How To Clean Your ATV Carbs

Cleaning your ATV Carburetor is a fairly easy job. If it is your first time performing this maintenance just take it slow, step-by-step, and you will get through it in no time at all. Obviously, the carbs are not going to be identical on every ATV. However, by following these instructions you should have a good basis with which to start your service.
 
If your ATV is one with a twin carbureted engine, you will have to do this process twice. It is very important to avoid mixing the parts between the two carbs, as each carb will have a slightly different construction that might not be easily identifiable to the naked eye. The best way is to do one at a time.

Let's Get Started
To keep from having to clean up any gas spills or making a mess on the driveway or garage floor, slide a piece of cardboard under your ATV before you remove the carburetor.
 
First, you will need to turn the fuel switch to the off position. Then you will need to locate the float bowl drain screw on the bottom of the carburetor and drain the fuel. You will generally find this screw at the bottom of the float bowl. It can be accessed by a screwdriver.

Depending on your ATV model, you may need to remove the seat and the left and ride side plastic pieces to allow yourself better access to the carb. You can also remove the air intake and airbox if you need even more room.

To save time when you are putting everything back together, I highly suggest that you mark each hose and wire with a number and write down where the number corresponds to on the carb. Even if you think you will remember exactly where everything goes, you will save yourself a lot of hassle if you do this before removing any hoses from the carburetor. I don't know how many times I have been interrupted while working on my ATV and when I finally get back to it, which has been days before, I cannot remember where anything goes.

Next, you will want to free the carb from the assembly. On most ATV models you will need to remove the air and fuel lines along with two large hose clamps that connect the airbox to carb and carb to engine intake. Some ATV models will also have electrical connections that need to be unplugged. Access to the throttle linkage may require removal of a black plastic cover on the carburetor and one screw. Again, mark and write down where everything goes.

Basic Carb Service
If you are only interested in doing a basic carb service, you may be able to remove the float bowl without removing the carburetor from the ATV. This how-to step will start at the float bowl.

A rough idle and other problems can be caused by a float bowl that is filled with gasoline residue, rust and other small particles. If the ATV has been sitting for extended periods of time, fuel can dry up and form a thick goop in the float bowl. This will invade the jets and cause all sorts of issues with the fuel/air mixture.

Locate the float bowl on the bottom of the carb and remove the four screws that hold the bowl to the carburetor with a tight-fitting screwdriver. If you have trouble breaking the screws loose, spray them with WD-40 or Liquid Wrench and let it sit for at least 30 minutes to avoid stripping the screws. The screw heads are generally fairly soft on carbs and are susceptible to stripping.

Once you have removed the bowl, inspect the gasket for any wear or tears. The gasket should protrude above the rim of the bowl. If it doesnít, it should be replaced. If you plan on soaking the carburetor in cleaner overnight, make sure that you remove the main jet and main jet holder, slow jet, float and corresponding seat washer, fuel needle and fuel needle seat.

If you removed the jets, it is a good idea to take the time to inspect them for clogs and clean them. To clean them, soak the jets in carb cleaner. After you have let them soak, grab a toothbrush and clean the jets allowing the soft bristles to enter the tiny holes throughout the jets. It is important to use only a soft bristle brush. A wire brush or anything similar can actually widen the holes and you will accidentally re-jet your ATVís carb.

If the carbís float bowl has a build up of residue and other particles, you will want to soak it in the gallon can before cleaning. Depending on the amount of build up, it may take a lengthy soaking period to break up all the goop and dissolve it. Some ATV models have float bowls with hard to reach crevices. If yours is like this, you can use compressed air to help blow out any of the gunk that is left lingering in the bowl.

Advanced Carb Cleaning
If you plan on a complete cleaning, continue with these advanced Carb Cleaning steps.
 
After you have cleaned the float bowl, remove the diaphram and metering assembly. To do this, locate the circular cap retained by four screws at the top of the carb. Remove the screws and carefully lift off the cap so as to not allow the spring underneath to shoot out uncontrollably.

You should now be able to carefully remove the diaphram and metering assembly. Remove the metering needle by using a screwdriver or nut driver to turn the plastic retainer and free the needle. Inspect the diaphram for wear or tears. Please be extra careful with the diaphragm as this is one of the most expensive carburetor components.
 
Before you put the diaphram down on your work bench, invert it so that it looks like a mushroom. This will prevent the diaphram from taking any unnecessary abuse while it is outside of the carb. To clean the diaphragm assembly, spray cleaner on a shop rag and wipe off any varnish. Do not spray the cleaner directly on the diaphragm itself as it is made from rubber and the abrasive cleaner can destroy it.

Some ATV models also come with a primer. These can usually be removed by backing out two screws. Make sure that the O-ring seal isnít damaged. The orifice directly inside the carburetor from the primer can have a significant amount of residue and goop. Cleaning the primer is an important step because the priming action pushes residue through the carburetor network and can really impact your performance.

Next, you will want to remove the choke assembly and idle adjustment assembly. These are both fairly easy to remove. To disassemble, remove the screw at the top of the plastic tube for each assembly. Once the screw is backed out, the tube can be pulled off the actuating shaft. The most difficult task is removing the choke plunger. The easiest way is to remove it by lifting up while rotating the retaining fork.

It is now time to call upon that ounce or two of technical skill you have. Removing the throttle shaft assembly can be a nerve-racking task, and many skip this step because removing the throttle plate can be difficult. If you plan on soaking the carburetor body in cleaner, I recommend removing the throttle plate and shaft.

You can remove the plate by backing out the two Phillips screws that hold it in place. This is the most important step. The screws are staked, meaning the tips of the screws were widened so they keep a tight fit to the shaft. If you canít find a tight-fitting screwdriver, avoid this step so you donít strip out the screws and use a spray cleaner as opposed to soaking. Before removing the plate, make sure you note the side facing out as this side must be facing out when you re-install it. If you do remove the plate, the shaft on most carbs can be pulled out by removing a C-clip on the top of the shaft and then carefully removing the felt seal with a slotted screwdriver. While removing the shaft, make sure to write down where all the springs and linkages go.

The carburetor body is now ready to be soaked in cleaner. After the carb has been in the cleaner for about a half hour, the residue and particles should easily break free with compressed air, a rag and a toothbrush. You can also use Q-tips to reach smaller crevices. Then use a spray cleaner to hit all the orifices and crevices in the carb which will remove any lingering particles.

Now that the cleaning is complete, itís time to reverse the process and install all the components back onto the carburetor body. It is important that you donít overtighten critical components like jets and the metering needle.

When you are finished, you should have a more powerful engine that is easier to start and more responsive. You may even be surprised at the increase in power. You probably have forgotten the power your ATV had because it is lost so gradually.

Tools And Supplies To Have On Hand
You will not need many tools or supplies for a carburetor service, but there are a few key things you should have on hand before starting the job.

1. You will, of course, need carb cleaner. It is not a good idea to buy a generic or an unknown brand. Ask around and find a cleaner that will do a good job of breaking down and dissolving built-up residue quickly. I have had success with Gunk and B-12 Chemtool. You will need a spray carburetor cleaner and a gallon can to soak parts in overnight if you plan on doing an in-depth cleaning. The gallon can will usually come with a metal bin that will allow you to suspend parts in, as sediment will break up and fall to the bottom of the can. If you have access to a parts cleaner, even better.

2. A soft bristle toothbrush. This is a helpful tool when you are cleaning the jets and scrubbing interior portions of the carb.

3. Several small plastic bins or cups to help you keep important parts separated. Paper or styrofoam cups are great because you can write which part is inside right on the cup.

4. Compressed air. A can of compressed air, like ones used to clean a computer keyboard, will work if you do not have access to an electric air compressor.

5. Shop rags. Carburetor cleaner is an abrasive chemical, so you will need to have a few rags on hand for any spills or oversprays that might come in contact with vital rubber components.

6. Paint marker, scratch paper and a pencil to mark parts and write down where they go on the carburetor.

7. New, upgraded Jets. If you are considering re-jetting due to altitude or adding a performance exhaust system, while you have them out for cleaning is a perfect time to replace them.
 
I hope these instructions have helped you "do-it-yourself". If you would like complete instructions on how to clean the carburetors of your specific ATV, pick up the ATV Service Manual for your model.

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