Should You Run a Chainsaw Without a Spark Arrestor?


Spark arrestor screens can be a great annoyance to chainsaw operators everywhere. Spark arrestors are the mesh screens on the exhaust of virtually all modern chainsaws, and they can occasionally get clogged with carbon, greatly affecting chainsaw performance. Predictably, many are tempted to simply throw these easily-removable screens away, but is that really a good idea. Should a chainsaw be run without a spark arrestor? In most cases, the spark arrestor is a crucial safety component designed to prevent forest fires, the consequences of which can be catastrophic. Instead of removing them, it is best to clean or replace these screens regularly. Before we look into why these screens are best left on, let’s look into the purpose they serve and why they can cause problems.

Chainsaw spark arrestor
A typical spark arrestor

The Purpose of a Spark Arrestor

Spark arrestors do exactly what the name implies: They arrest sparks. They are mesh screens placed on the exhaust that catch still-burning pieces of black carbon being emitted by the engine. Unlike sparks from a chain, which are abnormal and indicative of a problem, sparks from the exhaust are a normal and expected component of an internal combustion engine, but they still can cause problems.

While these sparks pose no risk to the operator, they still may be THE most dangerous part of the chainsaw–and that is saying something! The true risks of these sparks is the fires they could potentially cause and perhaps the damage you as an operator may be responsible for should a fire start.

The Risks of Taking Off a Spark Arrestor

In sufficiently dry environments, a chainsaw without a spark arrestor can ignite brush, leaves, and debris, causing potentially catastrophic and uncontrollable fires. Don’t count on being able to catch put out a fire that might start. Often, small sparks will start out extremely small and smolder for hours before escalating into a full-fledged fire. You may leave the job site only to get a call about smoke being spotted after you get home! This is why they are so dangerous.

I trust I don’t need to explain why starting forest fires themselves should be avoided. What may not be as obvious is that if a forest fire is ignited as a result of a chainsaw lacking a spark arrestor, you can be held liable. Of course, the specifics are dependent on the situation and local laws, but you never want to be in the situation of wondering about the specifics in the first place. Litigation is fun for no one but lawyers, so you are better safe than sorry!

Forest fire

In Some States, Running a Chainsaw Without a Spark Arrestor is Illegal

In certain jurisdictions, it isn’t a matter of if you should run a chainsaw without a spark arrestor, but a matter of if you can. Particularly for states more prone to forest fires, authorities take the risk of exhaust sparks seriously enough that spark arrestors are a mandated part of forestry operations, and ignoring those regulations can result in a citation and more severe consequences if a fire were to result. This is also true for all federal lands, where chainsaws used for logging operations are required to be equipped.

To check the legality in your state, contact your local state forest service office. In most cases however, these restrictions are limited to commercial operators, such as loggers and arborists, but they sometimes apply to homeowners and personal users as well.

Spark Arrestors Can Affect Performance

Reading up to here, it may seem insane that anyone would even want to remove a spark arrestor, but there are legitimate reasons. The material that comes out of the exhaust burning is partially-combusted carbon. In laymen’s terms, it is soot. Over time, it builds up on the mesh of the arrestor and suffocates the engine, killing performance and in some cases even stalling the entire engine.

For small-time users who run their chainsaws a few times a year, it really isn’t too much of a problem. It can be years before the arrestor is sufficiently dirty to affect performance. For professionals, however, it can be a matter of weeks before a brand-new arrestor is totally caked in coal. Despite their good intentions, these little pieces of metal screen can be extremely annoying.

Alternatives to Removing Your Spark Arrestor

Maybe you have decided not to remove the spark arrestor from your chainsaw, or maybe you are restricted from doing so. Don’t despair: There are some guidelines you can follow to ensure they stay clean and your exhaust remains unencumbered.

Run a Proper Air to Fuel Ratio With Non-Ethanol Gas

The number one cause of a frequently-gummed up spark arrestor is an air to fuel ratio that is too rich. If too much fuel is in the mixture, it won’t be able to be totally combust with the available oxygen. This leads to the build up of partially-combusted soot that is the true source of the problems with your spark arrestor. Consider re-jetting the carburetor to your climate and elevation to ensure the most optimum air to fuel ration.

Another helpful step is to use non-ethanol gas and high quality oil to reduce soot. While this may be a point of controversy in the two-stroke engine community, I find using the best quality fuels and oils can greatly reduce headaches in the long run by generating a cleaner burn.

Clean Your Spark Arrestor Regularly

Finally, it can be a good idea to include a cleaning of your spark arrestor as a regular part of maintenance. It isn’t too difficult of a task. Because it is only partially combusted fuel, the best way to clean it is to combust it entirely. With the screen removed, use a propane torch to heat the mesh up until it is glowing red. After it cools down, the now-fully-combusted material will easily fall off with a wire brush. Once you return the screen, your chainsaw will be back to running like it did the day you bought it! Alternatively, you can buy replacement arrestors for fairly cheap.

The Choice Is Yours

Ultimately the decision of what actions and risks you want to take with your chainsaw are yours and yours alone. However, the consequences may not be yours only. Many great and catastrophic fires have been caused by the careless actions of single individuals. Here at The Timberland Investor, we strongly advise you to not be that guy. Only You can prevent forest fires.

Without a spark arrestor, a chainsaw can start a forest fire.

Zachary Lowry

A forester from northern Maine, I spent my early career working for large timberland owners, managing forest land and investments in the form of managing timber harvest operations as well as planning and managing precommercial thinning, planting, and herbicide application programs. These days I work on my own land and help timberland owners large and small manage theirs.

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