The carburetor is the most common problem area in all small engines. The carburetor is where the fuel mixes with the air to be burnt. Carburetors are on almost all types of combustion engines. When an engine sits for a long period of time without being ran, the fuel will start to break down. Make sure you replace the fuel in your tank before you start your engine after cleaning the carburetor otherwise you will just recreate your troubles.
The carburetor being cleaned in this is off an old motorcycle and will look like most other carbs off a motorcycle or ATV. While most carburetors won't look the exact same as the one being shown, they still will have most the same functions and layout.
Needle nose pliers
Wrenches or socket set
Carb and choke cleaner
Carburetor and parts cleaner (optional)
Gasket set or carb rebuild kit (recommended)
Step 1: Remove the Carburetor
Picture 1: The first step in taking off the carburetor is turning the fuel valve off on the fuel tank. Track the fuel line down to the carb and remove the hose. (If the line is old and cracked you will want to replace the hose to ensure there are no leaks.) There will also be an overflow hose coming out of the carburetor, remove this hose too. Next, loosen the screws in the clamps in the front and rear of the carb. The carburetor should be loose; you should be able to wiggle and twist the carb to remove it. The carb will be held in by the throttle cable. The throttle comes off by twisting the top cap. When you unscrew it and it comes off the slide will still be attached to it. The carb should now be removed.
Picture 2: After removing the carb, you need to remove the throttle slide from the cable(still attached to the vehicle). This can be a tough task but the picture shows it completed to show the parts. After you have the cable unhooked you can pull everything off the cable, and should have the parts in the picture.
Step 2: Remove the Float
Picture 1: The float is the bottom part of carburetor and is the first thing taken apart when cleaning the carb. To remove the float bowl, unscrew the four screws on the bottom of the carburetor. Remove these screws with care because they strip very easily. The float bowl then can be pulled off the carb. If you are not replacing the gasket be sure to not tear it. Cleaning the parts will be addressed later so don't start cleaning yet.
Picture 2: Remove the float pin by pulling it out with a pair of needle nose pliers. After the pin is removed, the float can be removed. In some carburetors, the needle will be hanging on float and will come out with it. In this carburetor it is not this way so some steps will be out of order.
Step 3: Remove the Jets
Picture 1: This step will differ from carb to carb, but the jets will need to be removed. In this carb there are some splash plates that needed to be taken off, not all carbs will have these. Jets are screws that have a hole through the center of them which the fuel flows through to mix with air. The plates need to be removed to get to the jets. The main jet is short and fat; will have a hex head or a flat screwdriver head. The pilot jet is long and skinny which will take a flat head screwdriver to remove. The jets can be seen in picture 2.
Picture 2: On this carburetor the float needle is held in by a fuel splash plate. Remove this plate so the float needle can be taken out to be cleaned.
Step 4: Remove Outer Parts
Picture 1: The last step before cleaning the carb is removing the last parts from the outside. The air screw and the idle screw can be removed with a flat head screwdriver. They are located on the sides of the carb. The idle screw is the larger screw which adjusts the idle when the engine is idling.
Picture 2: Remove the air screw. The air screw is the smaller screw which adjusts the air flow through the carb when the engine is running.
Picture 3: If the choke can be removed from the carburetor, remove it. Turn the top with a wrench and the choke like slide out.
Step 5: Clean Parts
Picture 1: BEFORE CLEANING CARB AND PARTS REMOVE ALL GASKETS AND O-RINGS. The easiest way to clean the carburetor and the parts is to soak them in a gallon of carb and parts cleaner, however the can is pretty expensive for just one use. Follow the instructions on the can for cleaning. Parts can also be cleaned by spraying carb and choke cleaner.
Picture 2: Be sure so wear safety glasses, gloves are recommended, for cleaning. Parts should be scrubbed with a wire brush and then sprayed with carb and choke cleaner. Spray the cleaner into the holes that the jets, air and idle screws, float needle, and choke came from. When cleaning the jets, be sure to spray cleaner into the holes. To make sure the jets are clean, look through them into light to make sure the hole is cleaned. If jets are not completely clean, blowing compressed air through the hole will remove left over debris.
Picture 3: Make sure all debris is removed from the carburetor. Dry the carburetor and all parts, the easiest way is with compressed air. Blow compressed air into all holes, and blow off all parts of the carb. After everything is dry, install the new o-rings and gaskets back into carb if you have them, if not, reuse the old.
Step 6: Install Jets
Install the parts in the opposite order in which they were removed. In this case, the float needle and the fuel splash plate were installed first. The jets and the splash plates were installed next.
Step 7: Install Outer Parts and Float
Picture 1: Install the outer parts of the carburetor first. Start with the choke, then the air screw and idle screw. When installing the air screw(the skinny screw), screw it in all the way then back the screw out a turn and a half. This is the baseline, after the engine is running you can adjust it so the engine idles properly. The idle screw should be screwed in just enough to hold it. The baseline adjustment will be in a later step. Next install the float. To install the float, line the holes up with the holes in the carburetor and slide the float pin in. The pin will slide around freely, just make sure it is centered so it is secure. To make sure the float needle is working properly, move the float up and down to make sure the needle moves freely. If the needle gets stuck in the up position it needs replaced.
Picture 2: Install the float bowl onto the carb with the 4 screws on the bottom. The carb should now be complete, without the throttle.
Step 8: Install the Carburetor
Picture 1: Install the throttle slide back onto the throttle cable. Put the throttle cable through the top cap of the carb and put the spring on. Put the needle in the slide and compress the spring and hook the end of the cable on to the slide. Before sliding the slide into the hole, make sure the slot in the slide is lined up with the idle screw. When they are lined up, slide the throttle slide in and screw the top cap on. To set the baseline for the idle screw, look down either hole of the carb and screw the idle screw in. When the slide starts to rise, screw the screw in half a turn.
Picture 2: Slide and wiggle and carb back into the rubber boots. Tighten the screws on the clamps to hold the carb into place. Install the fuel line and overflow line to the carb.
The last step of the project will be to adjust your air and idle screw, to do this the engine must be running. If you want to increase the idle, screw the idle screw in. Screw the air screw out to richen and in to lean out.