How to Adjust Carburetor on Stihl Weed Eater

How to Adjust Carburetor on Stihl Weed Eater

Do weeds and grass have the run of your lawn or yard? Probably not if you own a Stihl Weed Eater.

Often called a grass trimmer, weed trimmer, weed wacker, or weed eater, this little piece of equipment will keep your lawn or yard looking great. One of the most well-known and popular brands on the market is the Stihl weed eater thanks to high-quality manufacturing, ease of operation, and the incredible durability of these power tools. With good maintenance, your Stihl weed eater will afford you great service for many years without requiring a replacement.

The Stihl Company works hard to correctly pre-set the various types of machinery and equipment that it manufactures. However, depending on where this equipment operates, environmental conditions that differ from place to place may affect how a piece of equipment idles, the speed of that idling, and even the power output of the machinery.

If your Stihl Weed Eater does not appear to perform correctly, you may need to adjust the settings of the machine’s carburetor. The Weed Eater features a two-cycle engine, so the adjustment of the carburetor is necessary every so often. Engines that require the use of an oil additive together with their gasoline fuel mixture occasionally may act up. But since the carburetor on the Weed Eater is small, it will only require a few minutes of your time to make the necessary adjustments.

Fine Tuning Your Weed Eater Carburetor to Your Needs

Necessary Tools and Process:

  • one small Phillips screwdriver

Step 1: Begin your carburetor adjustment by locating the screws for fuel adjustment. There will be two of these screws and you should be able to identify them on the carburetor’s side. One will have “Hi ” marking, while the other will have a “Lo” marking for identification. The “Hi” screw is for regulating your Weed Eater engine when it is performing at full throttle. The “Lo” screw will regulate the fuel use when your Weed Eater is idling.

Step 2:  Using your small Phillips screwdriver, you will need to tighten these screws in order to place the needle ends found on the screws, so that they enter into the carburetor’s jets.

Step 3: Now you can begin to adjust the positions of the screws. Locating the “hi” screw, proceed to turn it counterclockwise exactly one turn and a half. You will need to turn the “Lo” screw one complete turn in the counterclockwise direction. Now locate the Weed Eater choke and pull the cable out to start up your engine. The engine, at first, may sound rough when attempting to run, but you need to keep it running. This can easily be worked by using the gas throttle. In order to make a proper carburetor adjustment, the Weed Eater engine needs to be warm.

Step 4: With your Weed Eater engine running, begin to turn the “Lo” screw very slowly in the counterclockwise direction. You should continue turning until the Weed Eater engine idles smoothly. Your engine should not stall, nor should it die on you. At the same time, the engine speed should not be so fast as to rotate the Weed Eater’s head.

Step 5: Now push open the throttle fully and check your engine’s performance. If the engine begins to sputter, then you need to smooth it out. You can do this y turning the “Hi” screw a bit less than a quarter of a turn in the clockwise direction. Do this until the engine runs smoothly. Exactly how much you will need to adjust or turn this screw will depend on the size of its load, the Weed Eater’shead, and the freshness or staleness of the fuel in the Weed Eater fuel tank.

Step 6: You may now begin to operate your Weed Eater. You will want to keep the small screwdriver with you during operations, in case you need to make any further small adjustments to the carburetor.

FAQ on How to Adjust Carburetor on Stihl Weed Eater

Can I adjust the carburetor on my Stihl weed eater by myself?

Fresh from the factory, every Stihl weed eater has a standard-setting for the carburetor. The pre-set standard affords the best air-fuel mixture and functions well generally, in most environmental conditions. The adjustment possibilities for the idle speed of the engine will have very small limits and adjusting the carburetor will not always resolve problems with engine acceleration. Stihl provides any owners’ instruction manual with all of their weed eaters. Check the manual for the correct settings for your Stihl model of the weed eater.

My Stihl weed eater starts and runs fine at idle, but I can’t get it to run at full throttle.  Am I causing this by something I’m doing or is my weed eater in need of some repairs?

You need to appraise a few things. Is the fuel mix in your weed eater fresh? You should never use or store a fuel mix past two months either in the fuel tank or in a can. Then you can clean the screen in the Weed eater’s muffler, known as the “Spark Arrester” screen. Also, it may be necessary toinstall a new fuel tank’s filter, as well as cleaning or substituting the air filter. If your Weed eater still doesn’t run at full throttle take it to an authorized service center.

The Bottom Line

Even though these weed eaters have pre-set standard settings for optimum performance when they leave the factory, small adjustments may be necessary due to environmental conditions that differ from place to place.  You may find that how your weed eater idles, or its idling speed needs a slight adjustment to guarantee the best possible performance during lawn care maintenance.

With this easy six-step guide you will be able to adjust the settings of the machine’s carburetor. Remember that a two-cycle engine will occasionally require the adjustment of the carburetor. Fortunately, the Weed Eater’s carburetor will only require a few minutes of your time to make those small necessary adjustments. And these adjustments to the carburetor, together with proper maintenance, will, however, allow you the best performance from your Stihl weed eater.

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