Carburetors play a critical role in traditional combustion engines, and the motors that power some of our favorite power tools are no exception. Of course, with time, maintenance of this part is important to ensure your machine’s smooth and efficient operation.
It is not possible currently to buy a carburetor adjustment tool at Harbor Freight. They don’t carry them seemingly for the same liability concerns that many stores and online retailers have. Due to legality issues, it is difficult to find them unless you search one mega online retailer, Amazon.
Adjustment is one of the key aspects of carburetor maintenance and today we will be discussing the importance of carburetor adjustment tools, as well as where you can source them. We will also briefly touch on the legality of selling and distributing carburetor adjustment tools.
Let’s get started!
Can you adjust a mower carburetor without a tool?
Most vehicles and power tools that have combustion motors make use of a carburetor to facilitate the combustion process.
Lawnmowers are no exception.
A lawn mower carburetor can be adjusted without a specifically designed tool, but having a simple screwdriver is important. Along with carburetor cleaner and a pair of gloves, this simple tool can be used to adjust choke linkage, high-speed mixture, and idling speed.
The carburetor is responsible for receiving the air and fuel needed for combustion and channeling them towards the combustion chamber in the engine cylinder. Air comes in from the air inlets and via the air filter. The quantity of air taken in depends on the machine’s choke setting.
“Choke” is a way of controlling the volume of air that comes into the intake manifold. In simpler terms, the choke allows you to tweak your fuel/air ratio. Closing the choke increases the amount of fuel in the ratio, which facilitates a rich supply of fuel to the combustion chamber for easier cold starts.
Opening up the choke lets more air in, supplying oxygen required for the fuel in the combustion chamber to explode and produce power.
Fuel comes into the carburetor from the fuel tank. Fuel is sucked into the carburetor by a vacuum that is created when air is passed through it. Fuel is delivered to the carburetor in just enough quantities for efficient combustion to take place. Any extra fuel that comes into the carburetor is caught in a float bowl attached to its base.
The float bowl is there to protect the carburetor from getting flooded. The bowl houses a piece of plastic known as a “float” that holds a metal needle lined up towards a fuel flow channel. When the fuel fills up the bowl, the float…er, floats upwards and pushes the needle towards the channel to block it.
So, in a nutshell, a normally-functioning carburetor delivers air and fuel to the engine as and when needed to ensure optimum performance levels.
Of course, as we all know, parts are not always going to be functioning properly. This is especially true for your mower’s carburetor, which is pretty much a moving part.
Faulty carburetors are often at the heart of many a lawnmower problem. Starting problems, loss of fuel efficiency, dark smoke from the exhausts, as well as noticeable power loss and surging are just a handful of the issues that can signal a problematic carburetor.
Most small engine experts will tell you that the number one root cause for these problems is the build-up of dirt and debris in the carburetor. A lot of this gunk comes from the air and from the fuel itself.
You see, gasoline contains several particulates that can build up over time. Low octane gasoline is more likely to have this problem. With time, the gunk can accumulate along inlet or outlet valves, effectively restricting fuel delivery to the chamber…which means weaker combustion if any.
Dirty or damaged air filters can also let airborne particulates through to the carburetor, which can cause the same problem.
Wear and tear
Apart from debris, carburetors can also fall victim to good old wear and tear. Corrosion, loosening of screws and bolts, as well as the wear of sealing rings can hurt performance.
So, with all of these potential problems, one needs to always be ready to make some corrective (or preventative) tweaks.
Aside from routine maintenance and repairs, there are a few performance adjustments you can make if you feel that you could be getting more from your carburetor. Each adjustment requires the use of a screwdriver, carburetor cleaner (Amazon link), and a pair of gloves. We highly recommend cleaning the carburetor before you work on it.
The first adjustment governs the idling speed.
After accessing the carburetor (which may require the removal of your air filter and its cartridge), you must locate the idle adjustment screw. This screw is normally found on the primary linkage. The purpose of the screw is to regulate the most efficient fuel-flow vacuum possible at idling speeds. With use, the screw may be shaken up and dislodged from this optimum position.
The adjustment is fairly simple. All you have to do is tighten the screw in its place as you would a regular screw. Next, you must unscrew (one and a half turns) the screw from that new position and into the optimum idling position.
You can then do the same thing for the main jet adjustment screw at the bottom of the carburetor float bowl. Screw it to its tightest, and unscrew by about one and a half turns. You should then run the engine and listen for normal idling.
The next adjustment is for the choke linkage.
Again, you might have to take out your air filter cartridges, particularly if you’re working on a riding mower. If your mower has a throttle or variable speed control, you should engage the highest setting.
Next, use a screwdriver to detach the screw holding the bracket on the throttle end of the casing. You don’t have to remove the screw completely for this.
You should then push and pull the throttle cable with your hands until you see the choke plate on the other side of the carburetor close. While holding the cable in this position, quickly screw the bracket back in place. A quick test will reveal that upping the throttle closes the plate while reducing the throttle opens it up.
The final adjustment is for the high-speed mixture.
This requires you to work on the high-speed adjustment screw, which is usually on the opposite end of the idle screw. Please note that some carburetors may not have this screw at all.
Begin by running the engine for a few minutes to get it warmed up. Next, shut off the engine and screw the high-speed screw tightly in place before unscrewing it by one and a quarter turns.
Next, set your throttle or speed control to the highest setting and start the engine again. At this point, screw the high-speed screw in until the engine noticeably slows. Once this happens, unscrew the screw until the engine slows down once more. The middle point between these two points (i.e., where idling is at its fastest and smoothest) is the sweet spot you are looking for.
As you can see, adjustment can be done with a regular screwdriver and some good old elbow grease.
A carburetor adjustment tool
However, some special tools can help you get the job done more efficiently. These are known simply as carburetor adjustment tools.
Now, of course, one would think that it would be easy to just hop onto the Harbor Freight website and peruse through the various options. However, a quick search on the site reveals that the pickings are slim. In fact, there are NO carburetor adjustment tools listed on Harbor Freight for reasons we will discuss shortly.
Luckily though, you can always count on Amazon. The online retail giant has several options for you, including TOPEMAI’s 10-piece carburetor adjustment tool screwdriver kit for 2-cycle engines. Unfortunately, even these tools come with a catch…
Is it illegal to sell a carburetor adjustment tool?
Well, yes…and no.
It is not legal to aid someone in altering emissions or sell instruments with the sole purpose of skirting codes set by government agencies. Carburetor adjustment tools could be labeled ‘defeat devices’, leaving those selling them open to legal ramifications.
You see, the Environmental Protection Agency (EPA) is the governing authority on emission regulations in the United States. Power tools and vehicles need to satisfy all relevant codes before they are rolled onto the consumer markets.
Our particular focus today is on the US Code of Federal Regulations, Title 40: Protection of Environment CFR 1068.101 (b) (2), which talks about “defeat devices”. It is not legal to make, sell, or install these defeating devices unless there are special cases for doing so.
According to the code itself, a defeating device is “any component that bypasses, impairs, defeats, or disables the control of emissions of any regulated pollutant, except as explicitly allowed by the standard-setting part.”
Violations may be subject to fines of more than $4,000 for each violating component.
Unfortunately, carburetor adjustment tools fall under the definition of a defeat device since they are specifically made for tweaking carburetors that ought to be in line with emissions standards from the factory. The EPA regards this as a potential avenue for aftermarket bypassing of its codes.
In simple English, it is not legal to sell or market these tools to the general public. Those who wish to acquire these tools must be licensed specialist technicians otherwise the seller may face penalties.
This is why you won’t find a carburetor adjustment tool on Harbor Freight. Even Amazon won’t sell you these tools unless you provide proof of your certification.
Final Touches On Harbor Freight Carburetor Adjustment Tools…
Though there are no current offerings at Harbor Freight for an adjustment tool for your mower’s carburetor, that is not to say you are out of luck. If your heart is set on getting a tool or an assortment of them, then Amazon’s offerings may fill your need.
Though, for the vast majority of issues that you can address yourself on your mower’s carburetor, all that is really needed is a screw driver, some carburetor cleaner, and a bit of elbow grease.