Many riders won't think too much about their motorcycle carburetor unless they encounter a problem with theirs. This typically occurs with older carburetors or ones that haven't been looked after well enough. For example, you might only notice your motorcycle carburetor needs attention because it's getting poor throttle response. There again, it could be that your motorcycle carburetor needs attention because the engine idles too high. Lots of black smoke may indicate a carburetor that is running too rich, while one that isn't rich enough—in terms of its air and fuel mix—could lead to engine knocking sounds. In addition, motorcycle carburetor problems sometimes cause poor fuel economy, with nothing other than an uptick in the number of times you need to refuel to indicate any sort of issue at all.

Consequently, it is worth knowing more about your motorcycle carburetor, how it works, and what you need to do to keep it operating in top condition. In this ultimate guide to motorcycle carburetors, you will find out everything you need to know, which should mean you never encounter the sorts of problems that faulty or improperly maintained ones can lead to. Read on to find out more about motorcycle carburetors.

What Is a Motorcycle Carburetor?

To kick things off, a motorcycle carburetor is a mechanical device that's often a part of a bike's engine, especially older models. It operates just before the combustion chamber by mixing fuel and air together, ready for it to be ignited inside. This is crucial because all combustion engines, whether they're fitted to a bike or not, need an appropriate amount of air and fuel to run efficiently. Too much fuel and not enough air is known as being too rich, while the opposite—too much air and insufficient fuel—is known as running too lean.

How Does a Motorcycle Carburetor Work?

A motorcycle carburetor mixes air and fuel together, sending it to the engine in a mixed state for combustion. When you pull on your motorbike's throttle, more air is allowed into the carburetor via its venturi. Meanwhile, fuel is stored in a float bowl. If more air comes in due to the throttle being deployed, a corresponding amount of fuel will be drawn in from the float bowl. As such, the mix levels are maintained, regardless of how open or closed the throttle happens to be. This way of working can be overridden, however, if the carburetor has a choke, which forces more fuel into the mix temporarily.

Does Every Motorcycle Have a Carburetor?

Not every kind of motorbike engine has a carburetor. This is because many modern motorcycles have an electronic fuel injection (EFI) system instead. These systems do the work of mechanical motorcycle carburetors, and, what's more, they do so automatically, with fine adjustments being made for different riding conditions. For example, some EFIs will adjust the fuel mix if you happen to be driving at high altitudes. The same goes for riding on a hot, sunny day, as opposed to a cold winter one.

Other than the convenience of EFIs, they've replaced motorcycle carburetors in modern bikes because EFI is often deemed as being more efficient. This is only partially true, however, because it depends on how well the carburetor on your motorbike is maintained. Some manufacturers also consider electronic fuel injection systems to be the cleaner and more environmentally responsible option, as they help to prevent the spread of unwanted particulates in the air. What's more, they can cut down on fuel consumption.

That being said, you will often find a motorcycle carburetor is the best option on bikes with smaller engine capacities. Many motorcycles with engines under 250cc still use carburetors, for instance. They remain the norm on learner-legal 125s, as well as a number of off-road or trail bikes. Some new commuter bikes that aren't designed for long-distance rides also still make use of motorcycle carburetors in their design. Essentially, where affordability is a key buying consideration, motorbike manufacturers still rely on carburetor technology, which is tried and tested.

Other than that, motorbikes manufactured before EFIs became commonplace still often have mechanical carburetors to mix the fuel and air. Typically, motorcycles made before 2000 will have carburetors. In addition, some bikes that were made to look and feel like older vintage models will have motorcycle carburetors fitted to them instead of EFIs because this is what certain types of owners want from their rides.

Parts of a Motorcycle Carburetor

There are several components that go into the design of a typical motorcycle carburetor. The first is a float chamber that, in effect, is a fuel reservoir, which the carburetor utilizes to obtain the fuel it needs in precisely the right quantities. Jets—sometimes known as needle jets—regulate the flow of fuel and air, mixing them together in just the right proportions.

A throttle regulates the airflow and the engine's speed. Some have slide throttles, while others have butterfly valves. This isn't so important, as understanding what the throttle does, though. Essentially, they both open when more power is wanted. Doing so allows for greater airflow into the carburetor. In turn, inwardly rushing air creates a lower pressure state in the device. This automatically draws through more fuel, with a richer mix of both air and fuel. In turn, this generates more power to the engine. So, when you turn your bike's throttle, you're actually influencing the way the carburetor works, not the engine itself.

Lastly, some motorcycle carburetors have chokes. What deploying a choke will do is temporarily enrich the fuel mix. You might need this if the bike hasn't been ridden for a long time or if it happens to be a cold day when starting the bike up. Once the motorcycle runs for a few minutes, you should release the choke back to its usual position to prevent excessive fuel consumption or flooding the engine.

How to Clean Your Motorcycle Carburetor

Dirty motorcycle carburetors cause problems of hard starting, excessive fuel consumption, and rough idling, among other issues. More often than not, a simple carburetor cleaning is all that is required to address these symptoms of a dirty carburetor. To begin with, you will need to remove your motorbike carburetor. You can read about how to locate it and what you need to do to access it below.

Tip: A good tip to remember when removing the carburetor is that it will need to go back in place just as you found it, only cleaned up, of course. Taking photos of it in place with its various clamps, air intakes, and fuel connections will help you put it back just as it was.

Once removed, an external clean of the carburetor is advisable. There are specialist motorcycle carburetor cleaners on the market, which are ideal for this job. You can get away with a motorcycle brake cleaner product, an all-purpose cleaner, or even white vinegar, but a specialized product is preferable for this job. Spray it all over the unit. Next, remove grime by gently scrubbing the cleaner in with a small brush—an old toothbrush is often a good idea. Allow the carburetor to dry out, or blow it dry with a canister of compressed air. Wipe the motorcycle carburetor down with a clean rag before replacing it.

If you want to clean the internal parts of your motorcycle carburetor before reinstalling it, then you need a clean surface to work on, making sure the components won't become contaminated. To do so, remove the float bowl. You can do this by unscrewing it from the underside of the carburetor. This will allow you to take out the float, the needle valve, and the float pin for individual cleaning. Some carburetors allow you to unscrew the jets, too—the pilot jet and the main jet. After that, you can sometimes reach the jet needle and diaphragm and strip these parts out, as well.

When some or all these internal parts have been removed, you will be able to spray motorcycle carburetor cleaner into the unit. Use a fine wire to help it reach all parts inside the carburetor, but don't be too forceful since it is easy to damage delicate motorcycle carburetor parts. Soak any items you have removed in the carburetor cleaner. Blow everything dry, including the inside, to remove residues before reassembling and installing the carburetor.

Where is the Carburetor on a Motorcycle?

Knowing how to clean your motorcycle carburetor is one thing, but where to find it so you can do so is quite another. Look for the engine's intake manifold. The carburetor will usually be positioned between it and your air filter. Most motorbikes have these parts situated somewhere under the fuel tank, so yours should be reasonably easy to locate. Multi-cylinder motorbikes may have more than one carburetor—one for each cylinder—but this is not always the case, especially when it comes to smaller motorcycles.

If you're still not sure where your motorcycle carburetor is, then follow these steps:

• Turn the motorbike's engine off and disconnect its battery, removing the negative terminal first.

• This will allow you to unscrew the seat and lift it off, but make sure your bike has been properly stabilized before doing this.

• Disconnect your bike's fuel line, taking care not to spill any fuel that may be in it, so you can remove the fuel tank from the bike—depending on your model—you may also have to disconnect other components, such as vacuum hoses, for example.

• Unscrew the fuel tank and take it off the bike.

• You should now be able to see the carburetor—what you're looking for will be a metal device close to the intake manifold with throttle cables, rubber intake boots, and a float bowl on the underside.

How Often Should You Clean Your Motorcycle Carburetor?

If you tend to ride on muddy tracks or dusty roads, then it is likely your carburetor will pick up more dirt than average. There again, if you haven't ridden your bike for some time, then fuel may become stale in the carburetor, leading to an unwanted residue build-up. Overall, you should clean your carburetor—with motorcycle carburetor cleaner—about once a year or every 10,000 miles you ride.

Note that if you use fuel blended with ethanol, you may need to clean your motorcycle carburetor more frequently. This is because ethanol can absorb more moisture than regular fuel. As a consequence, it can lead to more blockages in carburetors over time due to gumming. Ethanol is also more corrosive, generally speaking, which is another good reason to increase the frequency of your carburetor clean-ups.

How to Tune a Motorcycle Carburetor

You can tune a motorcycle carburetor before or after cleaning it. Most bike owners will want to clean their carburetor and reinstall it before tuning, though. This is because tuning a dirty carburetor will sometimes mask more serious and underlying faults. By comparison, tuning a freshly cleaned motorcycle carburetor should mean you get the best results from the process. Either way, here is what you will need to do:

• Don't tune up a cold carburetor, so allow your bike to idle for a few minutes or give it a light ride to warm it up.

• Next, adjust the idle speed to match the recommended RPMs according to your owner's manual. This will usually be somewhere between 1,500 and 2,500 RPM, depending on the model. You do this by turning the idle speed screw on the side of the carburetor. Clockwise augments the idle speed while a counter-clockwise movement lowers it.

• There's another screw that allows you to adjust the air and fuel intake mixture. Once you've located it, you can easily adjust the richness of the mix. Clockwise adjustments make the fuel intake leaner, while counter-clockwise ones increase the amount of fuel being fed into the carburetor.

• To fine-tune the air and fuel mix, turn the screw counter-clockwise until the bike stalls. Then, move it in the other direction until the idling is smooth—a one-quarter turn back in the other direction usually means finding the right balance between fuel and air.

• To tune the throttle response, you may need to re-adjust the idle speed screw to get it back to the recommended level per step 1. When the engine is idling, apply your bike's throttle. The engine should return smoothly to its correct idle speed without spluttering or running too fast. If this is not the case, then go back to step 2 and repeat the process with the new idle speed setting until it does. You may need to repeat these steps a few times until you get the right response.

• Finally, take your motorbike out for a short ride and then inspect the spark plugs, which will help you assess the performance of your motorcycle carburetor. If it is black, then the fuel mix is still too rich. If it is white, then the mix is too lean. A light brown color indicates you've tuned your carburetor perfectly.

How to Remove Your Motorcycle Carburetor

Follow the steps outlined above for assistance with locating your motorcycle carburetor. Once you have done that, the following steps should be followed if you want to remove it.

• With the seat and fuel tank removed, you may still need to remove the airbox—the chamber that holds your motorcycle's air filter—for better access to the carburetor. In some cases, you might only need to loosen the clamps that secure it for better access.

• With a set of pliers, disconnect the fuel hose if you have not done so already, using a tray to catch any drips that escape from it during this step.

• Disconnect any vacuum hoses or intake pipes that connect to the motorcycle carburetor.

• Make a note of the position of the carburetor's throttle and choke cables, as you will need to reconnect and disconnect them in the same place.

• Loosen the clamps that hold the carburetor in place and gently wriggle the unit until it becomes free.

• Remove the carburetor without forcing it too hard, and plug its intakes to prevent dirt and debris from accidentally entering the unit.

• Your motorcycle carburetor is now ready for refurbishment or repair.

How to Rebuild Your Motorcycle Carburetor

When you rebuild a motorcycle carburetor that has been stripped down for cleaning, it is important to work in reverse order. In other words, the last component you removed should be the first one you reinstall. It is very important that all the motorcycle carburetor cleaner you've used to clean the device is removed, which you can do using a can of compressed air to force it out. Proceed with all of the parts of the carburetor you removed, ensuring none have picked up any oil or grime from your worktop. Once all of its sub-components have been refitted, the last thing you should connect is the float bowl.

Once the motorcycle carburetor has been rebuilt, put it back in place and adjust the clamps that hold it between the engine and the bike's airbox. You will need to reconnect the throttle and choke, as well as the fuel line and the air intake pipe. Taking photos of exactly how they line up before removing an old, dirty carburetor can be invaluable at this stage, especially if you have never done this sort of motorcycle maintenance work before.

Conclusion: Key Points About Motorcycle Carburetors

Knowing how to maintain and access your motorcycle carburetor isn't just relevant from the perspective of resolving performance issues. Why? Because it is about maintaining the value of your bike for years to come. Even if you are already in the habit of routinely removing and cleaning your carburetor, it's also wise to be able to recognize common problems that indicate an issue has developed with your carburetor prematurely. Anything from blocked jets to poor fuel economy and erratic idling are signs your motorcycle carburetor is in need of attention sooner rather than later.

Motorcycle carburetor cleaning helps avoid many of the most common problems, especially after a period of long storage or after using your bike in mucky conditions. This sort of maintenance work can be particularly beneficial if you ride in dusty locations, where fine particles can make their way into the air intake, bypassing the bike's air filter. Riders of ethanol-blended fuels will also find that more frequent motorcycle carburetor cleaning will be in their interests.

What's more, it's important to use the right tools when dealing with your carburetor. Basic hand tools for removing the seat and fuel tank are all that's needed, while a screwdriver is often sufficient for tuning. However, a specialized motorcycle carburetor cleaner and a can of compressed air aren't commonplace, but using them can make all the difference in the outcomes you can obtain from this sort of bike maintenance. Equally, observing safety measures—such as disconnecting the battery and draining fuel lines properly—will make the job not only safer but easier, too.

To sum up, by staying on top of preventative maintenance and recognizing the early signs of a poorly tuned carburetor clogged with dirt, you'll extend the life of your ride. For many motorcyclists who love classic bikes, which most likely feature carburetors, keeping their motorcycle fit is something that should never be overlooked.