How to Repack Dirtbike Mufflers

Unlike the series of baffle plates and tubes used by most street-ridden motorcycle mufflers, dirt bike mufflers employ a perforated inner core tube wrapped in a consumable fiberglass mat called packing, to reduce the dirt bike’s exhaust noise. Over time, the packing deteriorates as the heated exhaust gases burn off the fiberglass material, resulting in an increase in noise and a decrease in power. While the job is easily farmed out to a local dealership, repacking the muffler is a straightforward procedure, normally accomplished on your own within an hour


1) Loosen the muffler’s exhaust clamp and remove its hanger bolt, using a socket wrench. Pull the muffler from the dirt bike’s frame and set it down on a clean work space.

2) Remove the muffler’s outlet cap, using an electric drill and a 1/8 inch drill bit to remove the outlet cap’s rivets. Tap the sides of the outlet cap lightly, using a rubber mallet, until the outlet cap is easily removed from the muffler housing.

3) Put on a pair of work gloves and reach into the muffler. Grasp the wrapped inner core tube and pull it out of the muffler housing.

4) Unwrap the inner core tube and discard the old packing material.

5) Place the inner core tube on the edge of a new sheet of fiberglass packing material. Roll the inner core tube to snugly wrap the packing material around it. Slip the freshly-wrapped inner core tube into the muffler housing.

6) Spread a thin coat of high-temperature RVT sealant around the base of the outlet cap. Seat the outlet cap onto the muffler housing, using light taps with a rubber mallet. Wipe away the excess RVT sealant, using a shop rag.

7) Rivet the outlet cap in place, using the original rivet holes on the muffler’s housing. Insert a 1/8 inch rivet into each holes, using a rivet gun.

8) Reinstall the muffler onto the dirt bike, using a socket wrench to tighten the muffler’s hanger bolt and exhaust clamp.

9) Start the dirt bike’s motor to season the new packing material. Run the dirt bike until the muffler stops smoking or producing sparks.

Extra Tips:

*Muffler removal and disassembly procedures vary between dirt bike models and manufacturers. Refer to a service manual provided by your dirt bike’s manufacturer for specific details regarding this task.

*Work on the motorcycle only after the muffler is cool to the touch. Smoke and sparks may appear from the muffler during seasoning. Do not stand behind the dirt bike and keep the area directly behind the muffler free of flammable materials.

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