How to change the sprocket on a STIHL 180 chain saw

How to remove the sprocket from a chainsaw and replace it with another (instructions with photos and video)

One of the most stressed parts of the machine, subject to the fastest wear and tear. The drive sprocket (pinion), located on the chainsaw clutch, transmits the rotation to the chain by hitting its links at high speed. Combined with the serious resistance of the material into which the blade “digs in”, the pinion takes on maximum pressure, which gradually grinds down the metal of the teeth.

As the sprocket wears down, it starts to play, resulting in very unpleasant consequences. Fortunately, this element belongs to the budget consumables, even for chainsaws of professional brands. How to determine the time to replace the sprocket, do it with your own hands and extend the service life for the new one, we tell and show in this article.

Design and principle of operation of the drive sprocket

Quality of tool maintenance depends largely on understanding of its components, so to complete the picture, let’s take a brief literacy on the types and features of existing transmission elements. The chain saw’s pinion, which is housed in the clutch plate and is set in motion as the engine speed increases. They can be of all-metal or split design. The first option involves complete replacement when worn, but in the case of the latter, it is sufficient to replace the removable ring gear.

The size of the sprocket wheel limits their application to all chain types. Two standards are common: with a pitch of 0.325 mm and 3/8 inch (the most important choice for replacement). This standardization is due to the power capabilities of the chainsaw engine. In addition to the sprocket pitch, you should choose based on the number of teeth (6 or 7) and the internal diameter of the bowl, but it is best to choose based on the specific model of tool you have.

Drive sprocket on chainsaw

Almost all modern chainsaws have a centrifugal clutch system. The specificity of this mechanism is that when the maximum number of revolutions of the gasoline engine is reached, the clutch drum starts automatically, transferring the rotation to the drive sprocket. This puts less strain on the tool’s main parts, extending the life of the tool and increasing productivity.

Star arrangement diagram

The clutch drum, where the sprocket is located, may be located on the inside or outside of the chainsaw body. There’s always a cover on top to protect the moving parts from dirt, sawdust, and dust. The clutch itself. is the metal disc in the clutch drum. The entire mechanism is attached to the engine crankshaft by bolts with springs, on the edges of which there are friction pads. When the engine rpm exceeds a certain value, centrifugal force is created, exerting a strong pressure on the inner side of the drum. After that, the sprocket is started. the chain saw starts to rotate.

READ Which chainsaw is the best for your home?

How to assemble?

The assembly of the clutch mechanism should be done in reverse order. First mount the sprocket to the needle bearing, then put on the drum, washer, gasket, and the clutch itself. Tighten counterclockwise, locking the piston slightly.

If your chainsaw has an oil-driven spring, it can be built into the drive sprocket. In most models, the correct location of this element is indicated by a special color or notch. To get to the right position, turn the sprocket until it clicks.

The last stage of assembly. install the guide rod. Release the handbrake during this process, and then check that the chain teeth are inserted into the appropriate grooves. After installation, set the chain saw chain to working condition. Finally remove the plug, screw in the spark plug and replace the filter. The final step in the repair is to fix the protective coating of the housing.

Types of drive sprockets

There are two kinds of drums, depending on the purpose of the chainsaw, professional and consumer. This will affect how often the sprocket is replaced: if you use a home saw much less often than a professional saw, you will have to replace parts like the sprocket, bearings or sprocket as less often as possible.

Drive sprockets are of two designs:

Solid or non-separable. As the name implies, this is a single piece of construction where the clutch plate and drive ring are permanently welded or pressed together. If necessary, the sprocket can be replaced as a whole.

On the left side of the clutch drum (aka sprocket) is a needle bearing.

There is a replacement sprocket on the right side of the clutch drum.

Once you have determined the type of saw and sprocket to be replaced, you can begin the process of updating the mechanism.

Design features of the drive sprockets

Every manufacturer specifies a tooth pitch in the instruction manual. Since the guide bar also has an idler sprocket (for tensioning), the sprocket pitch must be identical for both types of sprocket.

Chainsaw chain sprockets can be solid or assembled. In the first case, the sprocket includes a hub on which the toothed ring gear is pressed. This is how the parts in Champion chain saws are designed. It is best to change it completely, since it is almost impossible to maintain the factory set tension at home. It is also difficult to buy the sprocket individually.

On STIHL or Husqvarna chain saws, the replacement chainring is directly on the shaft of the drum, and is therefore easy to replace.

Tooth wear is determined by the following signs:

• There are clearly visible radii at the transition from tooth to socket.
• Tooth width is uneven in height.
• Metal chipping on the top of the tooth.
• On the inner surface of the bore in the hub, there are numerous scratches and risks (due to inadequate lubrication).
• There is a groove in the sprocket from the guide bar (the chain must also be replaced).
• The chain jams at the initial start.

If at least one of the above factors is present, the drive sprocket has to be replaced.

Before starting work (especially if the chain saw has not been in operation for long enough) it is worth checking the fastening of the guide bar. tightening screw is loose or fastening nuts are undone. the guide is out of alignment with the longitudinal line of the saw blade. It starts to contact not with the center, but with the periphery of the drive sprocket teeth and causes intensive wear. After tightening the above elements check the chainsaw operation: if the play is not eliminated, the sprocket has to be replaced.

How to remove the drive sprocket from a chainsaw?

As mentioned above, the sprocket can have a split or pressed crown. Therefore, the sequence of operations will be different.

For the stationary positioned crowning, the sequence is made sequentially:

• Disassembly of the guard;
• Removal of the guide bar together with the chain;
• Disconnecting the clutch from the engine (the piston must be secured beforehand);
• Removing the clutch with the drum;
• Remove the bevel from the drum with an ordinary open-jaw wrench (some brands include a puller in the scope of delivery).

Reassemble the assembly in reverse order. For some models, you will also have to remove the air filter before removing the crown.

When disassembling the chain saw chain sprocket with a removable ring gear, the procedure is much the same, but in the final step only the ring gear must be replaced.

Have the efficiency of the replacement checked after completing the work. To do this, check the chain tension: if, when the brake is released and you try to pull the chain in the direction of movement it is stationary, then the fastener is “overtightened”, and the tensioner should be slightly released.

If you have a special repair kit for your chain saw, it depends on whether this work can be carried out successfully. Otherwise you need to know the size and pitch of your chainsaw.

STIHL mc 180 chain saw. a concise overview of a reliable tool

Chainsaw STIHL mc 180 is a crosscutting machine. Changing the chain saw chainwheel sprocket. RemTehNet. Loading The VERMAHTA chain saw has been around for almost 70 years. The equipment belongs to the level of technology for domestic use. The model differs from professional tools in the material of working tools and is designed for occasional use, not more than 40 minutes per cycle.

Replacing the clutch

Do not use metal or plastic parts as stoppers when replacing the clutch. The former can scratch the cylinder and the latter can contaminate the cylinder.

• Activate the chain stop brake, remove the protective cover and remove the saw headset;
• Remove dirt, sawdust, dried grease, if any;
• Remove the air filter and the candle holder;
• Using a spark plug wrench, unscrew the spark plug;
• Rotate the crankshaft to bring the piston to its highest point and then withdraw it 6-9 mm;
• We use a 7-8 mm rope to stop the piston in its upper position;
• Use a special wrench to unscrew the nut on the clutch.

Most chain saw moving parts are right-handed. That’s why the nut on the clutch has a left-hand thread. To remove the cover turn the key clockwise. Do not do this operation with a hammer and chisel. you will break the edges!

• Remove the cover and drive sprocket. Diagnose malfunctions and assess component wear. Evaluate the condition of the needle bearing;
• If necessary, replace parts with new ones (the drive sprocket needs it most often);

To assemble the chainsaw clutch it is done in the reverse order, but you must pay attention to some peculiarities.

Nuances in the installation of the clutch system:

• On some chainsaw models there may be a washer between the drive sprocket and the clutch. Pay attention to which side it is facing the engine;
• Some oil pump drives are equipped with a special spring (or “whisker”) which is responsible for transferring the rotary motion from the drive sprocket to the oil pump. It is important to adjust the spring so that its free end (whisker) falls into a proper slot on the sprocket housing. If not, the saw headset will not lubricate;

Important: After the clutch has been disassembled and reassembled, be sure to check the automatic oil feed system.

Replacing the starter cord

Remove side cover. Inspect inside of safety guard. If there is no damage, check the starter unit. Unscrew the starter bolt and remove the spring. Diagnose the pulley with the cord. If the cord is intact, check each case of the starter mechanism:

The starter cord is made of synthetic material and will gradually wear out. If it is damaged, cracked or torn, it must be replaced.

When storing engines for long periods of time, it is important to avoid corrosion inside the cylinder-piston group. To prevent such undesirable processes, in addition to other operations, it is desirable to achieve a closed condition on the inlet and outlet valves. В.

Starter removal

In the next step, remove the top cover housing and unscrew the 4 screws holding the starter, then you must remove the oil tank lids and fuel tank. The starter motor is easy enough to remove and shouldn’t pose any problems.

After removing the starter motor, the interior of the chainsaw should be cleaned, t. к. there is usually a large amount of compressed fine sawdust on the housing under the starter.

Step-by-step instructions for replacing the chain saw chainwheel sprocket

To replace the sprocket on a chainsaw can be not only in the service, but also with their own hands. The whole process is relatively simple, to carry out the repair will need:

• spark plug wrench;
• wrench to remove the clutch (a normal lathe wrench for the nut will do, but it is desirable that it was thicker);
• piston stopper (special tool, but it can be replaced with a tight cord);
• An adjustable wrench/wrench (may not be useful).

Chain and sprocket replacement starts with fixing the piston in the chainsaw cylinder. To do this, remove the upper housing cover, the air filter, and unscrew the spark plug. A special piston stopper is installed in this hole, but it is not in great demand among craftsmen: a metal one can scratch the piston, and a plastic one can break and get inside. Most often, instead of it, take an ordinary thick cord or wire about 10. 15 cm long. It is important that there is no debris falling from it, or metal wires sticking out, all of which can get into the cylinder.

Put a stopper or cord in the hole. It is possible that the piston gets in the way and to get it down you must rotate the sprocket slightly by moving the chain or the chain itself clockwise.

Remove the cover on the side of the chain saw where the guide bar is attached. It is usually held in place by two bolts and clamped by two nuts. They can be unscrewed by hand or with a wrench or Allen wrench. The tensioning of the chain is loosened in order to remove it and the saw bar at once. At the same stage you should perform external cleaning of accumulated dust, sawdust.

Depending on the chainsaw design, the sprocket can be located under the clutch drum (either separately or as a part of it) or on top of the clutch. In the second case it is easier. remove the part and replace it with a new one.

Otherwise the assembly may need to be disassembled. The clutch with a left-hand thread, so unscrew it clockwise with a special or a grinder wrench, remove the drum, then you can remove the sprocket. If the chain saw has been in use for an extended period of time, parts can become very sticky. In this situation, you will need to use physical force, but it is forbidden to use a hammer or chisel. this will lead to the entire part becoming unusable.

Remove all parts:

Make an initial inspection of all components for wear and deformation. Then you can proceed to repair and take on the replacement of the sprocket on the chainsaw. If it is a part of the clutch drum. the whole part has to be replaced. It is important to choose a new part, which should be similar to the original one.

Gasoline chainsaw cylinder piston group

Construction of the BCG

So, what is the composition of the cylinder-piston group (CPG):

The cylinder, piston and cylinder group is the main part of the engine, faults of which inevitably lead to costly repairs. To keep it in working order, it is only necessary to follow the instructions clearly and observe some general rules:

• Use high-quality oils, diluted in the exact proportion that is specified by the manufacturer.
• Avoid overheating the engine.
• Follow the standards for the class of chainsaw (domestic, semi-professional, professional).
• Always use a chain that is properly sharpened and set in the right direction.

Malfunctions of chainsaw cylinder and piston groups:

All these and other not so common faults eventually lead to scoring on the cylinder or piston walls, which in turn leads to replacement of the whole cylinder-piston group.

How to diagnose what caused the scoring?

First remove the muffler and look in the window that appears and check the cylinder for scoring.

If the scoring is only on the muffler side, it is an indication that the chainsaw has overheated.

If the scratches are all over the cylinder and they are evenly spaced and have a lot of abrasion and a dark color, it is an evidence of an improperly prepared fuel mixture.

If scoring is like deep scratches, unevenly spaced, it is mechanical damage to the cylinder that occurs when you get a foreign body in the cylinder or chipped parts of the cylinder.

If the scoring is located in the ring area, it is a sign of a bad mixture quality. It is also possible that the saw is running in the Soviet manner.

Here are the main causes and types of problems with the cylinder head. If you have any questions, ask them in Комментарии и мнения владельцев or in VK group.

Here is a good video about diagnosing the cylinder head:

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Chainsaw starter cord replacement with your own hands

The STIHL 180 disassembly begins with the removal of the handle, which is attached to the body of the chain saw by 3 rubber buffers. To remove, it is necessary to remove plastic plugs from the inside cavity of the shock absorbers, then using a strong screwdriver, to squeeze first the upper shock absorber, later the one that is closer to the rear handle.

In the back of the handle is installed throttle trigger, which is connected to the carburetor through a wire rod, if you set to disconnect the rod from the throttle trigger, you need to unscrew two screws and disassemble the handle.

When the handle remains on one shock absorber, you need to unscrew the chainsaw body from the inside of the handle and, breaking it to the side, remove the body from the last rubber.

Handwheel chain saw STIHL 180 screwed with a huge effort, to remove it will need a head with an iron screwdriver. The nut holding the flywheel is unscrewed with a 13 head.

To block the crankshaft from turning, you must unscrew the plug and through the spark plug hole set the piston stopper, if not, use the old starter cord from the starter, with a knot tied to this address and immersed in a cylinder through the spark plug hole.

It is strictly forbidden to prevent the flywheel from turning by installing a power screwdriver or other tools between its ribs and the body, with this method of locking against rotation, the flywheel blades are not able to withstand the load and break.

How to Change a Chain on a Chainsaw

At the moment, there are a huge number of chain models on sale for chainsaws. First you need to know what size fits your chainsaw and do not make a mistake in buying. The second step is to install it correctly on the chainsaw. This is a somewhat time-consuming process, but if you know how to put on and adjust the chain to the saw bar without help from others, the conscientious owner should have no problems. We have tried to go through the whole process of putting the sawblade on the chain saw.

We hope after reading this article you will succeed the first time. But to minimize problems with the chainsaw and the chain in the future, don’t forget the 3 main rules:

• If the chain is worn and sagging, replace it with the newest one;
• If there is vibration when sawing and the cut is not good. watch the chain tension on the chainsaw;
• Never use defective or repaired by incomprehensible specialists saw blades, your health and the health of those who are nearby is more important than small savings on the purchase of a new and reliable chain.

How to Unravel?

When you remove the old chain or put a new chain on the guide bar, it can get tangled in the chainwheel. It can also be caused by sloppy transportation. When the chain is tangled, it curls up into rings.

Because of the insufficient flexibility in the transverse direction, the chain is very difficult to untangle with bare hands, because when you try to untangle one ring in the other place a new ring is formed.

You should put the chain on a horizontal surface and untwist the rings in different directions while pulling the bar in such a direction that the diameter of the rings would increase. Sooner or later the chain will unravel to its natural position.

There is another way to unbolt one chain link and straighten it out, then put it back together into a ring and rivet the riveted links back on.

Why does the chain come off??

Many chain saw users. even the most experienced ones. have had to deal with the problem of the chain jumping off the guide bar during cutting operation. The most common cause is insufficient tensioning or wear of the chain.

80% of the time, the stretched chain links slip out of the drive sprocket teeth and the chain fly off the guide bar due to the centrifugal force. Sometimes the problem is caused by the wrong position of the sprocket in relation to the pivot, or if the saw bar is not securely fastened to the chain saw.

Mainly the chain is stretched because of 3 main reasons: low-quality metal, excessive tensioning and use of low-quality oil. Also recommend to read about what oil to use for chainsaw chain, about STIHL and Husqvarna oils.

Saws and specifications

The STIHL mc 180 chain saw is in demand among hobbyists because of its convenience and reliability. The base model weighs only 3.9 kg. Sabre, the length of the blade 35 cm allows you to cut logs or drop trees up to 30 cm. Power of a 2L two-stroke engine. с., which allows you to do all household chores associated with cross cutting boards and even firewood in any kind of tree species. The fuel tank capacity is only 0.25 liters, but it lets you work non-stop for 45-55 minutes.

To use a mix of recommended or gear oil and unleaded AI-92 and AI-95 gasoline for refueling. 25 ml additive per liter of gasoline.

STIHL 180 chain saw chain is a continuous closed-circuit band with 50 links. Other features:

Operating mechanism, saw head, includes guide bar, sprocket and automatic lubrication system.

Chain tensioning system located on the side, which is convenient. Braking device for chain is included.

Depending on the length of the bar and the upgrading of the STIHL chainsaw MS 180 there are several modifications. Saws with the length of the saber 35 cm refer to the models, the marking of which includes 14, their length in inches. 14. The same configuration of the engine and its parameters, but with a bar length of 40 cm, called the MC 180 16. The STIHL mc 180 C-VE chain saw is a high-end tool. It has a 40 cm long guide bar, easy start system and quick chain tensioning system. Easy access to the air intake filter, a condition that prolongs tool life.