Disassembling throttle grip Chinese STIHL 660 chainsaw
Didn’t pay much attention, because it was okay to work. But gradually the problem worsened, the rpm at a low throttle increased to the point that I could saw without even pushing the throttle lever. At some point the saw stalled and would not start at all. I was not particularly upset, because the farm had another saw, made by another company.
And the Chinese Husqvarna was gathering dust in a corner somewhere until it caught my eye again. And once again I wondered if it couldn’t be repaired? Naturally I could not even think about the service center, it was too far away, and in general I decided to look into it and understand myself. Searched on the internet, asked around on forums. The answer was pretty much the same everywhere: carburetor or crankshaft oil seals. Bought a carburetor, changed it. No result.
Well, about the seals, it’s a bit more complicated, but I wanted to take a look.
Started slowly disassembling. When I took off the cylinder I found a surprise. The gasket between the crankcase and cylinder was damaged.
Or rather, it was almost nonexistent. Only small pieces left of the gasket in the corners. As luck would have it, I didn’t have anything handy to make a new gasket.
I cut it out of cardboard, oiled it up and installed it. Reassembled saw, yanked starter. The saw started. A little adjustment of the carburetor, final assembly. and the saw worked for almost another year.
Then the same signs appeared again. chainsaws have the following components in addition to those mentioned above: carburettor air cleaning system, guide bar with saw chain, starter motor, chain tensioning mechanism, ignition, muffler, etc. Engine As already mentioned, the engine in modern chainsaws is a single-cylinder two-stroke carburetor engine about the structure and operation of the two-stroke engine, see here.
The illustration below shows it complete with the flywheel 1. clutch 2. ignition module 3. with a muffler 4 and a spacer sleeve 5 to install the carburetor. This imposes strict requirements with regard to the oil that is added to the fuel mixture. Chainsaws have a centrifugal clutch that engages automatically based on engine speed. Chainsaw centrifugal clutch At low speed the elements with friction pads 1. having degree of freedom in radial direction, are attracted to the center of the shaft by springs 2 and don’t transfer rotation to drum 3. Connected to the sprocket that drives the chain.
When the chainsaw engine speed reaches a value at which the centrifugal force exceeds the force of the springs, the friction segments press against the inner surface of the drum and begin to rotate it. This causes the drive sprocket to rotate and drives the saw chain.
As you can see in the photo, the sprocket is behind the clutch. In other chainsaws, the sprocket may be on the outside of the clutch. Sprocket on the outside of the clutch The main advantage of this type of clutch is that when the chain jams, the chainsaw clutch slips, without stopping the engine or causing damage to the mechanisms that transmit motion from the engine to the chain.
Ignition system Contact ignition, formerly used in devices equipped with gasoline engines, is a thing of the past. Chainsaws from the world’s leading manufacturers are equipped with contactless electronic ignition, which has spared users the cumbersome work of adjusting the contact gap and their frequent cleaning. Chainsaw ignition system The chainsaw’s electronic ignition system includes a flywheel 1 with built-in magnets, an ignition module 2 with electronic circuitry, a spark plug 3 and a high voltage wire 4.
Rotating flywheel with magnets induces in the module e. As a result, a spark flashes between the contacts of the latter and ignites the air-fuel mixture.
Pump and system malfunctions
As you know, nothing in this world is everlasting and eventually everything has to be repaired. The STIHL oil system in the STIHL Ls 180 is no exception and has its own specific faults. Let’s consider them in detail.
Signs of malfunction of the lubrication system, are as follows:
- Chainsaw chain is absolutely dry and shiny;
- the oil from the oil tank does not go out;
- the chain stretches quickly and this happens all the time;
- The guide bar moves sideways while sawing;
- the guide bar gets hot and in the area of the drive sprocket, melting of the paint is observed.
All of these signs, directly or indirectly indicate problems in the chain saw chain lubrication system.
The first thing to do after you suspect that the chain lubrication oil is not coming in is to check the oil supply. There are two ways to do this. The first way is described in detail in the instruction manual of the tool and is to start the chainsaw, increase the gas pressure to the maximum and direct it towards some obstacle.
If the lubrication system is good, oil will run off the bar tip and a strip of oil droplets will appear on the surface where the bar is pointing. If there are still irregularities in the system, the surface will remain clean.
The second way is to take the bar off the chainsaw and start it up. As the engine speed increases, oil will flow from the oil channel in the place where the bar shank is installed, if this does not happen, it is necessary to look for the cause of malfunction.
Begin by inspecting and checking the oil receiver (filter) on your STIHL 180 saw. As a rule, if the filter is heavily contaminated, the oil supply may stop.
To save money, you can try to clean a clogged filter, soaking it in gasoline.
Next, it is necessary to remove the sprocket drum, and check the condition of the drive pinion. The threads on it should be clearly marked, not nicked and have no other defects, also with the removed pinion, you should check the wire lever. It should crimp the pinion tightly and not rotate, otherwise the pinion stands in place and does not transmit power to the pump, and as a result, the oil supply stops.
If all of the above methods to find and eliminate faults have failed, it is necessary to apply extreme measures, i.e. е. disassemble the pump.
How to Remove the Pump
The oil pump is mounted on the right side of the base of the housing and the oil pipe from the chainsaw tank is connected to it at the same place. To remove the pump, you will first need to release the saw from the handle, to do this, unscrew the back handle of the unit and disconnect the throttle control rod. In the next step, it is necessary to take out the plugs of the handle shock absorbers and with the help of a strong slotted screwdriver, to squeeze them out of their places on the handle.
After the handle has been removed, the chainsaw body is turned upside down. The hose going from the oil tank to the pump will be visible at once. It must be removed from its seat.
Remove the pump with an M5 threaded bolt and a broad washer. Screw should be about 45-50 mm long. A washer is put on the screw and it is screwed into the pump (the inside of the pump is threaded). Further, as the screw is screwed in, the thrust of the washer will force the oil pump up the thread. This is how the pump is removed from its seat. Before you begin, we recommend reading an article on how to disassemble the STIHL 180.
For a better understanding of the pump removal process, you can watch the video below. In the video, the SC master shows in detail how to remove the oil pump from the chainsaw, and describes the main faults in the feed system.
The STIHL oil pump is a quality and robust piece of equipment, so it should only be replaced when all other system components have been tested.
After the pump is removed, it should be cleaned and blown out. As a rule, the main breakdown of the oil pump is its clogging. That’s why it’s best to replace the pump when it’s clogged.
Chainsaw clutch replacement. Recommendations and video reviews
Failure of chainsaw clutch is one of the most common failures of this equipment.
Over the question of how to remove the clutch on the chainsaw at home correctly and not to harm the tool, think not only inexperienced technicians, and experts who have more than once made its repair.
In cases where the gasoline cutters start to start badly, stall instead of starting check the clutch for malfunctions is mandatory, and recommendations regarding what will be presented next.
Owners of chain saws probably wondered more than once. how to change the clutch on a chainsaw? on most chainsaw models the disassembly and replacement of the clutch can be done manually by the owner, on few models unscrewing the drum can be done only in the workshop (such chainsaws are for example Husqvarna 137 or Partner 351).
In this review we will learn how to remove and change the clutch on a chainsaw yourself, when to do it and what tools you may need.
The chainsaw clutch drum is one of the most common consumables in a chainsaw, because it is the one that drives the cutting chain. The drums themselves are divided into two kinds. with a welded driving sprocket and with a removable ring, and in the second case only the removable ring wears out, the drum itself changes much less often.
Performing the repair of the chainsaw clutch, adhere to the rule. when the two chains are completely worn out, when the two chains are worn out, the clutch drum is replaced.
The level of wear of the sprocket can be determined without special devices, just inspect it. the chain, moving at high speeds, over time rubs the teeth on which it moves. If the wear is severe enough, replacement of the chainsaw clutch drum is inevitable.
In this article we will talk about Husqvarna chain saw 137. Replacing the clutch drum is an uncomplicated procedure and takes place in a few steps.
- First you have to remove the tire and chain brake cover. The combination wrench included with your chain saw is the right wrench for this.
- Then remove the air filter cover, unscrew the spark plug, stop the piston of the Husqvarna 137 chain saw. For this procedure we recommend to use a usual rope, because if you use a metal stopper there is a risk that the piston will be punctured.
- On the clutch disc itself you can see the direction to remove it and the two holes for the clutch puller.
- Unscrew the clutch clockwise and remove it. Under the clutch disc is a pressure washer, it must also be removed.
- Under the clutch drum itself is an oil pump with a washer, on which the new drum is installed.
- The chainsaw is reassembled in the reverse order except for tightening the clutch disk. After screwing on the clutch thread must be re-tighten the piston to avoid deformation of the starter group, which is on the other side of the crankshaft.
Chainsaw clutch drum replacement is an essential part of maintenance that will extend the life of all elements of the cutting equipment. After only a few seconds of use, a new chain on a worn reel will cause the chain to stretch.
In turn, this will result in a slight increase in chain pitch, increasing the load on the bearing and sprocket on the bar itself.
Therefore, having decided to save on timely service, then be prepared for the fact that after a short period of time it will require a much more serious investment for the purchase of all consumables of the cutting equipment.
Chainsaw chain. saw chain marking and beginner’s guide to sizing chains
When servicing clutches yourself, you need to know that:
- several saws have a washer, which is located both between the sprocket and the clutch, and the sprocket and the motor. Keep this in mind when carrying out repairs;
- The special spring for the oil pump drive must not be damaged during disassembly and must be returned to its original position. If not, the chain will not receive enough lubrication or will not lubricate at all.
A tool that has been repaired must be checked for tightness of bolt ties, chain lubrication, and motor operation (it must engage smoothly and run smoothly). Only then can it be operated.
Repair of chainsaw clutch with your own hands is carried out only in special protective clothing: mask and goggles.
The main faults, their causes and ways to fix them:
- If the chainring rotates constantly when the power train is unstable. It can be caused by a defective spring. In this case it is recommended to replace the damaged mechanism with a new one.
- Noise is heard during movement of the chain. This problem could be caused by an overheated cam or a broken spring. It is necessary to conduct an external inspection of the system and replace all worn elements.
- If the breakdown is due to the fact that the hitch often slips, you need to replace the mechanism completely.
In addition to the basic rules of operation described in the previous section, it is worth remembering about some nuances when replacing the clutch. Use only genuine manufacturer’s replacement parts. this is the guarantee of a long and productive life of the tool. The clutch is always threaded on the left side of every make of chainsaw. Before removing the clutch, carefully remove all dirt and dust from the tool so that it does not get.
How to remove the clutch?
The illustration shows a simple chainsaw model with the main parts and assemblies.
To disassemble the clutch, proceed according to the following plan:
- Remove the saw headset;
- Remove the chain and bar;
- Unscrew the air filter cover and carefully remove the spark plugs;
- Put the piston stopper in place;
- Use a puller to remove the clutch;
- Unscrew the clutch clockwise;
- Remove the drum and install a new one.
Reassemble in reverse order.
Removing the starter
In the next step, remove the upper cover housing and unscrew the 4 screws fastening the starter, then you must remove the oil tank and fuel tank cover. The starter is easy enough to remove and should be no problem.
After removing the starter motor, the interior of the chainsaw should be cleaned, because. к. There is usually a large amount of compressed fine sawdust on the housing under the starter.
Meaning and construction of the clutch
All latest generation chainsaws have a centrifugal clutch. The clutch transfers torque from the engine crankshaft to the saw unit. The element works exclusively in automatic mode, which prevents excessive stress on the engine. Main parts of the clutch:
- Drum. Can have a removable or non-removable sprocket; it is a transmission mechanism.
- Friction plates (counterweights). They move by centrifugal force, there is always a smooth connection to the drum part.
- Springs. They ensure a firm grip on the crankshaft.
After the chainsaw starts, the crankshaft is in motion. It has a clutch that makes the chain drive sprocket run away from it. Friction pads are clamped in idle mode so that no torque is transmitted to the drum. After the revolutions are increased, they move and drive the rotating sprocket.
Important! Professional models have a drum with fixed sprockets. This improves its durability, but it adds to the cost of repair.
How to disassemble a STIHL chain saw correctly
Before beginning with the STIHL saw disassembly, there is always a preparatory step. Have a comfortable table, dry rags, brushes to wipe parts gently, clean water, gloves and a dry place away from fire. It is also important to understand that there must not be any fuel in the machine. It is best to work it out rather than drain it and let the saw cool for a few hours before disassembling. The procedure is simple and straightforward:
- Remove the chain, bar and side cover;
- Clean your STIHL machine. using a compressor if you have one, brushes, dry sponge. to get rid of oil, dirt, dust, sludge and sawdust. Pay special attention to the drive sprocket. it may contain a lot of soot and dirt;
- If large accumulations of dirt are difficult to remove mechanically, clean gasoline can be used;
- find three rubber buffers and remove the crank. This can be done by removing the plugs. Using a screwdriver, first press out the upper shock absorber, and after it. the one at the rear handle;
- disassemble the back of the handle by unscrewing two screws. So we disconnect the rod from the gas trigger (it connects the carburetor and the gas trigger, which is in the handle);
- At the moment of fixation of the handle only on shock-absorber. we as if unscrew all “insides” of the saw and breaking aside. remove from the last fixer as if it were a rubber band;
- the starter is extracted by removing the upper cover and unscrewing 4 screws that fasten it. Next, we remove the tank caps. fuel and oil. Under the starter is often a buildup of dirt, sawdust, which also needs to be cleaned;
- A 13 head will help in unscrewing the flywheel. We block the crankshaft from turning by unscrewing the spark plug, namely through its hole we fix the piston stopper;
- on the fact that the piston is blocked. you can unscrew the flywheel nut;
- Before removing the clutch. disconnect the drive sprocket. The locking washer is removed from the grooves, also the needle bearing;
- Disassembling STIHL 180 chain saw involves removing the clutch with a 19-size head. Further remove reflective plate and oil pump actuator;
- disconnect the ignition cables and the air damper rod from the part called the engine lever, and remove the lever itself. Next, unscrew the nuts carb and air filter with a handy head to 8 with an extension cord (if available);
- unscrewing two nuts and pulling a little. you will remove the next part, the muffler;
- in the bottom of the saw there are 4 screws that hold the engine. Delicately taking it out, do not forget about a rubber pipe of the carburetor which can get in.
Disassembling the engine of the unit is a separate scheme, but in general, how to disassemble the chain saw STIHL. we reviewed. Regarding other popular models like 250. the procedure should be carried out similarly. Like all other parts you can always order a sharpening file for your chainsaw from KosiKasa.
How to unscrew the clutch on a STIHL chainsaw
How to unscrew the clutch on a STIHL chainsaw
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