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Chainsaw Upgrades. Tips from a Professional

Powerful engines and a sharp cutting chain make chainsaws of great value to both homesteaders and professional woodworkers. Some users are perfectly fine with the chainsaw’s performance, but some want to optimize their chainsaw’s performance and take it to the next level. This is possible by performing some modifications. In this blog post, we shall look into the upgrades by which you can get the maximum power out of your chainsaw.

Chainsaw upgrades

Chainsaws can be modified to boost their performance and increase power. The basic idea is to increase the airflow through the engine. The most common method is muffler modification. This involves widening the muffler’s exhaust ports to improve the airflow at the exhaust. Another method is cylinder head porting, which widens the inlets and outlets of the cylinder, thereby providing more air for the engine to breathe effectively.

In this blog article, I will further elaboration on the various methods to modify your gas chainsaw.  

Modifications to a Chainsaw for Better Performance:

Gasoline-powered chainsaws use a two-stroke engine to power the chain drive. The engine intakes air which is mixed with fuel in the carburetor. The proportion of air mixed with the fuel determines the engine’s performance characteristics like torque, RPMs, etc. For the most part, engines can be tuned to their optimal performance by adjusting the engine components. These tune-ups include carburetor cleaning, filter replacement, and throttle adjustment.

The tune-ups do optimize your chainsaw’s performance. However, some tinkerers like experimenting with their engines to extract the maximum power out of them. Now, doing this seems tempting, but it’s not the easiest as it requires a great deal of knowledge, know-how of tools, and hands-on skill. The basic idea of chainsaw modifications is to allow the engine to breathe more air. Moreover, increasing the engine’s compression or the inlet air pressure could also maximize power.

Chainsaw Mods:

Speaking of chainsaw modifications, let’s get right into it by discussing some of the available methods. Always keep in mind that with these modifications, you will void your warranty.

Muffler Modification:

The chainsaw muffler primarily serves two functions. First, it suppresses the high noise levels produced by the engine. Secondly, it lowers the backpressure at the exhaust by providing a passage through its ports. Increasing the exhaust port area can further reduce the backpressure, increasing the compression and cranking up the engine horsepower.

The muffler housing contains an exhaust baffle and a spark arrestor screen. The baffle contains the ports from where the exhaust gases leave the engine. The arrestor screen catches up or arrests the sparks produced during combustion. In this way, only the combustion residual gases leave the engine.

Let’s take a look at the step-by-step method for muffler modification.

– Step 1: Locate and remove the muffler:

The muffler is usually present at the front of your chainsaw just above the bar’s attachment and under the chain brake. Use a socket wrench to remove the bolts securing it. Make sure you separate the muffler and the heat shield. While removing these bolts, take great care that you don’t damage the heat shield gaskets. If the heat shield doesn’t come off like in most saws, leave it as it is.

– Step 2: Access the baffle:

The baffle contains ports from where the exhaust gases enter the muffler. You may need to open the muffler’s casing to access the baffle holes. For example, in the Husqvarna 5-series models, the baffle is covered with a deflector plate that needs to be taken off before. Underneath the plate, you would be able to see both the baffle and the spark arrestor screen.

– Step 3: Enlarge the ports:

The exhaust ports at the baffle need to be enlarged to make the exhaust flow seamless, and the back pressure is reduced. You would need a drilling machine to enlarge the holes and a ruler to measure their dia.

I recommend the port diameter around 80% of the main exhaust outlet of the muffler for maximum power output. Going higher than this would cause no increase in power but instead affect the air-fuel mixture composition. Hence, first, use the ruler to determine the approximate dia of the main exhaust outlet. If the outlet dia is 1-inch, your maximum port size can be 4/5-inch. Hence, use a drill bit of 0.8 inches to enlarge the exhaust ports.

– Step 4: Clean the arrestor screen:

After enlarging the ports, it’s also important to clean the spark arrestor screen. Doing this would further ease up the flow as the clogged debris can choke the flow, eventually increasing the backpressure at the exhaust. To clean the arrestor screen, use a torch to fire up and remove the debris stuck in the wire gauze. After cleaning, reinstall it into the muffler.

– Step 5: Exhaust outlet modification:

This step is optional if you’ve done the above port modification. I would advise you to do it if you have intermediate-level experience in workshop skills like machining and welding. If you’re a total beginner, it’s better to hire a professional for this job. Doing this could top up the performance to some extent and further improve the engine’s breathing.

To perform this modification, you would need a metal pipe of a couple of inches in length.  Ideally, its diameter should be greater or equal to that of the already existing exhaust. Use a drill bit of the same size of a few millimeters less than the pipe and drill a hole on the muffler casing externally. Afterward, braze or weld the metal pipe above the hole.

– Step 6: Install the muffler:

After the welding’s done, let the muffler cool down. It is better to wash it thoroughly with water and clean the metal chippings or any debris inside. After it dries down, reconnect the heat shield and the gasket. Reattach the muffler to the chainsaw body using the bolts removed initially.

Throttle Adjustment and Tuning:

After modifying your muffler, a quick tune-up can further the performance of your engine. Due to the modification, now more fuel tends to leave your engine along with air. Due to the widening of the ports, the less air-fuel mix is deflected back at the exhaust. Hence, your engine would be running lean after a muffler mod, and it should be tuned to a rich setting for optimum performance. Running an engine on a lean setting can cause it to overrev and eventually overheat its components.

– Step 1. Adjust the Low-Speed Screw:

The engine RPMs can be controlled by adjusting the low-speed setting screw marked by L on the carburetor when the engine is idle.

  • Start the engine: Turn on your chainsaw and make sure the chain is tightened. Allow the engine to run idle for a few seconds. Take note of if the engine runs smoothly or if it dies while idling.
  • Set the screw: If the engine dies while idling, tighten the Low Speed (L) screw using a screwdriver to raise the idle RPM. As you tighten it further, you will reach a point where the RPMs begin to fall. Note that spot in your mind.  Loosen the screw from that spot so that the RPMs rise again until they start to drop. Make a note in your mind of the second point.
  • Find the ideal spot: Now, the perfect screw setting should be somewhere between these two positions. Turn the screw until you locate the sweet spot and then leave it unchanged. At this time, the idle RPMs would be plenty to keep the engine running. Moreover, as the trigger is pulled, the engine response will be much faster and lag-free.

– Step 2: Adjust the Idle:

Following the low-speed adjustment, the chain may begin to rotate because the mixture is lean enough to engage the clutch. If your chain starts to rotate, loosen the idler screw until it stops. This is critical because a chain rotating at idle is extremely dangerous. If your chain does not rotate, skip this step and move ahead.

– Step 3: Set the High-Speed Screw:

The maximum engine RPMs are controlled by the high-speed setting, which is the focus of this blog post. An over-revving chainsaw is highly hazardous to your engine, as it can not only score the piston but also overheat its components, resulting in a total seizure.

It’s best to have a digital tachometer on hand to obtain an idea of the engine RPMs when adjusting your high-speed screw. If it is not available, consult your owner’s handbook to determine the best setting for the H screw. 

  • Pull the trigger: Start your chainsaw and pull the trigger to increase the RPMs.
  • Tighten the screw: With the throttle wide open, tighten the H screw all the way. Take note of the reading from the tachometer if one is available.
  • Set the screw: The aim is to loosen the screw by about half a turn so that the maximum RPMs at wide-open throttle are reduced by 1000-2000. That is the best setting for your engine. Always remember to keep your engine at a couple of thousand RPMs lower than its maximum prescribed RPMs.

How do I get more Power out of my Chainsaw?

For most chainsaw users, taking their performance to a higher is quite an intriguing phenomenon. While doing this could void the device’s warranty, many users will tell you it was worth it. Gas-powered chainsaws can be made to run better by improving their engine’s breathability. When more air flows through the engine, more power is generated. Let’s look at the ways of maximizing your chainsaw’s power.

1. Tune-Ups:

If you notice a drop in your chainsaw’s usual performance, consider performing a tune-up of its components. This includes checking the spark plug, cleaning the filters, servicing the carburetor, checking and cleaning the fuel tank. When your device’s filters are dirty, this could upset the air-fuel mixture and can cause a performance decline. Cleaning the filters and carburetor jets improves the engine breathability and contributes to seamless performance.

2. Muffler Modification:

The chainsaw muffler carries and removes the exhaust gases from the engine into the environment. Modifying the muffler by improving its exhaust area enhances the engine’s combustion. This also makes the engine run a lot cooler as the exhaust gases carry the excess heat with them. Furthermore, an increase in exhaust area lessens the backpressure on the engine and improves compression, thereby boosting the performance.

3. Cylinder Head Porting:

Another tried and tested method of improving chainsaw performance is cylinder porting. Porting is the widening of the cylinder’s inlets and outlets. This increases the air flow rate through the engine and enhances breathability. The best way to port a cylinder is to use a Dremel tool with a diamond or a carbide burr.

The material removal should be done carefully as the material cannot be re-added again. Successfully performed porting increases torque, resulting in higher cutting speed, faster and aggressive cuts with less bogging down of the engine. The downside of this method is that it requires a great deal of knowledge and practical experience of working with two-stroke engines. If you aren’t an expert in this domain, you shouldn’t try it by yourself as you could end up damaging your engine.