How to Adjust a Chainsaw Carburetor: A Step-by-Step Guide

Adjusting the carburetor of a chainsaw is an important part of keeping it running properly. So, what is a chainsaw carburetor? A carburetor is a piece of equipment that mixes air and fuel to make a mixture that can be lit.

If the ratio of air to fuel is off, your chainsaw won’t be as efficient, or it may even fail to start. As carburetor adjustment is an important part of regular chainsaw maintenance,

To tune your chainsaw carburetor properly, you’ll need to adjust the carburetor’s three adjustment screws.

This post will walk you through the steps necessary to make sure your chainsaw is running at an optimal level.

To change my carburetor adjustment, what tools will I need?

To adjust the chainsaw carburetor, you will need a few tools. These include a screwdriver, an adjustable wrench, gasoline line pliers, and a tachometer to measure the revolutions per minute (RPMs). We recommend the Hipa Pack-of-12 Carburetor adjustment tools for carburetor tuning.

Step 1: Run the Saw Idle for Few Minutes

How to Adjust a Chainsaw Carburetor

The first step in adjusting the carburetor on a chainsaw is to run it at idle for a few minutes. This will allow the engine to warm up. Let the saw sit idle for 30 seconds and hold it upside down (handle upward, bar downward, facing the ground). If the saw keeps running, go to the next step; otherwise, repeat the screwing process.

Step 2: Adjust The Idle Screw

How to Adjust a Chainsaw Carburetor

The first step is to adjust the idle screw. To ensure optimal performance, adjust the idle-speed screw instead of the low-speed screw. To do this, turn the idle screw clockwise until the chain just starts to move.

Step 2: Adjust The Low-Speed Adjustment Screw

How to Adjust a Chainsaw Carburetor

The next step is to adjust the low-speed screw.

To do this, locate the low-speed screw. You can easily find low-speed screws with your chainsaw’s letter L. The low-speed screw is close to the engine and far from the air filter on your chainsaw.

Then, start screwing it clockwise and anti-clockwise to find the right setting for your saw. As you turn the low-speed screw, the RPMs will start to drop. Be careful not to turn it in too far, as this will cause the RPMs to drop.

Step 3: Adjust the High-Speed Adjustment Screw

How to Adjust a Chainsaw Carburetor

The next step is to adjust the high-speed adjustment screw. This screw is easily identified by the letter H on your chainsaw.

The purpose of the high-speed screw is to adjust the high-speed RPMs when the trigger is pressed. When you throttle the trigger, screw the high-speed screw clockwise to increase the RPM.

On the other hand, if you turn the screw in an anti-clockwise direction, the RPM will decrease. Turn it counterclockwise and clockwise until the RPM starts to drop. Find the spot where it’s idling at the highest RPMs.

Now, start turning the high-speed screw counterclockwise very slowly until you hear the RPMs begin to come back down. Leave it in this setting, where you will have it the majority of the time. With this setting, your chainsaw can idle all day while still producing excellent triggers.

Two Stroke and Four Stroke Engines

There are two types of engines used in chainsaws: two-stroke and four-stroke. The two-stroke engines require a mixture of gasoline and oil to run the saw. Whereas, in a four-stroke engine, you will not need to mix oil and gas.

Carburetor Adjustment Benefits

Once you have adjusted the carburetor on your chainsaw, you will notice several benefits.

Save Fuel Expenditure

With a properly adjusted carburetor, you will save on fuel expenditure as the engine will be running at optimal performance.

Smooth Running

A properly adjusted carburetor also ensures that your chainsaw runs smoothly.


A properly adjusted carburetor will ensure the performance of your chainsaw is optimized. It leads to better cutting power and improved efficiency.

Steve’s Small Engine Saloon

How to Tune a Chainsaw FAQs

What do the L and H mean on a chainsaw?

The letter of the screw represents high (H), low (L), and idle (I). The L represents the low-speed screw, the H represents the high-speed screw, and the I represents the idle screw.

What are some common problems that can occur if the carburetor on my chainsaw is not adjusted correctly?

If the carburetor on your chainsaw is not adjusted correctly, it can lead to a variety of problems. These include:

  • The engine speeds up and slows down. Regularly
  • Engine Lacks Power at High Speed
  • Engine Over Speeds
  • Excessive Idle Speed

Bottom Line

Adjusting the carburetor on a chainsaw is not difficult and can make all the difference in the chainsaw’s performance and efficiency.

If you follow the steps outlined above and adjust the carburetor settings correctly, you’ll be able to enjoy an optimally-running chainsaw in no time.

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Charlie Bass

Charlie has been a mechanic for over 25 years and has worked on everything from small engine gardening equipment to huge diesel-electric mining haul trucks, trains and even aircraft. This broad range of industry experience gives him a unique insight into almost anything mechanical especially with an engine, including gardening and landscaping equipment. He currently owns his own mobile mechanic business and lives with his family in Australia.

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