Stihl Chainsaw Carburetor Adjustment (The 360 Guidelines)

Carburetor adjustment in chainsaws can become a headache, especially for new users. It’s not always easy to find that sweet spot where the chainsaw thrives. Besides, adjusting the carburetor wrongly can also be dangerous. 

There are three adjustment screws that allow you to adjust the carburetor using a screwdriver. The screws are labeled LA, L, and H. 

It’s important to go through the adjustment procedure so that you can get the most out of your chainsaw. So, let’s get to it. 

Stihl Chainsaw Carburetor Adjustment: Step-By-Step Procedure

The first thing to keep in mind is that you should keep the air filter, bar, and chain on during the procedure. Because it requires listening to the sound of your chainsaw while adjusting the carburetor, keeping them on will have an impact on the adjustment. 

If you have a Poulan chainsaw, check carburetor adjustment Poulan chainsaw. For now, let’s get to the process of adjusting your Stihl chainsaw carburetor.

Step 1: Locate the Adjustment Screws

You have to find the adjustment screws on your chainsaws. Take a look at the picture below. You can also use the user manual of your chainsaw to identify the screws. 

stihl chainsaw carburetor adjustment screws

Before starting to adjust the carburetor, you need to run the chainsaw on idle for about a minute. This is for warming up the engine before getting to the procedure. 

Step 2: Turn the Idle Screw

Locate the idle screw on your chainsaw. It will be labeled as LA. Insert the screwdriver inside the idle screw hole and slowly turn it clockwise until the chain starts to move. 

Step 3: Adjust the Lowest Speed Screw (L)

Take the screw out from idle and switch to the lowest speed screw. It should be labeled as L. However, sometimes, the screw may not be labeled. If it’s not, it’s the one that’s closest to the engine and furthest from the air filter. 

You can turn the lowest speed screw clockwise and anticlockwise. Here’s where it gets a bit tricky. You will have to listen to the engine sound to determine where to place the screw. 

When you turn the screw clockwise, the RPM will increase. At one point, the RPM will start decreasing. In simpler words, the engine will get louder and then less loud. 

The same goes for when you turn the screw anticlockwise. It will keep getting louder, and at one point, the RPM will start decreasing. So, you have to keep the screw where the RPM is the highest. Turn the screw anticlockwise and stop when the RPM just starts to stop. 

Step 4: Turn Back the Idle Screw

Come back to the idle screw and turn it anticlockwise slowly until the chain stops moving. So, now you’re done adjusting the idle screw and the lowest-speed screw. 

Step 5: The Highest-Speed Screw (H)

Adjusting the highest speed screw is not recommended for your chainsaw. So, the best thing is to leave it as it is. However, if you’ve already adjusted it before, there can be two things you can do.

First of all, use a tachometer to read the RPM and make sure it’s within the safe limit. The second thing is to trust the limiter cap on the screw.  

 If you are interested in a visual demonstration of the procedure, Steve’s Small Engine Saloon has an excellent video on it.

Why Adjust Stihl Chainsaw Carburetor?

An improperly adjusted carburetor can result in a few issues. For instance, when you press the trigger, the chainsaw is supposed to start immediately.

Also, when you keep the chainsaw down for a rest, it should go back from idle mode back to its speed without any lags. 

Improper adjustments of the carburetor will cause issues with these optimized settings. So, you have to make sure that the chainsaw is working correctly by adjusting the carburetor.

Some Things to Remember

When adjusting your chainsaw carburetor, there are a few things you need to remember. Let’s go through them briefly. 

Limiter Cap

Each screw will come with a limiter cap so that you don’t go too high or too low with your screw adjustment. This is an in-built setting from the manufacturer. However, the limiter caps can also cause problems in optimizing your chainsaw. 

For instance, when you’re adjusting the lowest speed screw, if you don’t hear the engine going loud and then less loud, it can be due to the limiter cap. The limiter cap may not be giving you enough freedom. 

In such cases, you can take the limiter cap off. How you can take the limiter cap off may vary depending on the chainsaw model you own. The image below shows a removed limiter cap from a Stihl chainsaw.

removed limiter cap from a Stihl chainsaw

Highest Speed Screw Adjustment

The most dangerous screw to adjust on your chainsaw is the highest-speed screw. If you cross the recommended RPM level, it can prove to be dangerous.

The more you increase the RPM while adjusting the chainsaw, the faster the chain will spin. Without limiting the speed, it can put a strain on the engine, damaging it as a result. 

So, it’s better to leave the screw as it was. However, just to be safe, get a tachometer if you do decide to adjust the high-speed screw. You can also trust the limiter cap placed on the screw by the manufacturer. 

Safety Measures

When working with your chainsaw, you have to ensure safety. There are two things to keep in mind in this regard. First of all, don’t do the process indoors.

Work in a well-ventilated area, preferably outdoors. Even when working indoors, make sure all windows and doors are open. 

The second thing is to use earmuffs. Even though adjusting the carburetor requires listening to the engine sound, it’s still mandatory to use earmuffs.

They won’t hinder the procedure. Chainsaws can be very loud, and you need to protect your ears from damage. 

Stihl Carburetor Adjustment Tool

If your Stihl chainsaw doesn’t have limiter caps, you will need a special screwdriver to adjust the screws.

Another important tool that comes to mind when adjusting the chainsaw carburetor is a tachometer to keep the RPM level within the safe limit. 

In case you don’t have these tools, you can consider getting the following options:

Product Features
HUZTL Carburetor Carb Adjustment Screwdriver Compatible with most 2-cycle engines.

2-teeth splined.

Y15 iron with nickel plating.

Runleader Digital Tachometer Accurate RPM reader.

Replaceable battery.

Easy to use.

Frequently Asked Questions

What are the 3 screws on a Stihl carburetor?

The carburetor screws of your chainsaws are high-speed adjustment screws, low-speed adjustment screws, and idle adjustment screws. They are labeled as H, L, and LA, respectively. 

Why does my Stihl chainsaw bog down as I give it gas?

There can be several reasons behind this issue. The spark plug or the carburetor might be dirty, the carburetor may not be adjusted properly. Or, maybe you are using the chainsaw at the wrong altitude. 

What do the limiter caps do?

The limiter caps are there to ensure that you don’t turn the screws too much in any way. However, if they’re hindering you from setting the carburetor at an optimized position, you can remove them. The process may vary depending on the model you own. 

Wrap Up

Learning Stihl chainsaw carburetor adjustment is a part of operating the tool to the best of its potential.

Besides, improper adjustment can not only prove to be inefficient but also dangerous for the user. So, it’s essential to keep the carburetor screws in their proper places. 

Once you’re thorough with the process, you will be able to feel the difference when using the chainsaw. It will be more effective than before and comfortable to use too.

Jim Boslice

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