Removing the spark arrestor relieves back pressure in the exhaust so the engine can move more air through the exhaust. The more air it takes, the more fuel it can burn. Thus, the saw engine uses more fuel and increases horsepower. The effect is from 0% to 40%, depending on the open screen area vs. muffler outlet size/placement.
In this post, you will learn the risks (fire, fine, bugs & more) and benefits(More HP & torque) of removing the spark arrestor screen.
You will also learn how to remove the spark arrestors properly.
… that maximizes the output while minimizing the risks.
These are exactly the same guideline I follow to increase the HP(horsepower) of my chainsaw by 25%-40%…
…while reducing the risks to almost 70%-80%.
And today, I’m going to show you how I did it…
…and how you can do the same thing.
what is Chainsaw Spark Arrestor?
A chainsaw spark arrestor is a screen or mesh that is installed on the exhaust system of a chainsaw to prevent the emission of hot sparks and other potentially flammable particles. It is a crucial safety feature, especially when operating a chainsaw in areas prone to wildfires or other fire hazards.
The main purpose of a spark arrestor is to limit the size of particles, such as carbon or other small debris, that are sometimes found in the exhaust gases of outdoor power equipment2. By reducing the thermal mass of these particles, they are no longer considered a serious fire hazard.
Why Remove Chainsaw Spark Arrestor?
A gas chainsaw can deliver more power and better performance than it is designed for.
You can modify the gas saw for more horsepower for demanding tasks.
That’s one of the main reasons professional chainsaw operators prefer gas chainsaws to electric and battery-operated chainsaws.
There are tons of ways to modify a gas saw.
In this post, I will talk about removing the spark arrestor method, its outcomes, risks, and benefits.
What does a spark arrestor do?
As the name suggests, the spark arrestor arrests/prevents sparks from coming out of the saw muffler. A spark arrestor can do the below tasks.
- Prevent igniting the dry woods.
- Work as a filter to keep stinkbugs and mud dobbers out of the engine.
- Stops getting saw dirt from sucked back into the engine
Having a spark arrestor in a chainsaw is a must in the USA.
However, there is no such obligation in European countries.
You can remove it for cutting at home or garden without any restriction by law, but you must use it to cut on any state or federal land.
You can see very small sparks from the exhaust when operating the saw in a dark environment, such as at night or in the evening.
However, the chance of igniting a fire is very low.
The spark arrestor also works to prevent bugs from getting into the engine.
You may notice a lot of stinkbugs in chainsaws or other power tools.
This happens if you store your tools for a few days.
Sometimes, this may happen overnight, depending on your climate.
Apart from the live bugs, it also prevents saw dirt which can be a problem for your saw later.
How To Remove Spark Arrestor
After arrestor removal, the saw may sound like it is running faster. You can strip the baffles for a boost.
People remove spark arrestors to let it work hard and increase its performance.
The removal of spark arrestor can effect chain speed RPM(Rate Per Minute) or tuning.
Expert operators can experience the differences easily.
I strongly suggest to check and adjust carb before start or resume cutting.
How does It Increase The Performance?
The whole thing is not rocket science. It is simple to understand and implement.
The gas chainsaw has 2-stroke engine. It need back pressure for performing correctly.
Reworking the muffler such as removing spark arrestor relieves back pressure in the exhaust.
After that, the engine can move more air through the exhaust.
The more air it requires, the more fuel it can burn.
Engines take fuel to make power. Thus, the saw engine uses more fuel and increase horse power.
The effect on exhaust flow is from 0 to 40%. It depends on the open screen area vs muffler outlet size/placement.
The outlet hole on a stock muffler is recessed and the screen covers a larger area above the opening.
So, the reduction in flow is very less.
Tip: A Stihl spark screen has an open area equal to 25% of screen area.
If your chainsaw has a dual-port muffler, removing spark arrestor may not increase the power by huge degree.
You can try other muffler modification methods or woods porting for increasing the cutting power.
Benefits Of Removing
Removing the spark arrestor screen can provide a good number of benefits immediately and in the future.
- Better exhaust flow
- Increase engine Horsepower(HP)
- Will run better and leaner
- No need to clean or worry about clogged screen
I removed the screen arrestor screen from my 372xp Husqvarna and twist the exhaust hole.
I now experience the Horsepower is increased a bit and the saw run leaner than it did earlier.
Risks After Removing
The main risk of removing spark arrestor screen is the possibility that it can start a fire.
Starting a fire by chainsaw sparks depends on climate and humidity.
There is an internal baffle that would help with flames. So, the risk is not so high.
In the USA, you cannot run a chainsaw without arrestor on state lands. Doing so will result in huge fine.
If you remove it, ensure you are not in state lands. The US forest service will fine you if they can catch you.
The fine can be as much as a Stihl MS660 (around $3000)
The same goes for the modified quad too.
I know a guy who was fined $6 million for starting a fire in the forest with his modified bike.
In short, if the USFS(United States Forest Service) find you, they would cite you.
If you start a fire, you have to pay the bill. It can make you bankrupt in a single day.
The sparks are very small and are not enough to start a fire in most cases.
The possibility of starting a fire depends on the climate which varies one location to another.
If the weather is hot and dry, the chance is very high. NEVER try to take a chance at that moment.
In Hayfork, California, Nobody runs their chainsaws without arrestors. The fire danger is so high.
Similarly, if you work in a fire zone like the piney wood hills, you must not remove spark arrestors.
On the other hand, it is very hard to start a fire in the forest in northern Ohio with a chainsaw. The climate is not in favor of fire.
Even if you live in the outside USA and have no such rules and regulations, I highly suggest you not to remove it at hot and dry climate.
In short, if there is a slight possibility of starting fire in the woods, don’t remove the arrestors.
Don’t take a chance of catching the woods ablaze.
In a normal climate such as in-home or garden, without much humidity, there is almost no chance of starting a fire.
If you think the exhaust flow is restricted too much for the spark arrestor, you can remove it.
Keep in mind to add it if you go to cut in state lands later.
The other risk associated with removing spark arrestors is getting crap inside the muffler/cylinder.
Without the arrestors, you can experience bugs and mud dobbers living inside your saw engine when you keep them in storage.
For most homeowners, I don’t think it worth to take the risks.
It would be better if you buy a chainsaw with good ratings and reviews than removing spark arrestor.
Should I take the risks?
Govt. Lands or Dry Climate
What’s your climate?
If the humidity is high and dry, there is a high chance of fire. Obiviously, it does not worth to start a big fire in the woods.
Apart from these, if you are living in USA, you cannot remove it in woods and on Govt. property.
So, in short, in this case, I think you should not remove it.
If you cut in a different climate that is not fire-friendly such as wet or damp woods or hardwoods, you can consider removing it.
The same goes if you buck in the shop yard or controlled placed where is no chance of starting fire.
Tip: You can run the saw over gravel can for extra safety measures.
As a homeowner, you will only cut in your home, yard or garden.
Therefore, you may not worry about starting a fire as there is no such possibility.
Since you will never go to be cutting on USFS land, you don’t need the spark arrestor at all.
However, I assume you use a small to medium duty gas saw, so removing the arrestor may not make much difference in power but you can get rid of cleaning the arrestor screen and will never face clogged screen.
Tip: Most of the saws, repair shops get in for service just have a clogged screen.
Tips For removed spark arrestor
Alternatives To Spark Arrestor removal
If you are not comfortable with removing the spark arrestor screen, you can do the below things for performing the screen better.
It also helps to get power.
- Clean spark arrestor from time to time. if the screen is kept clean it doesn’t restrict the flow much
- Some people argue that removing the screen does not make any difference for them. In this case, you can consider doing the muff mod. You can use screen after muff mod.
- Enlarge the internal baffle ports with a screwdriver
- If your saw muffler has a very fine mesh screen, use a less restrictive mesh screen. Some screen is very restrictive. You can replace them with less restrictive ones. You can find them on local hardware store.
- If you use the right gas mix, tune the saw right and use synth. oil, your screen would not clog. So, use right gas/oil mix.
- If you think the screen blocks airflow, just make the exit hole a bit bigger.
- If you feel lack power, buy another chainsaw with desired power.
- You can consider a second exhaust port for better airflow
- In some chainsaw models, the spark screens are much bigger than the outlet. In that case, removing screen will not make any difference.
If you use your chainsaw in the bush for a living, you can consider removing the screen.
Time is money and by increasing the power, you can cut more in less time. You can also consider carbon buildup or Muffler mods.
However, for a homeowner, this is not essential. You can do it for occasional tree felling or logging.
If you own chainsaw like Remington rodeo rm5118r and use it around the house only, you might not need to remove the spark arrestor.
Overall, I can say removing the spark arrestor screen depends on user pref. Bugs can be a problem, fire is not in most cases.