In many parts of the world, ATVs are required to be fitted with a spark arrestor (spark arrester), either by law or by local regulations. But what is a spark arrestor and what is its purpose? Does it have any disadvantages? Can you safely remove it? How do you remove it? How do you clean it when clogged? We take a quick look at all these questions in this article.
The purpose of having a spark arrestor on an ATV is preventing wildfires by trapping any glowing particles from the engine itself or carbon deposits that break free before they exit the tailpipe. Besides the advantage of preventing a wildfire, spark arrestors come with some other advantages or disadvantages, depending on how you look at it.
How to know if your bike is fitted with a spark arrestor
Not all ATVs are fitted with a spark arrestor. To check if your bike is fitted with one, you simply have to take a look into the rear end of your exhaust muffler, because this is where it will be located if you have one.
On many mufflers, it is written on the outside whether an arrestor is installed or not. On others, you have to physically see if there is one.
Use a flashlight if the arrestor is not located in the very end of the muffler. What you are looking for is a fine steel mesh screen that covers the whole inside diameter of the exhaust. It could be shaped like a tube or just like a plane screen.
If the screen is shaped like a tube it can be harder to see it from the outside. Use a screwdriver to gently “feel” if there is a screen there. It should look something like this:
Although not as common as screen style spark arrestors, some mufflers are fitted with a set of discs witch the exhaust need to pass through. These are usually fitted at the very end of the muffler and should be easily observed.
Some early ATVs were fitted with a centrifugal style spark arrestor, but this is not very common today. These could not be removed, but sometimes had inserts for back pressure tuning.
Do you really need it?
If your ATV does not have a spark arrestor there is a chance that small particles from the engine itself will exit through the exhaust like a glowing red spark. With today’s modern production technologies tho, production of particles from the engine itself is not a common problem anymore.
However, over time, carbon deposits can build up on the inside of your engine. Eventually, these deposits may break free and turn into a glowing red spark on its way out the exhaust.
You may have seen this if you ever been riding behind a bike without a spark arrestor installed at night time.
And yes, these sparks may cause a wildfire under the right circumstances.
The laws governing spark arrester use depends on where you are riding. In the US there is a good chance you are required to have a certified and undamaged spark arrestor installed whenever you are riding on federally, state or locally managed land.
It is always a good idea to check the requirements for your area before you head out to the trails.
But one thing is certain: Using a spark arrestor is always a good idea no matter where in the world you are riding where a spark could impose a potential fire hazard.
So how does a spark arrestor work?
A spark arrestor is designed to trap any glowing sparks before they exit your tailpipe by acting like a filter.
On a screen-style spark arrestor, the mesh creates many tiny holes witch the exhaust needs to flow through. Any particles larger than the holes in the mesh will be stopped. Screen arrestors come in different ratings depending on how fine a mesh is used.
A disc style arrestor has the same effect. Many small discs are placed together with a small spacing to stop any particles from passing through.
Potential advantages or disadvantages of using a spark arrestor
Many are looking into removing their spark arrestor because of the potential power gains.
While its true that the arrestor to a small degree will restrict the airflow that goes through the exhaust system, removing it is not equivalent with more horsepower.
The effect of removing it will depend entirely on how your quad is built and tuned. Variables like jetting, intake, elevation, cams, exhaust system design etc will impact the results.
Removing it may or may not result in a improved performance. You won’t know for sure until you have given it a try.
On some ATVs, you may even experience a small drop in power when you remove the spark arrestor. The reduced backpressure you get by removing it will on some systems result in decreased performance.
If you are lucky, and your systems react favorably to removing the arrestor, you are looking at potential top-end power gain in the range of 1 horse-power. Ironically, the reduced backpressure may at the same time give you just as much of a drop in low range power and torque.
If better performance is your end goal, I recommend you keep the spark arrestor installed until you can afford to get a quality aftermarket exhaust system (also with a spark arrestor), and a re-mapping of the engine. This could give you a significantly more noticeable increase in power compared to only removing the spark arrestor in an OEM system.
Installing a spark arrestor will result in a decrease of the sound level of your system. Generally by a couple of dB.
Some riders love a louder and deeper sounding system and want to remove the arrestor to achieve this.
Others prefer their quads, and co-riders quads, to be more silent and “discrete”.
While I’m not trying to be the moral police here, its worth mentioning that engine noise is the most common reason why people complain about any type of off-road riding. And with complaints comes restrictions for the use of tracks and trails. That’s just how it is.
So be aware, if you ride somewhere noise can be an issue, you may risk ruining for yourself and other riders.
Some people think having spark arrestors on their quads is downright ugly and want to remove it for this reason only.
While I can agree design was probably not the top priority when many spark arrestors were designed, I will leave it up to you to decide if this is big enough of an issue for you to remove it.
Removing the spark arrestor
Most spark arrestors can be removed from the muffler, some way or another. The procedure you need to follow to achieve this differs from model to model.
Usually, all you need to do is to remove the bolts or drill out the blind rivets holding the arrestor in place, and it should just pop right out.
On some systems, it may require some more work and you risk ruining the arrestor itself in the removal process.
What you need to remember is when removing the spark arrestor is that your engine may be running a bit leaner than it did before due to the change in air/fuel ratio.
The air/fuel ratio is determined by your bikes jetting setup, which can be altered to your specific need. So you need to make sure you are still within the recommended tolerances after removing the arrestor. Consult a mechanic if you are not sure how to do this.
On many ATV you can safely remove the spark arrestor, or even install an aftermarket exhaust system without having to make alterations to your jetting because they are normally set up to run a bit rich from the factory, but this is no general rule!
If you are unlucky, having your bike running too lean can over time result in damage to your engine. To be on the safe side you should have your air/fuel ratio controlled by a professional any time you make alterations to your exhaust system.
Cleaning a clogged spark arrestor
After some time of riding, trapped carbon particles will build up in your spark arrestor so it will need cleaning for your bike to be performing as it should.
A clogged up arrestor may result in a significant decrease of power because of blocking of exhaust flow. This applies to both disks an screen style arrestors.
The user manual usually states that the arrestor should be routinely cleaned after running a certain amount of miles.
Usually, the arrestor is relatively easily removed for proper manual cleaning, or the muffler is equipped with some type of cleanout plug to make accessing and cleaning fast and easy.
For a disc style arrestor, you need to disassemble and clean each disc individually.
One way to clean the parts is by using some fuel and a copper wire brush to scrub off any debris. Rinse in fuel and wipe clean with a rag. Let all the parts it air dry before you re-install the assembly into the muffler.
However, the above method will work just fine, but it can be a bit time-consuming.
For screen style spark arrestors the easiest way to clean it is by using a blow torch to burn the carbon away.
This can be done after you have removed the screen from the muffler, or if it is easily accessible from the rear of the muffler you can even burn away the carbon with the screen still installed in the muffler.
If you use this method, always make sure you use safety glasses and don’t put the torch against anything that can catch on fire, like your bikes plastic fenders!