This guide is for motorcycle carburetors, especially slide carburetors. Similar principles apply to other types of carburetors.
Have you had issues like a new carburetor leaking fuel? Or your motorcycle using more gas? Or it won't start after winter?
These issues are typically caused by dirt and grime inside the carburetor. Poor maintenance can even lead to a 15% loss in engine power.
Here, I will guide you step by step on how to clean a carburetor, emphasizing the importance and frequency of cleaning.
Cleaning a carburetor may seem complex, but with the right guidance, it’s quite manageable. All it takes are a few basic tools and some patience. Let’s get started—your bike will thank you, and your rides will feel refreshed.
If you’re already familiar with carburetor basics, feel free to skip certain sections.
Understanding the Function and Basic Structure of a Carburetor
The primary functions of a motorcycle carburetor include:
- Mixing fuel and air: It mixes fuel (usually gasoline) and air in precise proportions. This gives the engine the right mixture.
- Controlling the ratio: It regulates the fuel-to-air ratio to ensure efficient engine performance.
- Delivering the mixture: It sends the prepared mixture to the engine's combustion chamber.
The carburetor works on the Venturi effect. As air passes through a narrow channel, its speed increases and pressure drops. This draws fuel into the airflow, making a combustible mixture.
In simple terms, the carburetor acts as the engine’s “heart,” supplying it with the appropriate fuel-air mixture to keep it running smoothly.
Basic Structure of a Motorcycle Carburetor
Overall Carburetor Construction
When fully disassembled, a carburetor consists of many small parts. For someone unfamiliar with carburetors, it can be overwhelming to remember the location of every piece.
It is recommended to photograph each component as you disassemble the carburetor. This prevents confusion or wasted time when reassembling.
Key Components for Cleaning:
- Fuel Bowl: The chamber that stores fuel.
- Venturi Tube: A narrow passageway for accelerating air flow.
- Main Jet: Supplies primary fuel.
- Pilot Jet: Supplies fuel at low speeds.
- Needle Jet: The primary outlet for fuel.
Why Clean the Carburetor?
With fuel leaks or poor mileage, replacing the carburetor may seem best. But, cleaning it is often the solution.
The carburetor is a complex assembly of small, precise parts. Imagine it as your nose and the engine as your lungs. When you have a stuffy nose, breathing becomes difficult and uncomfortable. Likewise, dust, oil, and grime in the carburetor block airflow. This hurts engine performance.
Benefits of Regular Carburetor Cleaning:
- Improves engine efficiency and saves fuel.
- Enhances fuel economy, preventing issues such as engine knocking or stalling.
- Protects the engine from damage caused by residue buildup.
- Avoid costly repairs by acting as preventive maintenance.
- Prolongs the life of the carburetor and related components.
How to Identify When Cleaning Is Needed
Over time, dirt, varnish, and residue accumulate in the carburetor, causing performance issues. Here are common signs:
- If the engine struggles to start, the carburetor may be clogged.
- Poor acceleration: Delayed response during acceleration indicates disrupted fuel flow.
- Unstable idling or stalling: An improper air-fuel mixture causes stalling and uneven idling.
- Black smoke from the exhaust: Blocked air passages lead to overly rich fuel mixtures.
- Reduced fuel efficiency: An unbalanced air-fuel mixture increases fuel consumption.
- Engine misfires or surging: Irregular power delivery is caused by inconsistent fuel flow.
- Fuel leaks from the carburetor. This often happens when the float is stuck or not sealed properly.
- Loss of power: The engine cannot reach its full potential, especially under load.
- Check the carburetor for visible dirt or grime. It may need cleaning.
Recommended Cleaning Frequency:
- Preventive Maintenance: Clean every 2,000–3,000 miles or as part of routine servicing.
- Before Long Storage: Prepare the carburetor before storing the vehicle.
- After Storage: Residual fuel can clog the carburetor during long periods of inactivity.
Tools Required
Ensure the following tools are prepared before starting. Losing small parts during cleaning can be costly and frustrating:
- Phillips screwdriver: For removing the fuel bowl.
- Flathead screwdriver: For removing the main and pilot jets.
- Hex key: Needed for carburetors with hex screws.
- Metal wire: For cleaning jet passages.
- Brush: To scrub stubborn residue in the fuel bowl.
- Wrench: For removing components like the main jet if they are hex-shaped.
- Carburetor cleaner: Essential for dissolving grime and varnish.
Safety Precautions
Before we go into detail about how to clean a carburetor, let's talk about safety. It's not the sexiest topic, but trust me, it's very important. We are working with chemicals and some flammable parts, so taking the right precautions is key.
Make sure flammable materials are kept as far away from open flames or sparks as possible. You're not a “human torch," and getting burned is no fun. This means that you can't have smoking or lit candles around when you're working with them. Being fire safe can really keep your eyebrows intact!
Also, do this in a well-ventilated, airy place. It will help avoid inhaling toxic fumes that can cause discomfort.
Next up are the cleaning products you are using. They are not all the same. It's really important to read the labels. Some of these products have specific instructions that you need to follow to ensure safety. If there are any warnings, pay attention to them! Speaking of chemicals, some of them can be pretty strong. We're referring to the types that you may need gloves or even a respirator to handle. Be sure to know what you're dealing with and use the right gear to protect yourself.
Another important issue is what to do with used cleaning solutions and materials. You cannot pour these down the sink. Follow local regulations about disposal so the planet smiles and stays safe. It's not just about us; we have to do our part to protect everything around us.
To keep your eyes safe from the cleaning solution, we recommend wearing goggles. It's a simple way to protect yourself while you work! And please bring gloves. All cleaning agents are somewhat corrosive and damaging to the skin. It sounds expanded, but just look at some mechanics' hands. They often ignore safety measures and it's a problem that gets overlooked.
How to clean a carburetor
Finally getting to the point, allow me to say a few more words before I officially start. Let me describe the whole process in one paragraph, which will give you a clear idea of the whole process. This will give you a clear idea of the whole process. It will help you follow the steps below with a better understanding and judgment.
Shut off the fuel valve to empty the carburetor float chamber. Remove the carburetor using appropriate tools. Disassemble it carefully, then thoroughly clean both exterior and interior surfaces. Reassemble the components precisely, ensuring each part returns to its original position. Finally, reinstall the carburetor securely in its designated place on the engine.
Ok, details; please scroll down!
Removing the Carburetor from the Vehicle or Equipment
1. Close the fuel valve
Many tutorials and videos teach you to remove the carburetor. But they don't mention closing the fuel valve first. If you remove it without thinking, congratulations. You now have a floor of gasoline and gasoline-smelling air.
2. Remove gasoline from the carburetor float chamber
All carburetors have a drain tube at the bottom. Use a screwdriver or wrench to open the drain screw. This will drain the fuel from the float chamber.
3. Removing the carburetor
If the carburetor is fixed with rubber boots, use a Phillips screwdriver to loosen the clamps. Then, grasp the side of the carburetor to remove it. If the carburetor is held in place by a flange, use a wrench to remove the screw to take out the carburetor.
4. Remove the throttle cable
There are usually two ways to connect the throttle cable to the carburetor. One is through the top cover to catch the slider. The other is a side pull type carburetor. The side pull carburetor is easier to remove the cable. The slot is exposed. You can remove the cable directly by following the slot.
The other type of carburetor requires you to open the top cover first. Then, lift the part of the top cover to the carburetor slider along the throttle cable. Next, compress the spring with one hand. Grab the end of the throttle cable. Finally, remove the cable by following the slot of the slider.
Removing the Carburetor
1. Remove the idle screw
Take care to mark the location of the idle screw threads with a marker!
The idle screw is usually visible on the carburetor's side. You can remove it with a flathead screwdriver.
2. Remove the air screw
Remember to tighten the screw clockwise for the total number of turns. Then, reassemble the screw by the same number of turns to restore its original position.
The air screw is harder to find than the idle screw. It is usually located on the air intake side or the fuel intake side. The air screw can be removed with a screwdriver.
3. Remove the lower carburetor cover
Use a Phillips screwdriver (or hex key) to unscrew the bolts. If the carburetor is very dirty and hasn't been cleaned for years, gently pry it open with a Phillips screwdriver in the crevice. Be careful not to use too much force when opening the float chamber. Some models have a drain tube in the lower carburetor cover. You need to adjust it to remove the cover.
4. Remove the float
The float connection is fixed with a float pin, you need to use a small wire to push out the float pin to remove the float and float valve.
5. Remove the main jet and slow plane
Normal carburetors only need one screwdriver to remove the main jet and slow plane. But, if it is a PWK carburetor, a hexagonal screw is used for the main jet, so you need to use a wrench to remove it.
6. Remove the Needle Jet Holder and Needle Jet
The Needle Jet Holder is attached to the main jet and can be removed with a wrench. The Needle Jet needs to be removed by pushing your finger in the venturi and coming down the pipe.
To begin cleaning the carburetor
1. Clean all visible surface dirt
If you have time, soak all parts in cleaner for 1-20 hours to soften the dirt and make it easier to clean. After soaking surface dirt with a brush.
2. Cleaning the idle screw and air screw passages
When cleaning the channel opening, first spray a cleaning agent inside to soften the dirt. Then, use a wire brush. You can spray the cleaning agent repeatedly to wash out the dirt. Condition can use compressed air on the channel stamping.
3. Clean the lower cover of the carburetor
The lower cover needs cleaning. The brush should be scrubbed until there is no dirt.
4. Clean the float valve channel
The carburetor leaks oil; pay special attention to this position. A blockage from anything as small as a hair strand will prevent the float valve from closing tightly. This will cause oil to leak. Older carburetors need to be checked for the float valve gaskets. If they are worn or aging, replace them.
5. Clean the main jet and slow down airplanes
First, spray the main jet and slow planes with cleaner to soften the dirt. Then, use a wire to remove the dirt from the channel. Finally, rinse with cleaner several times.
6. Cleaning the Needle Jet Holder and Needle Jet
Cleaning the Needle Jet Holder and Needle Jet is the same as cleaning the main jet. Use a wire and detergent, repeatedly.
Assembling the Carburetor
Install the Needle Jet, Needle Jet Holder, Main Jet, and Slow Plane in that order.
Insert Float, Valve, and Pin into carburetor. Pivot float horizontally many times. Check for smooth, unhindered movement throughout the full range of motion.
Finally, put the lower carburetor cover on and the idle screw and air screw back in place.
Installing the Carburetor
After assembling the carburetor, reinstall it to the motorcycle. But, check the rubber boots for aging signs before installing it.
Connecting the Throttle Cable
The throttle cable passes through, in order: the top cover rubber, the top cover, the spring, and the spring spacer.
Compress the spring with one hand and snap the end of the throttle cable into the slider slot.
Finally, put the slider into the carburetor to tighten the top cover, or use a screwdriver to secure the bolt.
Connecting the engine
Begin by linking the carburetor's air filter side to the manifold. If no filter box exists, attach the carburetor directly. Next, join the air intake's rubber boot, securing it with a wrench on the flange port. Finish by tightening the clamp using a Phillips screwdriver.
2. Connect the fuel pipe, open the fuel valve, and observe whether there is any fuel leakage.
3. Start the engine (open the choke if it doesn't start)
Conclusion
Does it feel very simple after reading the cleaning steps? With the right tools and hands, you can clean out the grime like a pro.
We covered the why and how of cleaning your carburetor. It will keep your engine “gurgling” and give you a smoother ride.
Are the tools ready? Very well! Follow the steps, be safe, and remember: regular cleaning keeps your carburetor in tip-top shape. It just takes persistence and care.
You can't stop there. Get your hands dirty. Get into it, enjoy the process, and feel the difference in your ride. Have questions or need more tips? Meet others, share your story, and continue to be educated. Your engine deserves the best, and so do you. Let's keep the wheels turning together!
Frequently Asked Questions
How often should I clean my carburetor?
Clean it every 3,000 miles or once a year, whichever comes first. Regular cleaning prevents buildup and maintains engine efficiency.
What safety precautions should I take?
Choose an area where air circulation is maintained, and it is a good idea to wear goggles and gloves. It is prohibited to allow open flames to get close enough to start a fire on the way.
How can I tell if my carburetor needs cleaning?
- The engine is difficult to start or requires many attempts to start
- Poor acceleration and sluggish acceleration
- Unstable idle or engine stalls easily
- Black smoke from the exhaust (indicates an excessive fuel mixture)
- Fuel efficiency is significantly reduced, and fuel consumption increases
- Engine misfires or wheezes
- Carburetor leakage
- Lack of engine power, especially under load
- Visible dirt or residue on the exterior of the carburetor
Can I clean the carburetor myself?
Isn't that what I'm writing this article about? It's so simple that you can clean the carburetor yourself if you have all the tools.
I recommend taking photos of each step to prevent forgetfulness. Also, use a small box to sort and store the tiny parts. This will prevent them from being lost.
What happens if you do not clean the carburetor?
It can cause performance issues, raise fuel use, and damage the engine. Regular cleaning is very important for a good working carburetor.
What is the best way to clean a carburetor?
If you ignore the cost, you can use ultrasonic cleaning. But, the mechanic usually disassembles the carburetor and brushes off the dirt with a cleaning agent.
Can I clean the carburetor without disassembling it?
Yes, as long as there is enough space under the carburetor to open the lower cover.
What are the symptoms of a dirty carburetor?
- Difficulty starting the engine or many attempts to start it
- Poor acceleration, slow acceleration
- Unstable idle or engine stalls easily
- Black smoke from the exhaust pipe (indicating over-mixing of fuel)
- Significant decrease in fuel efficiency and increase in fuel consumption
- Engine misfires or wheezes
- Carburetor leakage
- Lack of engine power, especially under load
- Visible dirt or residue on the carburetor.
Can I use WD-40 to clean the carburetor?
WD-40 is a water displacer and a lightweight lubricant that does not clean well. It is not recommended as a replacement for carburetor cleaner.
Carburetor Cleaner dissolves carbon, varnish, and other residues in carburetors. WD-40 will not remove these deposits.
