How to set the throttle link on the STIHL 180

STIHL 180 ms chain saw

Germany. country of assembly and production of all original STIHL chainsaws ms 180. Fakes are easy to spot when they are underpriced. Chinese or Polish copy of STIHL MS 180 will cost two or three times cheaper than the original, while the quality of construction of such saws, of course, differs from the German. There may also be a lighter and cheaper plastic.

Original STIHL MS 180 chain saw retails for about 4,5-5 thousand UAH. The original product is always sold with a data sheet. The serial number of the tool and the motor series are indicated in the data sheet.

The STIHL ms 180 chain saw comes with:

  • The chainsaw in a half assembled state;
  • fuel tank;
  • chain, sprocket, tire;
  • chain brake;
  • handle;
  • passport;
  • instructions for use of the product.

The manual also indicates the types of lubricant suitable for the STIHL ms 180 chain saw. As additional accessories, the manufacturer offers to purchase:

  • oil filling system;
  • Fuel filling system which makes it safe to fill up;
  • Test, sawing templates;
  • holder, with which the owner can sharpen the chain links with his own hands.
throttle, link, stihl

MS-180 chain saw component diagram

To adjust the STIHL 180 carburetor

Usually, special screws are responsible for the quantity and quality of fuel supplied to the diffuser, and by adjusting them you change the fuel channel cross section. But this STIHL 180 chain saw has no LD screw on the carburettor for easy carburettor maintenance.

The valves are designed so that the optimum quantity of fuel reaches the nozzle at all engine speeds. And for adjustment here is responsible the screw LD, by turning which air flow to the idle stroke nozzle is regulated. How the engine speed changes.

To adjust the carburetor on a STIHL 180 chain saw you will need a normal flat-blade screwdriver and an electronic tachometer (optional). The adjustment algorithm is as follows:

throttle, link, stihl
  • Check the air filter. Replace the filter element if necessary.
  • Screw in the LD screw counterclockwise all the way and then unscrew it two turns. Attention, the thread is left! There is a screwdriver hole on the body of the saw to access the screw. Start the engine and warm it up for 5-7 minutes.
  • Turn the LD screw slowly clockwise to adjust the idle speed. There are 2 possible situations: The engine RPM is very low when idling. Engine won’t idle. Turn the LD screw until the saw starts to turn and then turn it 1/2 turn back (the chain should stop).
  • The saw spins in idle speed. In this case, slowly turn the screw counterclockwise until the chain stops, then turn it another 1/2 turn in the same direction.
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If after all the manipulation of the carburetor settings, the chain continues to spin at idle, the saw should be taken to the dealer service center.

The video below shows a detailed adjustment of the carburetor of a STIHL chainsaw 180 with an electronic tachometer.

How the STIHL 180 works: design, principle of operation

The main components of the carburetor on the STIHL 180 chain saw are

  • Fuel pump (with internal diaphragm);
  • main (diaphragm) chamber;
  • diffuser;
  • throttle valve and air valve;
  • needle valve;
  • fuel injectors;
  • nozzle with valve;
  • Idle speed adjustment screw.

Operating principle is as follows. The carburetor is connected to the fuel pump in the carburetor by a special channel. Intermittent piston stroke creates vacuum in the crankcase. That lifts the diaphragm in the fuel pump and opens the valve to let the fuel flow into the carburetor.

Fuel then flows through the filter element (screen) and through a special channel into the main chamber. There is a control diaphragm in this chamber which controls the fuel by pushing on the rocker arm which in turn lowers the needle valve.

For the raising of control membrane is responsible the rarefaction, appearing in the carburetor diffuser due to the turn of air, throttle flap. As soon as the engine is running, it is necessary to lean the mixture. We lower the choke, the vacuum in the diaphragm is minimal and the diaphragm goes back to its place.

Fuel went from the main chamber to the nozzle with a check valve or nozzles at idle (when throttle closed). There it mixes with the intake air and the ready mixture enters the engine cylinder. Check valve prevents air from diffuser to the main chamber.

Disassembling the throttle grip on a STIHL 660 Chinese chainsaw

Didn’t pay much attention to it as it was fine to operate. But gradually the problem worsened, rpm at a low throttle increased to the point where I could saw without even pulling on the throttle lever. At some point the saw stalled and did not start at all. I was not upset, because I had another saw from another company.

And the Chinese Husqvarna was sitting quietly in a corner somewhere, until one more time it caught my eye. And once again I wondered if it could not be repaired? No thoughts of a service center, of course, very far away, and in general I decided to look into it and figure it out myself. Searched on the internet, asked around on the forums. The answer was almost the same everywhere: the carburetor or the crankshaft seals. Bought a carburetor, changed it. The result was nothing.

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Well, about the seals, it’s a little more complicated, but still decided to take a look.

Started disassembling it little by little. When I removed the cylinder, I found a surprise. The gasket between the crankcase and cylinder was damaged.

Or rather, it was almost nonexistent. The gasket was just a little bit of it in the corners. As luck would have it, there was nothing on hand to make a new gasket.

I cut it out of cardboard, oiled it and installed it. Reassembled the saw, yanked the starter. Saw started. Little adjustment of carburetor, final assembly. and saw was working for almost another year.

Then the same symptoms appeared again. Construction of chainsaws In addition to the components listed above, chainsaws are equipped with a carburetor air cleaning system, a bar with a saw chain, starter motor, chain tensioning mechanism, ignition, muffler, etc. Engine As already mentioned, modern chainsaws use a single-cylinder, two-stroke carburetor engine as the engine, see the structure and operation of the two-stroke engine here.

The diagram below shows it complete with the flywheel 1. clutch 2. Ignition module 3. muffler 4 and spacer bushing 5 for installing the carburetor. This imposes stringent requirements on the oil added to the fuel mixture. The chainsaws have a centrifugal clutch that engages automatically based on engine speed. Chainsaw centrifugal clutch At low RPM, elements with friction pads 1. have degrees of freedom in the radial direction and are attracted to the center of the shaft by springs 2 and do not transfer the rotation to the reel 3. connected to the sprocket that drives the chain.

When the chainsaw engine speed reaches a value at which the centrifugal force exceeds the spring force, the friction segments engage with the inner drum surface and start to rotate it. As a result, the drive sprocket starts to rotate, driving 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 stalling the engine and without causing damage to the mechanisms that transmit motion from the engine to the chain.

Ignition system Contact ignition, previously 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 gap in the contacts and their frequent cleaning. Chainsaw ignition system Electronic chainsaw ignition consists of handwheel 1 with integrated magnets, ignition module 2 with electronic circuitry, spark plug 3 and high voltage wire 4.

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The rotating flywheel with magnets induces in the module e. As a result, a spark flashes between the contacts of the latter, igniting the air-fuel mixture.

Stihl MS170 MS180 Install Carb & Linkages

throttle, link, stihl

When flushing the carburetor is useless

Cleaning the carburetor with your own hands is the easiest way to restore the performance of the device. However, it is far from always able to fix various types of breakdowns. To make sure that the device really needs to be cleaned, and washing will help restore the functionality of the mechanism, you need to disassemble it.

If after disassembly some factors are found in the form of corrosion deposits (oxidation of aluminum), as well as the formation of warping in the carburetor channels, the usual washing will not help here. You can use the procedure of washing in a special ultrasonic bath, but even in this case, the chances of restoring performance do not exceed 50%-60%.

Drawing a conclusion, it should be noted that the need and possibility of cleaning the carburetor can be assessed only after it is disassembled. Here it should be noted at once that the carburetor cleaning procedure can be performed in two ways:

  • Automatic. washing is carried out in a special ultrasonic bath. Peculiarities of the procedure are considered below
  • Manual. this method is not always suitable, and it is a cleaning of the mechanism channels with a special carburetor cleaner. This method is only suitable in cases where there is no deformation of the carburetor channels. If in the channels began the process of corrosion or warping, then there, depending on the complexity of the process, can only help wash in an ultrasonic bath, but not always

Buying an ultrasonic bath specifically to wash the carburetor chainsaw, just not rational. That’s why in this material we will consider the procedure of manual cleaning. What is cleaning with an ultrasonic bath, you can also find out from this material.

This is interesting!Ordinary blowing the carburetor compressor will not do anything, so do not comfort yourself with the thought that now blow the channels, and chain saw will work like new.

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