Introduction: Chainsaw Muffler Modification - 572XP Husqvarna

By Dasos Ellas
About: I'm a freelance arborist, farmer, chainsaw mechanic and porter for hire. I do chainsaw mods and repairs in my free time.

In this Instructable I'll show you the basics of modifying a 5-series Husqvarna exhaust. I'm working on a 572XP in the pics. The 5-series husqvarna exhaust are similar so the steps will be basically the same for the 550XP, 560XP and 562XP, including the equivalent Jonsered models.

Note: some models may contain and inner baffle that will need to be removed or modified. The 572XP exhaust in the pics does have a small baffle, but it is much easier to work with than some other models.

Also, this is not the only way to modify the 572XP exhaust or any other 5-series Husqvarna exhaust. The way I'm showing here is to retain the spark arrestor screen for those of us that live in fire prone areas. Some may be required to have the spark screen by local authorities and forest services. Where I live there are no laws regarding the screen, but setting a forest fire will end you up in jail even if it was unintentional.

Supplies

T27 t-handle

Exhaust deflector

Vise

High-temp paint

Dremel, rotary tool, die grinder, etc.,

Drill with 1/4" bit

Welder or torch for welding and brazing

Parts or tool tray

Step 1: Get the Muffler Off the Saw

Warning: modifying a muffler while still on the saw may cause metal chips to enter your engine and damage it. Remove all mufflers prior to modification and place the chainsaws out of the way of all grinding debris while performing the mods.

The newer 5-series Husqvarna saws use T27 Torx primarily throughout the saw. This is no different for the exhaust bolts. Release the chainsaw brake and remove the bar and chain for clearance and safety.

Using a T27 Torx t-handle, remove the 4 bolts holding the muffler in place. These may be torqued pretty tight so securing the saw while loosening the bolts may be necessary. I don't advise using impacts when working on saws. Saws are made from aluminum, magnesium and plastic--you can easily strip the holes if screws are over-torqued.

Store your bolts in a small bowl/jar or magnetic parts tray (recommended). Remove the muffler and heat shield from the saw. Remember the orientation of the heat shield for reinstall. Also, there will be a gasket between the muffler and the heat shield. Don't damage the gasket or you will need to acquire a new one from your dealer. If it is stuck to the muffler like mine, it's better to leave it there. Set everything aside and store or wrap the saw to protect from flying debris.

Step 2: Layout and Mod Planning

If you don't live in a fire prone area, there are additional modification options available to you. Opening the front of the muffler and brazing in a piece of Stainless Steel pipe (see 1st pic above) is a popular way to modify 5-series Husqvarna exhausts.

The option I've chosen is to modify the exhaust via the existing exhaust gas exit from the factory. This will allow me to utilize the factory spark arrestor screen, or upgrade to a more free flowing screen.

Note: spark arrestor screens do their job well, but there is a drawback - flow restriction, especially when clogged. They can make a chainsaw run terribly, or not run at all if fully clogged. There are some sellers on eBay that provide replacement screens that have a more loosely woven mesh which allows better flow. I won't go into the mesh options, or make any recommendations now, so as not to sidetrack the Instructable.

Step 3: Removing the Old Deflector and Modding the Baffle

You'll need to cut the factory deflector off. Securing the muffler in a vise helps. Just remove the upper portion that sticks above the exhaust body. After removing the factory deflector, you'll be able to see the baffle.

Above the baffle there's a flange or an exhaust duct that I've also removed using the die grinder (see pic 3 above).

Now that the baffle is fully accessible from the top opening, you can begin to modify the baffle to your liking. I opened about a 13mm hole in mine (see pic 4 above).

Caution: remove all burrs from grinding. Leaving burrs or grinding debris in the exhaust can damage your engine.

Step 4: Installing the New Deflector and Painting

It's important to pay close attention to sizing your deflector to the surface where it will be mated. This prevents exhaust gases from leaking backwards toward the cylinder where they cause heat build up and damage plastics.

There are a number of ways to attach the deflector to the exhaust. I prefer brazing, welding TIG or MIG or rivet nuts. Screws or rivets are an option, but less preferable in my opinion.

I decided to weld my deflector in place, as I have a Synergic MIG that is capable of welding less than 1mm thick steel. Anything else will have a tendency to blow through the thin metal. Also, there is a strange copper colored metallic coating on these Husqy exhausts that plays havoc with welders, so make sure you are fully capable to weld these before you begin.

After sizing the deflector and welding it in place, you can sand, clean and paint with a high-temp paint. I used a brush on variety here as the sprays I have used in the past weren't very good. I'll sand this one and then spray it so the appearance is better.

Step 5: Install on the Saw

Remember to remove ALL grinding chips and debris prior to install on the saw. Washing the muffler inside and out with a hot soapy solution is the best way to remove debris. Flush thoroughly with pressurized air or water prior to install.

Install the heat shield gasket and muffler bolts in reverse order that you removed them. Make sure the gasket is in place and both upper screws are in the proper orientation with the gasket. The bolts with the larger heads are the lower bolts.