When the piston is turned off, the head will extend back. Moreover, if it is a sticky piston, then the head will try to move the block “glued” to it with it. The sticking effect only occurs when the head is moved, so falling blocks will still fall after moving if there is free space underneath them; also, a block that was moved by a sticky piston can be moved by another piston without any complications. In addition, if the sticky piston loses power before

Before he manages to
out
, the piston “unsticks” from the block, which remains in its new place.
If such a piston did not push anything out and the power is still turned off prematurely, then the block that was destined to be pulled along with it will be moved as usual (though somewhat faster).

Installing a piston on a Chinese lawn mower

The piston head, when installed, points in the direction of the player who installed it.

Installing the piston into the cylinder block

1. Before installing the piston into the cylinder, it is necessary to thoroughly wipe the crankshaft connecting rod journals and cylinder liners with a rag and rotate the crankshaft so that the journal of the inserted piston is in the bottom dead center (BDC) position.
2. Insert the liner into the lower head of the connecting rod so that the guide antenna on the liner fits exactly into the special groove on the connecting rod head.
3. Lubricate the liner with machine oil, place a special guide mandrel on the piston to compress the rings and lower the connecting rod into the cylinder. How to correctly install the piston into the cylinder in accordance with the signs is written above. If there is no guide mandrel, then squeeze each

   
   the ring will have to be done manually, gradually pushing the piston into the cylinder.

4. After the piston has entered the cylinder, carefully install the lower connecting rod head onto the crankshaft journal. We insert the liner into the bottom cover of the connecting rod so that the guide antenna on the liner fits exactly into the special groove on the connecting rod cover and lubricate the liner with machine oil.
5. Install the connecting rod lower end cap to the lower part of the crankshaft. At the ends of the lower connecting rod head and the cover there must be digital indications of the cylinder number.
6. Place the bottom cover of the connecting rod so that the cylinder numbers on the neck and cover are on the same side.
7. Secure the connecting rod cap with moderate force and install the safety pins on the bolts.

Preparatory moments

Before replacing the piston or rings (CPG in total), you need to get to the cylinder. For beginners who have no idea where this element is located, we will tell you. The muffler is just bolted to the cylinder. If you have no idea how to correctly install the piston on a 4t or 2t scooter, then first you need to remove the old CPG. The upcoming repairs can be divided into the following stages:

• Removing the scooter trim (plastic);
• Disconnecting electrical wires;
• Disconnect the oil hose;
• Engine dismantling;
• Removing the old piston, rings (CPG in total);
• Installation of new parts;
• Engine installation, wire connections and hose;
• Plastic fastener.

The plastic is folded to the side so as not to be crushed if careless. All bolts and screws are placed in a pile and, if necessary, sorted separately. After making sure that all hoses with gasoline and oil are disconnected, remove the engine. It is necessary to understand that engine removal differs depending on the design features of the scooter model. Once the engine is removed, you can begin to remove the plastic casing, which protects the CPG from external factors. Then remove the cylinder head. It is secured with 4 bolts. In order not to break the thread, all bolts are unscrewed crosswise.

We remove the cylinder and immediately inspect it. If there is no damage, then it can continue to be used. While the piston most likely cannot be used back.

Replacement cost

Here are approximate prices for replacing piston rings in services:

• domestically produced passenger cars - from 7-8 thousand rubles;
• Japanese foreign cars in sedan, hatchback, station wagon bodies - from 10 thousand rubles;
• jeeps, crossovers, minibuses - from 15 thousand rubles.

And the price for replacing a piston is usually high. This is explained by the fact that the procedure is included in the list of engine overhauls. Therefore, the cost is appropriate - from 20 to 40 thousand rubles.