There are multiple variants of Stihl chainsaws. Some are intended for woodwork and others are used professionally. Professional saw or not, almost all the models have similar problems.
So, how to resolve Stihl MS 250, MS 261, MS 271, MS 291 problems?
Lack of proper airflow and fuel mix causes most of the problems. However, sometimes, it can be a simple spark plug problem. Stihl MS 250 and 261 suffer from it. On the contrary, Stihl 271 and 291 often have carburetors and bearing problems. Lastly, don’t hesitate to hire a specialist if these seem too bothersome for you!
However, this was only a sneak peek of a full detailed discussion. Stay with us if you want to know everything about your Stihl chainsaw!
- 1 Stihl Chainsaws: Most Common Problems & Solutions
- 2.1 1. Bad Airflow Ruins Engine Efficiency ( Stihl MS 250, MS 261, MS 271 & MS 291)
- 2.2 2. Faulty Fuel Supply Degrades The Engine ( Stihl MS 250, MS 261, MS 271 & MS 291 )
- 2.3 3. Faulty Spark Plugs Fail to Ignite ( Stihl MS 250, MS 261, MS 271 & MS 291 )
- 2.4 4. Clogged Carburetor Blocks Gas Passage ( Stihl MS 271 & Stihl MS 291 )
- 3 Frequently Asked Questions
- 4 Final Words
Stihl Chainsaws: Most Common Problems & Solutions
Stihl chainsaws are one of the most used and trusted chainsaws. However, they aren’t always perfect and thus create different problems once in a while.
To save you some time, we have categorized the problems and solutions.
1. Bad Airflow Ruins Engine Efficiency ( Stihl MS 250, MS 261, MS 271 & MS 291)
An engine requires good airflow to burn fuel. An air filter keeps the dirt away from entering the engine.
However, they get dirty from time to time. A dirty air filter ruins the combustion process. As a result, the engine might emit smoke or face problems on start-up.
Replace the Air Filter
The engine breathes air to burn fuel. Therefore, a blockade caused by an air filter can ruin combustion.
Check on the air filter and if it’s clogged, your best bet is to replace it.
Don’t worry, though. They are very cheap and easy to install. There are two screws; one at the upper side and the other at the bottom side.
Just unscrew to get the dirty one out and install a new one.
2. Faulty Fuel Supply Degrades The Engine ( Stihl MS 250, MS 261, MS 271 & MS 291 )
A poor fuel supply causes your engine to run rich or lean. Both conditions can wear out your engine and must be avoided.
Check On the Fuel Supply
First, you’d like to make sure your engine is running on the proper fuel mix. Also, if your saw has been unused for some time, it’s best to remove it completely.
Here’s a good mix of 2 stroke fuel –
- For a 50:1 ratio, 1 gallon of gasoline needs 2.6 fluid oz of oil
- For a 50:1 ratio, 1 Liter of gasoline needs 20 ml of oil
Also, you can use a fuel system cleaner to get rid of any dirt or gunk. Pour the fuel tank and let it work for a couple of hours. Then start the engine to distribute the cleaner evenly.
There’s also a fuel line connected to the fuel tank. Pull the fuel line out just a little bit and see if it’s damaged or not. If so, it must be replaced.
3. Faulty Spark Plugs Fail to Ignite ( Stihl MS 250, MS 261, MS 271 & MS 291 )
Spark plugs are the most crucial component in the spark system. It plays an important role in ignition.
All four of these chainsaws suffer from this problem. It’s because spark plugs get worn out due to constant usage.
However, Stihl MS 250 and Stihl MS 261 tend to have more spark plug issues. On the contrary, users of Stihl MS 271 and 291 have suffered less.
As a manufacturer, Stihl recommends changing spark plugs every 100 hours of service.
Check and Replace the Spark Plugs
As we’ve already mentioned, spark plugs get worn out. This creates a gap between electrodes. So, we’ve to check the gap and other dirt issues first before replacing them.
To help you out, we’ve simplified the process for you –
- First, locate the spark plugs. It’s usually at the back of the engine. If you have the engine manual, you can easily get the information from it.
- Remove the spark plug and check whether it has dirt or carbon build-up. If it has some build-up, it must be sanded with 180-220 grit sandpaper. Also, if the spark has oil build-up or dirt, use a wired brush first.
- Don’t plug in the spark plug yet. Only attach the spark plug wire. Now touch the metal plug head with a metal surface and pull the cord.
- If you’re seeing sparks, your spark system is fine. However, if the engine is still having difficulties starting up, follow us to the next step.
- Now we’re going to check the gaps. A spark plug needs to maintain a certain gap to create ignition. Too much gap means the electrodes fail to spark efficiently. On the other hand, a lesser gap means not enough air to incite an ignition.
- The gap gets enlarged over time due to spark plugs being worn out. If the gap seems too big, it’s time to replace the spark plugs.
Also, here’s some recommendation from us regarding spark plugs –
This will help you pick whatever you like and get your engine started!
Replacing a new spark plug is very affordable. However, if your engine is still suffering, let’s go to the next step.
4. Clogged Carburetor Blocks Gas Passage ( Stihl MS 271 & Stihl MS 291 )
A carburetor makes sure your engine is getting enough gas to burn. It mixes air with fuel and helps the engine run on mixed gasoline.
Among all Stihl lovers, users of MS 271 and 291 have complained the most about having a bad carburetor.
MS 271 and MS 291 are two heavy-duty chainsaws used for professional work. Thus they require more gas flow and due to more usage, carburetors cause various problems.
However, users of MS 250 and MS 261 aren’t immune to this problem at all.
Step-1: Clean the Carburetor
To ensure continuous gas flow, we can’t allow any clogs or dirt to be inside the carburetor. Thus we have to remove and clean it as soon as possible.
Here’s how you clean and adjust the carburetor –
- Remove the air filter holder from the carburetor with the help of a walled socket. If your air filter is jammed and can’t be cleaned, consider replacing it.
However, this procedure is focused on the carburetor which occurs often for 271 and 291 users.
- Unfasten the choke and throttle linkage respectively. Be sure to remember this order. The spring side of the carburetor is the choke linkage.
- Now carefully detach the carburetor and get ready to dismantle the carburetor. Also from now on, it’s a good idea to take pictures of each step so that you can keep everything in order.
- First, look for dirt and build-up and remove them from outer parts with a brush.
- There are 4 screws on top and 1 big screw at the bottom. Unscrew the top 4 first and detach the cap. Check for dirt and other build-ups underneath the cap and clean them.
- Now unscrew the bottom screw and remove the cap. You may notice several small holes filled with dirt or grimes. Get a small pick and clean the holes. If these holes are clogged, this is the main reason behind your saw not starting.
- Now assemble all the parts respectively. If you have taken pictures, just do the procedure in reverse.
This process should fix the carburetor problem. However, you’re not done yet. We still have to tune the model properly.
Step-2: Tune the Carburetor Properly
After you’ve reattached the air filter back, ensure the gas tank is half-filled. Now you can balance the carburetor screws and find the best position.
Identify the Carburetor Screws
There are 3 screws in a carburetor. The high (H), low (L), and the idle (T). Usually, these letters are written on the screw or beside the hole.
Before adjusting, we should know what roles they play in a carburetor. This will give you an overall idea of what you need to fix –
- H screw: The H screw controls the fuel/air mix when the engine is running at a high RPM.
- L screw: The L screw controls the fuel/air mix when the engine is running at low RPM.
- T screw: This T screw regulates the overall fuel flow when the engine is idle.
With everything explained, it’s time to start tuning!
Adjust the H, L & T Screws
Get the engine running and let it warm up. This takes approximately 30 seconds if you rev it 3-4 times.
- First, we’re going to focus on the L screw. Slowly turn the L screw clockwise till the engine stops running.
- Now, turn the L screw counterclockwise till you hear the engine idling smoothly. Now, try revving the engine and look for a smooth rev up. Keep adjusting it until you get the result.
- With the L screw fully adjusted, it’s time to mess with the T screw. Turn the T screw clockwise until you see the chain moving!
- The moment you see the chain moving, turn it counterclockwise and do it until the chain stops. We’re determining the exact position of the screw, so be slow and precise. The engine must run smoothly while idling.
- With the L and T screw out of the way, it’s time to fix the H screw. Turn the screw counterclockwise till the engine starts making rough noises.
- Now all that’s left is to find the precise location of the H screw. Start turning the H screw clockwise till you hear smooth noises. Keep adjusting until you get it right!
- Press the trigger and check whether the engine is emitting smoke or not. If the engine is accelerating without emitting any smoke, it means tuning is complete.
And that’s all you’ve to do to fix the carburetor. This was a huge procedure so don’t forget to congratulate yourself.
One major symptom of a bad carburetor is when it dies during high RPM. It might also start bogging down. In this case, you will need your carburetor replaced.
These are some of the best carburetors of our choice. Don’t worry, though. They are all compatible with Stihl chainsaw models –
Hopefully, these will help you get started right away!
If all these steps didn’t fix your engine, it’s likely to be the bearing. Also, installing a bearing is tough for average people and requires finesse and dexterity.
So, in such cases, getting professional help is the best idea. If these methods seem too bothersome or hard, don’t hesitate to hire a specialist.
Frequently Asked Questions
Question: What does MS mean on Stihl chainsaws?
Answer: The MS in Stihl chainsaws stands for Motorsäge. It means chainsaw in german.
Question: Is Stihl 271 a pro saw?
Answer: Stihl MS 271 is the balance between professional and homeowner saws. They are heavy in general but can be easily operated in both types of tasks.
Question: Is the MS 291 a good saw?
Answer: Stihl MS 291 is a heavy-duty saw. It can cut through almost anything with ease. This is also more beginner-friendly than the Husqvarna 455 Rancher.
Now, you can do everything by yourself to fix Stihl MS 250, MS 261, MS 271, MS 291 problems. Hopefully, you now know how to solve these problems.
So, did these solutions help you fix your saw? Tell us using the comment section.
Finally, best of luck!