How to Put a Piston Properly on a Chainsaw

All my attempts to find out what kind of model it is and in what years it was produced have ended. to no avail (I will be VERY grateful if you will help me in any way in this matter). However, I can tentatively assume that this is somewhere in the 60-70s of the last century. On the chainsaw is used CONTACT ignition from the company BOSCH.

The number. 21554 is knocked out on the crankcase. What kind of number is this is a mystery to me.

There is a nameplate on the left side of the saw.

What kind of information is indicated on it for me also. a dark forest :-))).

I partially dismantled the chainsaw (for cleaning and assessing the condition of parts). I also replaced the tip of the spark plug (it was all cracked) and installed the ignition switch (it was absent at the time of purchase of the saw). These details, as you know, are not original :-))). And one more minus is that there is no oil tank cap. (Everything is indicated by arrows in the photo).

Carburetor air damper drive.

There is a chain on the saw. TAKASAGO (I have never heard of such ones, but the inscription on the cutting tooth testifies to this).

The length of the tire is 620 mm.

Chainsaw DOLMAR. About three or four months ago, this instance was in my hands chainsaws Dolmar.

Dismantling. assembly of the STIHL MS180 chainsaw. The degree of compliance with the request: 21.43%
Fragments of the text of the post. Dismantling. assembly chainsaws STIHL MS180. Disassembly chainsaws STIHL MS180. Assembly chainsaws STIHL MS180.

Chainsaw PARTNER 352.

Replacing the piston group in a chainsaw or trimmer

Repair at this level should always be balanced. In such small engines operating at high revs, replacing one piston that is burnt or stuck does not give a long result and, if necessary, the entire piston group must be changed. Therefore, you need to consider whether to use this saw further or to purchase a new saw.

If this is a professional model, then such repairs should be carried out, but if it is an old household model such as Husqvarna 40 and it has worked for more than ten or twelve years, it is not profitable to repair it. Because its repair will cost, so much as the purchase of a new saw, let not Husqvarna, but on PARTNER P350XT CHROME, worth 165 is definitely enough. over, the company Husqvarna sells such saws, because PARTNER is its subsidiary.

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But if you still decide to repair a chainsaw or trimmer, then you need original spare parts that are not cheap. With proper operation of the engine, 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 is jammed, 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 resource of 500-600 hours, Husqvarna 340/350. 1000-1200 hours, professional chainsaws at least 2000-2500 hours, subject to strict observance of the operating instructions. In fact, it is impossible to rely on these figures, since the real resource can significantly differ both up and down. But it can be roughly said 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 after working its hours, it completely pays for itself, and it’s another thing that for example this saw was refueled with one gasoline, without oil, and it got stuck. Such a saw has to be repaired, since all other parts are normal.

Video: How to Put a Piston Properly on a Chainsaw


Many companies specifically overcharge the cost of spare parts to buy new models. For chainsaws and trimmers, for example, the company Stihl, spare parts are available in a larger assortment than on the Husqvarna. Therefore, choosing a particular model, find out how things are with spare parts.
PBT

How to install rings on the piston of a push-pull scooter

Posted on 08/25 | Author: scooter.rv.ua

In installing rings on the piston of a two-stroke scooter, however, as well as a four-stroke, there is nothing complicated, and many know this. But most scooters who only recently acquired a similar technique do not even have an idea about how to replace the piston on the scooter, how to correctly install the rings on the piston, where the arrow on the piston should look, and much more. In this lesson, I will tell you how to properly put the rings on the piston and assemble the piston into place. Since we already talked about four-stroke engines before, we will only talk about two-stroke engines. So, our piston has worn out and needs to be replaced.

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First of all, the rings and piston wear out, and usually you only need to change them. With severe piston wear, it is necessary to bore the cylinder. It also opens up when the piston wedges in the cylinder, forming deep scratches on the walls of the latter. There is nothing wrong with this, and if your new cylinder has passed the correct bore (for which you will need to lay out only about 10), it will need a repair kit of rings with a new piston. Such rings are marked with a 0.25 mark. The second bore, respectively, 0.5, etc. up to one.

After buying a piston, you need to assemble it. In the kit, as a rule, you will find the piston itself, two compression rings, a third thin corrugated ring (about its purpose later), a piston pin and two piston pin retaining rings.

Now about the third ring in the kit. Its purpose is to spring-tighten the lower compression ring. It installs under it itself, and usually does not bear any benefit during operation. You can throw out this ring, or you can put, there is no difference. Many piston manufacturers do not have it at all.

How to Put a Piston Properly on a Chainsaw

It’s time to put everything in place. Depending on the scooter model, the 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 top is thinner than the bottom and has a different cross section.

It is necessary to pay attention to this when installing, the upper one is thinner and sharpened at an angle.

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Also pay attention to the inscription on the ring (usually the letter T or the repair size), the inscription should always be on top, that is, the opposite of the finger. First you need to wear the bottom, then the top. You do not need to stretch and bend them. These manipulations must be carried out carefully.

In the grooves for the rings there are locks that prevent the rings from turning during operation, so the gap of the rings should be in these locks, otherwise you will not stick the piston into the cylinder.

And the last important point is the arrow (1) at the bottom of the piston or the inscription EX. And 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 flap valve. If you put the locks in the direction of the exhaust, the piston will not last long, the rings will be pulled into the exhaust window and gradually grind it off.

For all the manipulations with the piston, it is necessary to put a rag in the crankcase window so that inadvertently something doesn’t get there, we still need a crankshaft with bearings.

When installing the piston pin, pay attention to the condition of the cage (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 it would be inconvenient for you to insert a finger and a second snap ring). Then put the finger with the bearing and the second snap ring, when locked in the groove it will give a definite click.

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

If you have any questions during the piston replacement process, you can ask them in the comments box or on the forum of our site. Good luck in the repair.