How to Clean a Motorcycle Carburetor (Without Removing It)

The carburetor, or simply the carb, is one of the most important parts of any vehicle. It acts as the engine room of your motorcycle. The role of the carburetor has been compared to the place of the heart in the human body. The logic of the motorcycle is that ‘the more the airflow, the more the horsepower.’ Of course, you know the carb is only used in petrol engines.

As a device that supplies fuel to your bike engine, the carburetor controls the quantity and quality of the air-fuel mixture that enters the engine cylinder. The carb mixes air and fuel for internal combustion engines. This mixing is always done in the proper air-fuel ratio for combustion. It is important that the rider takes every preventive and proactive measure to prevent the carburetor from getting dirty or blocked. In simple terms, there must unobstructed airflow into the carburetor. Based on the direction of the supplied air-fuel mixture, a carburetor can be divided into three types. They are, the Up-draft carburetor, the Down-draft carburetor, and the third is the horizontal-type carburetor.

The mechanism of the carburetor is simple. When air with velocity flows above a cylinder, it causes a pressure decrease. At the other end of the cylinder, there is a dip in the fuel. What happens is that the fuel rises in the cylinder and is carried away by air.

But once it is established that the carburetor is having an issue, the rider must take very seriously all necessary steps to address it before it gets out of hand. One of the main problems that the carburetor often encounters is blockage.

My concern in this post is to explain the step-by-step approach to cleaning a carburetor without having to remove it. The rider must try as much as possible to discourage the repairman from removing the carb while trying to clean it. What you find out is that the carb has so many tiny parts that may get lost in the course of removing it from the engine. This is one reason it is not advisable to uncouple the carb from the bike before cleaning it. I bet you, it really can be a nuisance taking the carb from the bike for cleaning.

But do you deny or doubt this is possible? If you do, I am here to clear that doubt and tell you without mincing words that it is obviously possible to clean a carb without having to go through the hassle of detaching it from the bike. I have done and tested it and made a success of it. I am not just cooking up a story or making a hypothesis that won’t work. This is my over- two decades in this industry and I think I am on the right stand to tell you how this is possible.

Ready to learn? Let’s get down to business.

But just before then, to have a proper cleaning and seamless process, the following items and supplies should be made available:

Supplies Needed to Clean Your Carburetor

Carb and choke cleaner
Carburetor and parts cleaner (recommended)
Gasket set or carb rebuild kit

Cleaning Carburetor without Disassembly

There are certain things you have to know and steps to follow before you begin the process of cleaning the carburetor. Typically, the elements of internal combustion engines should be in the right air-fuel proportion. Two, elements should spark at the right time without a turnover; the third thing is that the elements should have adequate cylinder compression.

1. Take Off All Rubber Parts

Before you begin, try to remove all the rubber parts of the carburetor. These parts include hoses, O-rings, needle valves, and vacuum diaphragms. If you don’t take this first step, spray cleaner is no friend to the parts and will destroy them. I repeat, never disassemble the carb from the carb brackets.

2. Remove the Air Intake Filters

The second preliminary step to take is to completely take off the airbox or pod filters. You can seamlessly reinstall and set them up once you’re done with the cleaning. Once you remove the air intake filters, the rear of the carburetor naturally gets exposed, and that allows you to be able to see the opening and closing of the butterfly valves when turning the throttle.

Through that, you are able to see the carburetor and gain unhindered access to it. From there, you can take off the bowl at the bottom of the carburetor.

3. Take out the Screws

You’ll need to remove the bolt or a few four pan head screws that hold the float bowl and encircles around its side. This is to make sure that the float bowl is detached. Ideally, within five minutes or so, you should be able to remove these screws. However, you must unscrew these screws with utmost care to avoid them stripping very easily. Do not start to clean the parts yet. I will tell you when we get to that stage.

4. Turn Off the Petcock

The next thing to do at the preliminary stage is that you turn off your petcock. This is to avoid running the gas out of the cock. While doing this, hold in your hands some paper towels. They will help you prevent any gas leakages that may arise as a result of the taking off of the bottom bowls.

5. Loosen the Clamps

There is also the need to loosen the clamps that hold the carbs to the intake manifold. Besides, bend each of the clasps that are fastened to the coolant hose to allow the hoses to extend to give you ample room to spray and work on the carb. The clasps are located on the chaincase and the clutch sides.

6. Detach the Jets

It all depends on the kind of carb your motorcycle is using. So, understand that this next step will differ based on your bike carb type. Some carbs have splash plates; others don’t. Regardless of the carb type, the jets need to be taken off. By jets, I mean those screws that have a hole that passes through their center through which the fuel flows to mix with air.

Typically, the main jet is short and fat; it is also built to have a hexagonal head shape or a flat screwdriver head. However, the pilot jet is typically long and skinny. It requires a flat head screwdriver to remove. I will discuss the process of cleaning the jets shortly.

7. Remove the Air & Idle Screws

We have to go through the last step before we start to clean our carburetor. Now, it is time to remove the parts of the carb from the outside. With the help of a flat-head screwdriver, you can remove the air screw and the idle screw. These screws are often found on the sides of the carb. Meanwhile, the idle screw is the larger of the two screws and it helps to adjust your motorcycle idle when the engine is in idling mode. The smaller screw (air screw) adjusts the airflow through the carb when the engine is running.

8. Start With a “Trial” Procedure

Do not forget to remove the three-pronged fuel lines that connect each carb and link it to the fuel pump. Having taken the preliminary step, it is now time for us to go straight into the actual process of cleaning the carb, based on the parts-by-parts cleaning procedure.

The float is the base of the carburetor and it is the first part to be detached from the carb when cleaning the carb. To remove the float, first, take off the float bowl. To remove the float, you need to take off the float pin. You can achieve this effortlessly by pulling it out with a pair of needle-nose pliers. Not until the pin has been removed should you think of removing the float. Meanwhile, in some carburetors, the needle will not come out on its own but will hang on the float and possibly come out alongside it.

Now that the float bowl is off and other preliminary processes have been carried out, it is time to start to spray some carb cleaner up inside the device. Start with doing a few sprays within minutes. This process is to ensure that any dirt or grime on the carb is loosened. After that, reattach the float bowl. Ignite and start up your motorcycle and listen to the sound it produces.

That’s like a trial. It may turn out perfect; on the other hand, its result may not be what you expect. If the procure doesn’t give the required outcome, you’ll have to take the steps further.

Turn the float bowl off and observe the floats that rise inside of the carb. These floats occur after the carburetor has received a signal from the gas-filled bowl that it should shut out the fuel valve from flowing over. Now is the time to take off the float so that you can have access to its rear part. Once it is removed, you observe that a part that has a rocket ship shape linked to it with a rubber tip. Both the rocket ship-shaped part and the tip will detach together.

It is advisable to test the functionality of the floats especially once they are off. How do you do that? Put the floats into a bowl of liquid (preferably water) to see if they truly float. If they fail to float, kindly get new ones. If you don’t replace them, you’ll be inviting mechanical issues to your motorcycle.

Cleaning the Carburetor

So far, I have explained to you the preliminary and removal steps to take. We are set to begin the process of cleaning our carburetor. It is not difficult at all. Choose the method you want to use for the cleaning. Just before we start, however, it is important to remove all gaskets and O-rings.

Generally, the most effective and easiest way to clean the carburetor and the parts are to soak them in a gallon of carb and parts cleaner. Let me say that the can is a little costly for just one use. Carb parts can also be cleaned by spraying carb and choke cleaner.

Safety measures require that you wear safety gear including glasses and gloves. They are necessary, They are recommended for cleaning. To start the process of cleaning the car parts, scrub them with a wire brush and then spray with carb and choke cleaner jets. Spray the holes from which the jets, the air, and idle screws, float needle, and choke come.

Jet Cleaning

The process of cleaning the carb jets, whether it is the primary jets or secondary jets, is to first inspect the jets. How do you do this? Hold light and look through the jets. You should be able to see an unobstructed round hole. If not, then know that there is some dirt in the jet. Clean the jets with any of the combinations of two of the following substances: compressed air, soak solutions, carb spray cleaners, or cleaning wires. Spray the cleaner into the holes of the jets.

After doing that try to re-inspect again to see if the hole is see-through. After that, try to install the jets. The process of installing the jets is dependent on the type of jets your carb is having. We have jets that come in the form of paper-like gaskets. There are some like the metal spacers, something in the form of a jet, and the emulsion tube. The third type of carb jet is that which screws directly into a brass emulsion tub with the exposed base chamber.

Unscrew both the primary and secondary jets once the float is off. Once the jets are out, check if the jets are transparent enough. If you can’t see through them, it may have been that some ethanol gas is used which usually clogs them. Do some proper cleaning of the jets to do away with the junk and debris.

Inlet Fuel Valve

This is one process, like every other stage, you shouldn’t miss or forget. If you miss it, you are likely to repeat the whole process all over again. First, inspect the needle valve and spring by pressing down the tiny metal rod that shoots out from the base or float end of the needle valve. What are you looking for? Make sure the spring moves freely and returns the rod to its location. The seating area of the needle valve should appear sharply polished. No wear, no groove. If your needle valve seats are made of rubber, it may be difficult to see the wear.

The next step is to inspect that jet seat and then clean it. You can use the Q-tips and semi-chrome polish for the cleaning.

Carburetor Body Castings

This is one technical aspect of the cleaning. Start by blowing air through the atmospheric vent holes. These holes are located on the vault of each float bowl cavity. Make sure that air finds its way out through the hoses or brass nipples.

Check the emulsion tubes and passageways to see if there is any debris or discoloration. The passageways are the cast towers into which the jets thread. Try to clean the interior of the emulsion towers with a supple bristle gun cleaning brush. Don’t forget to clean the main carb bore.

Throttle Slides

As you may be aware there are several kinds of throttle slides. There is the vacuum, diaphragm, mechanical linkage, and cable. You don’t need to disassemble the jet needle from the throttle slide before cleaning. If your carb operates with the vacuum piston type of throttle slides, don’t clean the lubrication from sides and caps. Otherwise, check cap vents and passageways with air. Check for dry-rot, defects, and tears if you have rubber vacuum throttle diaphragms by gently stretching the rubber away from the center. Replace any defective parts. Avoid pinching the diaphragm when reinstalling caps.

Fuel Screws

Fuel screws are part of the choke circuit. Typically, they have sharp pointed ends. They are fragile and can easily get damaged especially if it goes beyond their tightening limit. It is important that you carefully turn one fuel screw in as you count the turns until it sits lightly. Cont the number of turns-in while you take off the fuel screw, washer, o’ring, and spring.

Post-Cleaning Stage

This stage is as crucial as the first stage. After cleaning the carb and its parts, you’ll need to make sure all debris and gunk are removed from the carburetor. Then, you need to dry the carburetor and all parts. The easiest way to do this is to use compressed air. How do you go about this?

It’s simple. Blow compressed air into all holes, and blow off all parts of the carb. Ensure that everything and every part is dry. Once this is done, you can start to install the new o-rings and gaskets back into carb. However, if you don’t have them now, you can reuse the old ones provided they are still in good condition.

The final step is to start your motorcycle, wait for some minutes to listen to the sound, and observe whether your motorcycle runs well or not. But I am sure it runs well except you don’t follow these processes as outlined. If you need to access the carb again, try not to install the air intake filters. But once you can give the carb’s work a pass mark, then, set up your air filters.

Taking the Final Steps

Spray the carb all over again using the carb cleaner.
Hold on for some minutes and allow the cleaner to drip off all gunk before you reinstall the carburetor parts.
Reinstall the jets and the float
Install the bowl on the bottom

Installing the Jets and Other Outer Parts

After the jets have been installed, the other parts of the carburetor can be installed. It is best the installation it with the outer parts of the carburetor. To begin with, start with the choke, then the air screw and idle screw. When installing the air screw, that is, the typically long and skinny screw, rivet it in and back so that you screw out a turn and a half. This is the baseline. You can later adjust once the engine starts to run to allow the proper idling of the engine.

On the other hand, to install the idle screw, that is, the short and fat screw, screw in just enough to hold it. It doesn’t have to be fastened tightly like the air screw. The baseline adjustment can come in later after you have run your engine.

The next part to be installed in the line of things is the float. How do you install the float? It’s simple. To install the float, line the holes up with the holes in the carburetor and slide the float pin in. The pin should naturally slide around freely. All you need to ensure is that the pin is centered to ensure it is secure. It is important to never overlook testing whether the float needle works properly. To achieve this, move the float up and down to ensure the needle moves freely. If you discover that the needle gets stuck in the up position, you must replace it.

After this is the installation of the float bowl. Please, do not jump through these processes and steps. Otherwise, you may have to start all over again, and you can be sure the stress is not worth it. Installing the float bow is easy. Use the 4 screws on the base of the carb. Having done all these, your bike carb should be complete by now, without the throttle.

How Often Do You Need To Clean The Carburetor?

Well, just as you take out your bike for scheduled service, the carburetor is no exception. It is an important part of the motorcycle and its components that shouldn’t go unattended. Cleaning the carb requires routine maintenance. Do you need to be reminded that your body that is often put to work needs a lot of medical checkups regularly? I don’t think so.

Do not be confused about the type of maintenance that you need to carry out on your carburetor. Meanwhile, the popular rule of thumb is that the carb should be tuned and cleaned every two years. I will recommend that apart from the routine service, your carburetor should be taken for routine maintenance every year.

It has to be said that the frequency of the use of your motorcycle will also depend mainly on the frequency of the service of your carburetor. If you regularly ride your bike, you’ll need to take it out for cleaning sessions as often as possible. Meanwhile, some carbs could need to be tuned up every few months; others may require that they are tuned up every few years.

This is not to say that those who ride their motorcycle less often will have to wait for years before attending to their carburetor. No. Riders in this category should clean their carbs more often. This is because when motorcycles become dormant and unused for some time, there is a tendency for the carburetor builds up grime and dirt inside it and will need to be cleaned as regularly as possible.

There are different methods you can use to clean your carburetor. We have the soda method, soda blasting, the ultrasonic method, and hot water. Each of them has its own advantages and downside.

Methods of Spraying Motorcycle Carburetor

Soda Method

If you’re using the Soda technique, the following advantages are there:

Soda Advantages

It doesn’t remove metal or damage any plating/surface finish.
Removes grease, dirt, gasket material, rust residue, and crusty stuff.
Readily dissolves in water. No grit or particles remain in the carb.
Safe to use on rubber and plastic carb.
Flows through a passageway and thoroughly cleans it.
It’s cost-effective: With about $40, you can get 50 lbs of soda.

Soda Disadvantages

It takes several rinse cycles before it removes all remnants. Meanwhile, the best approach is to blow with compressed air to remove as much gunk as possible before rinsing.
It may plug up very small passages like accelerator pump passages, but it rinses away in water!
It tends to plug up blind holes.
Soda is supposed to be a one-time use media since it breaks down into powder on impact.
It does not handle corrosion well. This is not a media for restoration.

Ultrasonic Cleaner

I have extensively discussed the ultrasonic cleaner, especially as I take you through cleaning your carburetor. If you apply the soda blasting method, you don’t need the ultrasonic technique again. The only difference is that the machine does the work for you if you’re using ultrasonic.

Ultrasonic Advantages

It saves time and is cost-effective
The machine does the work of spraying
An ultrasonic cleaner uses water-soluble detergents, rather than harsh chemicals, to break up residue, making it eco-friendly
Ensures worker safety: prevents you from inhaling harmful chemical fumes and also helps to avoid contact with sharp, biologically contaminated instruments
Makes gentle cleaning: ultrasonic cleaner allows the mixture of water and detergent to reach into narrow crevices of our carb and remove unwanted residue.
Efficiency: uses less water than most hand-cleaning methods. Also, it conserves energy, making it energy-efficient.

Ultrasonic Disadvantages

Not cheap to use
Requires skilled operator: one has to go through the user manual before the start of the cleaning process.

Frequently Asked Questions

What To Do When Your Cleaning Wasn’t Enough? Well, if you do your job correctly and are faithful to the procedure of cleaning the carburetor which I have given, there shouldn’t be any fear of whether your cleaning isn’t good enough. The process is exhaustive, but because the cleaning is done without taking off the carburetor from the engine, there’s the likelihood that there are other parts not adequately touched. It’s possible to clean the carb, and it won’t give the best result you desire. If that happens, there are steps you can take to take care of the problem.

I may have to say that there might be some other underlying issues within the carburetor that you may need to consider. This may not have anything to do with the fact that you did not remove the carb from the engine.

To address that, the solution most times is to go the whole hog to take off the carburetor from the motorcycle. The process may be an intimidating and complex task. If the DIY cannot work, you may need to engage the service of a professional carb cleaner.

But be reminded that some of the small component parts of the engine may be lost; since it is a professional who’s handling it, then you need to relax and try to find out how it is done.

Straight to your answer: all you need to do if you feel your carburetor is not adequately cleaned with the first procedure is the following:

Buy an ultrasonic cleaning solution.
Place the carb part inside it.
Turn the ultrasonic cleaner on and allow it to clean the carb.

To avoid the cracking and annoying noise that will come from the process, try to carry out the cleaning in a room that is far from people.

Alternatively, here’s another piece of good news. There are many videos and online forums where you can get answers to cleaning your carburetor by removing it from the motorcycle. Let me share some ideas with you. If you detach your carburetor from your bike and set it apart from the engine, you can put it in an ultrasonic cleaner. There are lots of them online.

What can I use to clean a carburetor? This is one question that riders must pay close attention to. The carb is one delicate and sensitive part of the vehicle, and you can’t afford to just dip anything into it in the name of cleaning. No. what I often recommend as the easiest, best, and most cost-effective way to clean the carb and the parts are the use of parts cleaner. Simply soak the parts in a gallon of carb and parts cleaner. Alternatively, the carburetor parts can be cleaned using the spray method. Spray the carb and choke cleaner. Be faithful to the instructions on the cleaning

How much does it cost to clean a motorcycle carburetor? You cannot always predict the cost of cleaning your bike carburetor can incur by merely looking at it from face value. It all depends on the extent of the service that needs to be carried out on the carburetor. Typically, cleaning a carburetor can cost you something in the neighborhood of $200 to $300.

However, if the service requires that you replace your bike’s carburetor, it may attract something in the region between $500 and $800 in total. That, again, also depends on the model and brand of a carburetor you’re buying. Trust me; carburetor cleaning isn’t as complex a task as it might seem.

How do I know if my motorcycle carburetor needs cleaning? I’ve said it before, but let me reiterate that the most typical problem the carburetor always has is clogging and blockage. Once there is too much dirt in the carb and the jets are clogged, airflow through the passage of the carburetor is obstructed.

One interesting thing about carburetors is that they have a way of communicating to riders about their conditions. They tell us what they need and whether they are in a good or bad state. There are a few of those signs you should look out for to tell that your carburetor needs cleaning.

The jets are a great part of the carburetor that serves an incredible role in the overall functionality of the carburetor. However, once they are clogged, they often give off signs that the carburetor is in a bad state by causing serious mechanical issues for your motorcycle.

Essentially, issues like backfiring, poor idle, sputtering, and just poor running of the engine are common signs that your carburetor is dirty. For me, these signs are extreme; I am not sure I can wait until these signs come up before I take pretty quick action. But I am aware that my carburetor is the first culprit. So, I try to clean the carburetor.

The consequence of this is that your engine cranks or turns over. The engine starts to run lean. The required amount of air and fuel mixture can’t go through the engine passage.

Where do you spray carb cleaner? If you want to spray your carburetor, you have to be careful so that you don’t cause more damage to the device. To do that properly, place the tip of the aerosol canister into the middle of the carburetor and apply the spray directly to the running carburetor.

It’s important the spraying is carried out while the engine is running. Doing this will allow the cleaner to penetrate deep inside and clean the carburetor’s inner parts, including the throat. It will also remove the debris in the device’s lower throttle plate.

Types of Carburetors

There are three types of carburetor, up-draft carburetor, horizontal carburetor, and down-draft carburetor. If air is supplied into the device from the base of the mixing chamber, we call that one up-draft carburetor. If it is supplied from one side of the carburetor, we call it a horizontal carburetor. However, if the air is supplied from the top portion of the mixing chamber, we call that one down-draft carburetor.

Motorcycles generally have the down-draft type carburetor because of its unique advantages. One of that is that gravity assists the flow of the air-fuel mixture. What that does is that the engine pulls better at a lower speed when it is loaded. Also, the down-draft type carburetor offers the engine capacity to achieve a higher value of volumetric efficiency. The third thing to admire about this type of carburetor is that it allows for easy access to the carburetor.

Conclusion

I have been able to let you into the process of cleaning a carburetor without uncoupling the engine. The passages and openings in the engine need to be regularly checked and cleaned. This is because once these channels are blocked or not working properly, they create a radical effect on the engine’s performance.

You should also know that once there are vacuum leaks or the carburetor is synchronized, there’s also an effect on the overall performance of the engine and the bike. Try to inspect and adjust if you follow the procedures I have outlined.

In my over two decades of experience and romance with the automotive industry, I have often been asked whether it is appropriate to clean the carburetor with water. The good news is that a bucket of hot water can do the same cleaning the ultrasonic cleaner will do. You don’t always have to rely on the ultrasonic cleaner after soda blasting. The machine can always do it for you. The ultrasonic system saves you a lot of time.

Does it take forever to be able to clean a carburetor? I do not suppose so. There is a world of difference between the DIY style and the professional cleaning of the carburetor. It all depends on the bike. For a single a single-cylinder engine bike, it may take you something in the region of 2 to 3 hours or so to complete the entire cleaning. Within 20 minutes, you should be done removing the parts (tank, connections, subframe, and carb). 30 to 40 minutes should be enough to remove the brush, take it apart, and soak it in cleaner. Meanwhile, you spend about 50 minutes estimating major faults or worn items. You may spend less than 2 hours cleaning and assembling all the small parts.

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How to Clean a Motorcycle Carburetor Without Removing It