Starting a chainsaw Stihl MS 180 is a basic skill that is often difficult for beginners due to the nature of the two-stroke engine. An incorrect sequence of actions can lead to spark plug flooding or overheating of the piston group, so it is important to strictly follow the manufacturer’s instructions. In this article we will analyze not only the standard algorithm, but also the nuances of working with a cold and hot engine.
Many owners are faced with a situation where the tool simply does not start after winter storage or long-term inactivity. Most often, the problem lies in the lack of a spark, poor quality of the fuel mixture, or incorrect carburetor settings. Understanding the physical processes occurring inside carburetor and cylinder will help you quickly diagnose the problem.
We will look at common mistakes that users make when trying to pull the starter, and explain why ignoring the position throttle control lever leads to failure. Proper preparation of the workplace and the tool itself is 90% of success.
Preparing the fuel mixture and checking the system
Before you try to run Stihl 180, you need to make sure you have a high-quality fuel mixture. Two-stroke engines do not have a separate lubrication system, so the oil is mixed directly with gasoline. The proportion is usually 1:50 (20 ml of oil per 1 liter of gasoline), unless the oil manufacturer indicates otherwise.
Using old fuel that has been sitting in a canister for more than a month is strictly not recommended. Gasoline oxidizes, loses octane number, and light fractions evaporate, which makes starting extremely difficult. The mixture should be homogeneous, for which the canister must be thoroughly shaken before refueling.
It is important to check the condition fuel filter and air filter. A clogged air intake restricts the oxygen supply, enriching the mixture to the point where a spark cannot ignite the fuel. Remove the air filter cover and inspect the element for contamination.
⚠️ Attention: Never leave the saw with a full tank for long-term storage. Fuel can separate and tar deposits can clog carburetor jets, requiring complicated cleaning.
Cold engine starting algorithm
Starting a cold engine Stihl MS 180 requires precise adherence to the lever switching sequence. First you need to move the combination lever to its highest position - this is the mode Closed throttle/Start. In this position, the damper blocks the access of air, creating the necessary vacuum to suck in fuel.
After setting the lever to the start position, grasp the front handle with your left hand and press the saw to the ground. With your right foot, step on the rear handle stop. Make 3-5 sharp jerks with the starter until a characteristic “pop” appears or the first attempt to start. This is a signal that the cylinder is filled with the fuel mixture.
☑️ Checklist before the first push
As soon as the engine seizes, immediately move the combination lever to the middle position - Open Throttle/Run. Now one jerk is enough for the saw to reach operating speed. If you release the throttle immediately after starting, the engine may stall, so on some models you need to lightly press the throttle trigger to enter idle mode.
Starting a hot engine and restarting
The situation with a hot engine is radically different from starting a cold one. If Stihl 180 warmed up and you have just finished work or are taking a break, the algorithm is simplified. The throttle control lever is immediately set to the middle position (Work).
During a hot start, there is no need to use the closed choke mode, since the fuel in the carburetor is already in a vapor state and is ready to ignite. Excessive enrichment of the mixture in this case will only “flood” the candle. 1-2 jerks with the starter are enough for a confident start.
If the engine has overheated (for example, after running for a long time under load), it may take time to cool down. In this case, you can remove the spark plug, blow out the cylinder and let the tool stand for 10-15 minutes. Overheating reduces compression and can lead to scoring if you try to load a hot saw.
If the saw does not start with a hot engine, try unscrewing the spark plug, drying it and blowing out the cylinder with several pulls of the starter without a spark plug.
Diagnosing startup problems
When standard procedures do not help, it is necessary to move on to diagnosis. The most common reason for failure is lack of spark. Unscrew the spark plug, put a cap on it and press the threaded part to the metal of the cylinder (or muffler). Pull the starter sharply and see if there is a blue-white spark.
If there is no spark, the problem may be in the spark plug itself (breakdown, carbon deposits), in the ignition coil (magneto) or in the wire circuit. It is also worth checking the spark plug gap, which for Stihl 180 should be 0.5 mm. An incorrect gap disrupts the sparking process.
The second important aspect is compression. There should be resistance when pulling the starter. If the starter handle is pulled out too easily, without any characteristic compression, it means that the piston group is worn out or the rings are stuck. In this case, the saw will not work.
| Symptom | Probable Cause | Elimination method |
|---|---|---|
| No spark, spark plug is dry | No fuel supply | Check filter, channels, carburetor |
| There is a spark, the spark plug is wet | Filling the spark plug with fuel | Dry the spark plug, blow out the cylinder |
| There is a spark, but it won't start | The seal is broken | Check seals, gaskets, crankcase |
| Weak compression | CPG wear | Replacing the piston group |
Adjusting the carburetor and mixture quality
Carburetor Stihl MS 180 often does not have adjusting screws for the quantity and quality of the mixture (L and H), being equipped only with an idle speed screw. This is done to simplify operation and protect against unauthorized intervention. However, if the saw stalls when adding gas or runs erratically, it may need cleaning.
If your model has adjustment screws, remember that the factory settings are optimal. Screw L is responsible for low speeds and transient modes, and the screw H - for maximum power. Mindless twisting of the screw H can cause the engine to run lean, which causes overheating and scuffing.
⚠️ Attention: Adjustment of screw H (maximum speed) should only be done using a tachometer. Exceeding the permissible speed (about 13,500 rpm for MS 180) is guaranteed to damage the engine.
Often the problem is solved by simply cleaning the carburetor jets and channels from tarry deposits of old fuel. To do this, the unit is removed, disassembled and washed with a special carburetor cleaner or ultrasound.
Why does the saw stall when the throttle is opened?
This is a classic sign of a lean mixture during transient conditions. Most likely, the low speed jet is clogged or the tightness of the intake tract is broken, and the engine “chokes” when the damper is opened sharply.
Ignition and exhaust system maintenance
A chainsaw muffler is not just a pipe for exhausting gases, but an important element of the system that affects traction. There is a spark arrestor inside, which becomes clogged with carbon deposits over time. If the saw has lost power and stopped developing speed, check the condition of the muffler.
Carbon deposits can be burned off with an open fire (observing safety precautions) or removed mechanically. It is also worth inspecting the place where the exhaust gases exit the cylinder - a coke plug may also form there, preventing normal gas exchange.
The spark plug should be regularly cleaned of carbon deposits with a wire brush and the gap checked. If the electrodes are burnt out or the insulator is cracked, the spark plug must be replaced. For Stihl 180 NGK BPMR7A spark plugs or analogues are often used.
Typical errors during operation
One of the main mistakes is starting the saw by hand, without fixing it. This is not only inconvenient, but also dangerous, since if the starter jams, you can get injured. Always place the saw on the ground by stepping on the rear handle.
Another mistake is ignoring the sounds of a running engine. If you hear a ringing or squeaking noise, this may indicate detonation or bearing problems. Operating the tool with extraneous noise leads to rapid destruction of the components.
Keeping the air filter clean and using a fresh fuel mixture solves 90% of problems with starting a chainsaw.
Don't forget to lubricate the chain. Although it does not directly affect engine starting, running without chain lubrication will overload the engine and cause rapid tire wear. Make sure that the oil flows evenly along the entire length of the tire.
Why does the saw start and immediately stall?
Most often this occurs due to a clogged fuel filter in the tank or poor ventilation of the fuel tank. Check to see if the hole in the tank cap is clogged. The reason may also be air leaks through the crankshaft seals.
Is it possible to use AI-92 gasoline instead of AI-95?
For engines Stihl It is recommended to use gasoline with an octane number of at least 90-92. The use of AI-95 is acceptable, but not critical. The main thing is the freshness of the fuel and the absence of alcohol additives (ethanol), which destroy rubber seals.
How often should the fuel filter be changed?
It is recommended to change the fuel filter at least once a year or whenever the carburetor is seriously cleaned. If the filter turns black or sticky, it must be replaced as it creates resistance to fuel flow.