Introduction: Cleaning a Carburetor in 8 Easy Steps!
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.
Tools needed: Phillips screwdriverFlat screwdriverNeedle nose pliersWire brushWrenches or socket set
Supplies needed:Carb and choke cleanerCarburetor 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.
How Does a Carburetor Work?
Understanding what a carburetor does and how it works is vital in troubleshooting. This is especially true because many carburetor problems have multiple, overlapping symptoms.
The carburetor’s role is to provide the space where gas and air mix. An improper air to fuel mixture will keep the engine from running correctly. An incorrect gas and air mix cause most carburetor problems. Your job is to figure out what is causing the mix to be off.
Mower Speed Problems
If the engine speed does not increase, the speed is unstable, or the engine performs poorly at high speed, then an additional clog to check for is the pilot jet—either its air path or the jet itself are clogged.
Should speed problems happen at low speeds or the idle speed is unstable, then in all likelihood, the pilot jet or its air path is clogged. You will need to check for dirt and clean.
Copyright protected content owner: ReadyToDIY.com and was initially posted on 2020-08-27.
Getting to the Mower’s Carburetor
Before you get started, we recommend you disconnect the spark plug cap. This is to prevent the mower from accidentally starting. Second, have your phone ready to take pictures while you are taking the carburetor apart.
Fix Without Taking the Carburetor Apart
You might get lucky and avoid having to take the carburetor apart. To do so, FOCUS on cleaning out the carburetor idle jet. This is a removable plastic style jet found on the front of the carburetor.
Final Thoughts
Carburetors are an essential and often overlooked part of a lawn mower. If your mower is not running well and you have checked the air filter and spark plug, you might have to work on the carburetor. Taking the carburetor apart and cleaning it is time-consuming but not difficult. You may decide that rather than repairing the carb that you purchase a new one.
ReadyToDIY is the owner of this article. This post was published on 2020-08-27.
Honda lawn mower carburetor cleaning
Motor won’t idle, so I’m cleaning the carburetor with attention to the idle jet and the small openings just inside the throat near the throttle butterfly. After removing the idle jet I can spray carb cleaner into that opening and I get a nice spray of cleaner out of the first tiny hole into the throat, the one that is located just outside the area where the butterfly closes. My question, there are three additional small holes just inside the butterfly and I can’t get any spray to exit from those holes.
I thought when I did this a year ago, that I was able to see the spray coming out of those three holes when I blocked the first, outer hole with my finger. I have been able to get a very small guitar string wire into the three inner holes but still nothing to spray out.
Anyone know if I should be seeing the cleaner spray from those three inner holes or if there is another location other than the idle jet, on the carb to enter the carb cleaner spray?
The three little holes are transition ports and the Idle mixture. The Idle mixture screw has a limit cap unless someone took it off. The cap can be removed if you heat it with a mini torch and gently pull it off. There is a slot head screw under the cap. Do not try it without heating as it is designed to break off. Unscrew the mixture screw and then you can shoot some carb cleaner in there and it will (should) come out the bigger of the transition ports. Best to take the carb off and apart and make sure all the jets are clear.
Will Muffin Lucy the dog
“Yes, well. perhaps some more wine” (Julia Child)
Thanks Will, sounds like you know about this. I saw the little cap, looks like aluminum, just under those three holes. But if there is a screw under there that is designed to break off I don’t think I will mess with it unless as a last resort.
The carb cleaner is in a pressurized spray can. Do you think that I should see some carb cleaner exiting from one or more of those transition holes, if I can insert the carb cleaner pressure tube into the right place on the carb body and can plug up any other points of exit?
There is a brass idle mixture adjustment screw on the side of the carb, not under any cap. Is the screw under the aluminum cap used to adjust mixture in the transition zone?
Doug S/V Gypsy Soul presently in Chula Vista CA
Doug, the mixture screw that feeds the idle is under the “aluminum” cap. In order to clean it out you must remove it and unscrew the mixture screw. I use an Ancor mini torch that is often used on heat shrink connectors. The cap is glued on with heat sensitive Loctite. To reset it. carefully turn the screw in until it stops. I believe the factory setting is 1.75 turns out. However 2 turns out will richen the mixture slightly and improve the idle.
That carb is a pretty complicated item compared to others. You might want to have the dealer clean it for you.
Will Muffin Lucy the dog
“Yes, well. perhaps some more wine” (Julia Child)
OK now it is more clear. I don’t have a minitorch. for heat shrink I use a heat gun but the minitorch sounds useful for this and other things too. I have only a larger torch that would probably destroy something if used on this.
Anyway I did clean this carb out last year and motor was running great until recently when it got some goop in the gas tank. yes its a bit complicated but very well engineered unit as far as I can tell. If motor won’t idle tomorrow I’ll take the carb to a shop.
This is a known problem with these outboards. Having dealt with it many times here’s what I’ve learned. Honda only recommends sonic cleaning the dealer will charge more to clean it than to install a new carburetor costs. In fact our dealer will no longer clean them because it often doesn’t work. The most common problem is the main nozzle (12). You can try to clean it but I’ve never been successful the dealer that I’ve taken them to has never been successful. It’s best just to buy a replacement install it yourself. After you take these things apart a few times it’s pretty easy. If the nozzle doesn’t work I’d buy a new carburetor. After you get this fixed I’d recommend nonethanol fuel, stabil running the carburetor dry if it’s not going to be used for more than a day.
How to Clean a Lawn Mower Carburetor Without Removing It (Yes, It’s Possible)
Removing the carburetor 20-thread bolt using an M10 wrench sounds more like an engineering project than a quick lawn mower repair for a Saturday morning. Carburetors are fairly complex mower parts that annoyingly need attention if you want to keep your lawn mower running smoothly. So, do you have to know a lot about engines and have a tool collection to clean a carburetor? And do you have to remove the carburetor to clean it? Let’s take a look.
Can You Clean a Lawn Mower Carb Without Removing It? (The Short Explanation)
If you’re suffering symptoms of a bad carburetor, you’ve probably come across a lot of people who recommend removing the carburetor to clean it. Even though I say this myself, it’s not the only solution. A carburetor doesn’t need to be stripped down and squeaky clean to work well. So, do you need to remove the carburetor to clean it? No.
There are two methods to cleaning a carburetor while it stays on the lawn mower. The first is a chemical spray clean, and the second is a jet removal clean. So let’s go over how to clean a carburetor without removing it.
Chemical Spray Cleaning
How to Clean a Lawn Mower Carburetor Without Removing It? (Step By Step)
Now that you have seen how to clean a lawn mower carburetor without removing it let’s take a more detailed look at the steps you’ll need to follow.
Step By Step Carburetor Chemical Spray Cleaning
The first step is to remove the cover from the air filter to gain access to the inside of the carburetor. You may find that your cover is secured with a screw, so you’ll need to grab a screwdriver to remove the fastener.
Next, remove the air filter from within the filter housing and set it to one side. If your lawn mower has two filters, you’ll need to remove both of them, including the air filter and pre-filter.
Now, grab your carburetor cleaner and give the outside of the carburetor a good spray. Try to get the cleaner into all the nooks and crannies so that it really gets to work on all the dirt.
Next, use a small nylon brush and start working off all the dirt and grime. I like to use an old toothbrush for this part of the cleaning. Also, don’t be tempted to use any type of metal brush as the carburetor is made of a soft alloy that is pretty delicate. A toothbrush should work just fine.
Once you are happy with the outside of the carb, you can go ahead and start the lawn mower’s engine and set the throttle to a fast idle.
With the engine running, use the same cleaner and give the inside of the carburetor a good spray. A couple of seconds should be enough. Just make sure that you don’t stall the engine. Once the engine has burned off all the cleaner, give the carburetor another spray inside. I like to repeat this a couple of times to make sure it’s getting a good thorough clean.
Next, allow the lawn mower to run for a few minutes after you believe the engine has burned off all the cleaner. This allows any of the cleaner sticking around to burn off completely.
The last job is to reinstall the air filter and replace the air filter cover. If you had to remove a screw for the cover, remember to screw it back in. Also, this is the perfect time to inspect the air filter and make sure it’s not soaking in oil or worn out. You could even clean the air filter before putting them back in.
Finally, switch off the lawn mower or head out and tackle your lawn.
Tools Parts to Spray Clean Your Carburetor
Step By Step Carburetor Jet Cleaning
The first job is to switch off the lawn mower’s fuel if you have a cut-off valve. This will save any unnecessary fuel spillage.
So, start by removing the bolt on the bottom of the carburetor located at the center of the fuel cup. You’ll need a small wrench for this. Now, for some of you guys, this bolt is the actual jet. This means you can skip the next steps until we get to the cleaning part. For you guys that don’t have this type of carburetor, keep following along.
Next, once you have removed the bolt, you should be able to pull the fuel cup off the carburetor. Just be a bit careful, as the cup will probably be full of gasoline.
Now, located where the fuel cup bolt would connect to the inside of the carburetor, you’ll find a screw. Take a screwdriver and remove this retaining screw. Once you take this screw out, the jet should fall out. Some lawn mowers incorporate the jet into the screw, so just take a close look.
Next, it’s cleaning time. So, if you take a look at the jet, you should see a clear hole all the way through it. I find holding it up to the light helps. What you are going to need to do is remove any dirt that is clogging the hole. I find that a thin wire works well enough. Once you have it cleaned out, you can give it a spray of your carb cleaner and wipe off any grime.
Finally, it’s time to put the few bits back on the mower. So the order is the jet, screw, fuel cup, and finally, the bolt. For you guys with just the bolt/jet, pop it back into the mower and tighten it up with your small wrench.
That’s all there is to it. It’s pretty straightforward and takes no time at all. Just don’t forget to turn the fuel back on.
Tools Parts for Carburetor Jet Cleaning
Cleaning a Mower’s Carb: To Remove or To Not Remove
So, we have discussed how to clean a lawn mower carburetor without removing it, but will this solve all your carburetor issues? Well, it depends. You’re going to find that spraying the cleaner directly into the carburetor is going to cure problems from fuel impurities, fuel gum, and bad fuel in your mower. However, a clog in the carburetor jet needs a bit more work, like my jet cleaning method. Also, you’re going to find that some lawn mowers don’t offer enough room to remove the carburetor jet. This means the carb is going to have to come off.
So, if you have a lawn mower like a Yard Machine with a Briggs Statton engine, you’ll probably have to remove the carb, but give the chemical spray a try first.
About Tom Greene
I’ve always had a keen interest in lawn care as long as I can remember. Friends used to call me the “lawn mower guru” (hence the site name), but I’m anything but. I just enjoy cutting my lawn and spending time outdoors. I also love the well-deserved doughnuts and coffee afterward!
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Why is it Important to Clean Your Lawn Mower’s Carburetor?
The carburetor of your lawn mower needs to be kept clean in order for the machine to work as it should.
Think of the carburetor in a car. If it isn’t kept clean and properly maintained, your vehicle will not run properly.
This is the same with a small engine such the kind you have in a lawn mower.
If you are having certain problems with your mower, there is a good chance that you need to clean the carburetor. Below are some signs of a dirty carburetor:
How to Clean a Mower Carburetor Once You Locate It
Let’s take a look at how to clean a lawn mower carburetor.
Removing the Carburetor
What if the Carburetor Needs Repairs?
It is possible that your carburetor will need repair as well as cleaning. If that is the case, you can consider buying a carburetor repair kit. This will help you with replacing some of the major components of the carburetor, such as the diaphragms, gaskets, float, and float needles. You can probably find a kit that matches your mower on Amazon for less than 20.
If you find that the carburetor continues to have poor performance, it’s possible that you will have to get a new carburetor and replace the old one. The price of a replacement carburetor will typically be about 50, and you can find genuine manufacturer’s carb replacements on Amazon (like this one for a Honda self-propelled mower).
If you’re sure your lawn mower issues are the result of carburetor problems, it’s generally easier to buy a new carb and replacing the whole thing vs attempting to repair a few gaskets or parts.
In my experience a repair kit works better in theory than in practice, and your average weekend warrior is better off replacing the whole thing if determined to DIY a fix. For 30 more, why not install a brand new carb?
The other option (recommended for most people) is to take your mower to a small engine repair shop and let them do the work for you. This is less expensive than you’d think, and will save you some time and headaches.
For optimal lawn mower maintenance, you should clean the carburetor every year.
This will help your mower always perform at the optimal level and help to hold off problems that will require parts replacement or full replacement of the carburetor.
And you don’t have to take your carb out to keep it running like new – I give my mower a shot of Gumout Carb and Choke Cleaner (Amazon link) before every mow to keep it running like new. It’s like 5 a can and lasts a whole season.
Maintain Your Lawn Mower So It Lasts!
Understanding how your lawn mower works and how to maintain it is key to making it last.
Purchasing a new lawn mower is an investment, so it’s well worth taking the time to read the manual and understand all the components and their functions.
Why small engine carburetor cleanliness is so important
Carburetors play a vital role in the performance of any combustion engine, so small engine owners should take the time to appreciate common carburetor problems and solutions before more expensive issues arise.
The role of a carburetor is to regulate the intake of fuel into an engine while simultaneously mixing it with the correct quantity of air for optimal engine performance. There are two main types of carburetors
Float Type. Used mainly on stationary engine, and typically located below the fuel source, as gravity is relied upon for fuel delivery. Standard lawn mowers typically feature this type of carburetor
Diaphram Type. Used more on most handheld equipment like chainsaws, brushcutters, hedge trimmers, blowers etc. This common kind of simple carburetor is generally mounted above the fuel tank and has no fuel bowl or float. Vacuum pressure is used to draw fuel into the assembly.
The best way to understand the operation of carburetors is to think of them primarily as air pumps. For instance. when you power up the throttle, you are not pumping more fuel into an engine. on the contrary, you are really ramping up the air intake into the system, which then increases the fuel inflow and dynamics accordingly. As such, a carburetor is essentially dependent on two dominant features to work properly. ie. a clean, uninterrupted air intake. plus a clean, uninterrupted liquid fuel intake. yes the word clean is there for a reason. If either the air or fuel intake mechanisms are dirty or impaired, a number of problems may become apparent. The engine :
- Wont start at all
- Takes a large number of attempts to start
- Surges, even at idle
- Performs differently at high or low revs
- Leaks fuel
- Cuts out at idle
When it comes to substandard cleanliness, one of the most obvious culprits is dirty fuel. This happens frequently in cases where an owner leaves a fuel tank full and then doesn’t use the equipment for an extended period of time. In southern states, in particular, this can occur if equipment is used seasonally. There are some cool climates where lawn mowing, for example, comes to a standstill over winter when turf is near dormant, only for activity to resume sharply in mid spring. A chainsaw, similarly, might be used primarily in summer or autumn to allow wood to dry out in time for winter use. In these kinds of cases, fuel can become stale, even worse, the internal parts of the carburetor. including the delicate fuel inlet jet or fuel lines, can become gummed up.
Even if the fuel supply and delivery systems are in peak condition, there are other elements of the carburetor that might be dirty or out of balance, which can lead to sub-optimal performance. The best place to start is to watch and listen to the engine and identify telltale signs that something is out out of kilter. A good place to start is the spark plug, which can reveal a lot about how an engine is operating. If the spark plug end is a coffee colour, then its running fine, a ghostly white means its running lean or sooty black means its running to rich.
The term running lean means less than normal fuel supply is reaching the engine, whereas running rich implies excess fuel is being fed into the system. These levels can be adjusted manually with the mixture adjustment screw, of course but first it pays to ensure all other parts of the carburetor are in good order. It is always advisable to check all basic mechanical systems thoroughly before starting to manipulate factory settings. An added danger is that emissions compliant machinery can easily become non compliant if an owner inadvertently runs a rich mixture. So before tinkering with settings, make sure all parts are clean, undamaged and assembled to correct tolerances.
The obvious first step with cleaning a float carburetor is to unscrew the bowl and give it a good wash and soak using a dedicated carburetor cleaning fluid. Don’t be afraid to leave parts soaking overnight for a really penetrative clean, mindful that less durable plastic bits are like the float itself should not be subjected to prolonged corrosive exposure. Once clean, the float should be able to move up and down unhindered, so be sure to remove every skerick of gunk. Delicate jetter needles, which can easily become blocked, may need extra attention. A good yip is to avoid using old cloths that can leave behind unwanted lint, dust or fabric contaminates. It is far preferable to rinse with water and then use compressed air to blast away any cleaning agent residue and gunk, leaving behind a pristine surface before reassembly. This method works for sand filled fishing reels, and it works for engine parts too. If you aim to carry out your own carburetor maintenance routinely, it is worth investing in a basic toolkit to help maximize the effectiveness of your work.
While a solid cleanout will solve 90% of problems associated with a poor performing carburetor, there is always the chance thats a mechanical fault is to blame for a chronic problem. As mentioned carburetors are essentially pumps, which means leaky seals, split rings and damaged gaskets may need to replaced. Choke and throttle plates may also be bent or damaged due to wear and tear, stress or impact, or they may be in need of screw adjustments.
Taking good care of your carburetor is worth the effort. ignoring a problem can lead to poor fuel efficiency. premature engine were or worse. Carburetor maintenance therefore is crucial to maintaining a smooth running engine.