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How Do You Adjust a Carburetor on a Kohler Engine?

The carburetor on a Kohler engine is a device for supplying a spark-ignition engine with air and fuel mixture. Its primary function is to transfer the energy in the compressed air and fuel mixture to the piston in order to create power.

The carburetor’s components are a storage chamber for liquid fuel, a choke, an idling valve, an accelerator pump, and an idle-stop valve. A well-tuned carburetor will be steerable and will provide you with a proper cutting experience. 

As a lawnmower owner, you should always do things so the system runs well. They lie at the heart of an engine’s combustion process, and there are a number of adjustments that need to be made if you want your engine to run smoothly. 

Lawn mower in action in a lawn
Lawn mower in a lawn

You’ll have to make the adjustments needed to the carburetor and we’re here to help you with this issue.

Why should you adjust a carburetor?

Carburetors are used in almost all engines. They help to regulate the air entering the engine and, by adjusting idle running conditions, they can ensure that the mower is running smoothly and doesn’t do any harm to it. 

Lawn mower carburetor
Lawn mower carburetor

There are several adjustments that can be made to get your car running at an appropriate speed at idle. There are plenty of reasons why you should adjust your carburetor. 

The first one is that it will help your engine last longer. Another one is that it makes your mower more fuel efficient by reducing pollution created by using too much fuel or not enough fuel. 

High-quality carburetor tuning can make your vehicle run better than ever before. As soon as you start driving, your engine will produce more power and more heat which means that you need more fuel and less air. 

This means that you must increase your engine’s airflow while driving in order to avoid turbulence and reduce pollution. Carburetors are fitted with an idle mixture screw which is used to adjust the air-fuel mixture at idle.

The fuel-air mixture varies according to the throttle position, so it is important for a user of the carburetor to match the right amount of fuel with the right amount of air at idle.

Carburetors are designed to provide an excellent baseline for further tuning, so that you can compare your before and after tuning results with the engine system you have in mind. 

And once you get that baseline, you can make adjustments to improve performance with something other than adjusting fuel pressure or opening up the throttle plate.

Here’s how to adjust a carburetor on a Kohler engine

Here are the steps you can proceed to make adjustments to your Kohler engine.

Remove the air cleaner and filter assembly

You need to take it off of your engine to remove the air cleaner and filter assembly.

Locate the ideal mixture and idle speed screws

Before starting the process, you should know the location of idle mixture and idle speed screws in the system which typically sit on top of the carburetor on your Kohler engine.

Try checking with your vacuum gauge

If you have a vacuum gauge, then it’s optional to connect your vacuum gauge to a manifold vacuum port before you start the engine. If not, an engine won’t idle properly and be adversely affected by rough idle issues.

Time to warm up

Now it’s time to warm up the engine. Before starting the engine, make sure that you are doing so on a hard, flat surface (preferably your driveway). Turning it over in an open area can help take off any dirt buildup.

Make sure that the throttle is on “Medium” and let it run for 5 minutes to allow it to reach operating temperature.

Adjust the idle speed screw

You need to adjust your speed setting on the carburetor. Be sure that you adjust the idle speed of your engine after reverting it to “factory” spec. You’ll need to do this during warm up if the idle speed is too high.

Set the throttle to slow mode

Set the throttle to “Slow” mode, set the tachometer to engine, and connect the lead from the tachometer to the spark plug wire.

Locate black limiter cap

Locate the carburetor on the right side of the engine. Near it you’ll see a black limiter cap. On top of it is an idle screw that controls the speed at which your engine can run.

Adjust the desired mixture

Now, you have even more control over the engine. You can adjust the mixture by turning each screw in the opposite direction or individually by 1/8 turns to reach your own ideal rpm setting. Tightening the limiter cap clockwise will decrease the rpm, and loosening it counterclockwise will increase it.

Make sure to note each adjustments

After making a few adjustments, give the engine some time to “refine” the adjustments. If you feel it still isn’t right, reverse the settings by going in the opposite direction of where you would have been.

To make sure you have reached your desired settings, that engine speed is smooth and vacuum levels are on point, continue making small adjustments.


A bad carburetor can slow down your mower or may cause it to turn and die. So, it is important to do a thorough check of the carburetor of your Kohler engine. This will not only save you gas, but it can also help your car get up to speed more quickly.

Some other quick methods for tuning include setting the throttle according to what RPM range it’s located within and adjusting speeds via optional products such as manual shifting devices.

Kohler engines have carburetors that need adjustment. Our Kohler engine carburetor adjustment guide will help you adjust the carburetor so your engine will run smoothly. If you need additional support, please contact a professional mechanic for help.

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