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Muffler Repacking

These instructions use a trinity muffler with installed turn-down, but most mufflers will have a very similar design to the example used. Some mufflers (e.g. OEM for "track" dirt bikes like CRF and YZF) will have rivets instead of bolts and will require drilling of the rivets and replacement rivets and installation tools. Other mufflers may have the core fixed to either end-cap, but the procedure will be very similar.

  1. Prepare your muffler

    1. It's often possible to repack with the muffler installed in the vehicle. If yours can be removed easily, it would be recommended. This will allow you to do the work at a comfortable level in a clean environment to prevent scratching the muffler sleeve and end-cap.

    2. Clean your bolts! In use, the muffler bolts may collect dirt in the drive which will prevent full engagement of the wrench or socket. If this happens it is VERY easy to strip the head of the bolt. It's best to wash your muffler before removal (make sure to plug the outlet) but a stiff plastic brush (like a toothbrush) can be used to clean the fasteners once the muffler is on the work bench.

  2. Loosen fasteners & Remove

    Break them free all the way around first before removing them completely. Some mufflers will NOT have removable fasteners on the top, these will have the fasteners on the inlet cap and the muffler sleeve will come off with the outlet cap.

  3. Remove the end-cap

    On this muffler the core floats between the inlet and outlet cap, but some mufflers have the core attached at either end. You should be able to wiggle the cap to get it free, avoid prying in the seam between the sleeve and cap. Some mufflers have a high temp sealant that will make removing the cap difficult, but it will come out with enough pulling force. If you have bolts in the end of the cap, you can thread in a longer bolt to use as a handle.

  4. Slide out the core and packing

    Most mufflers will have a floating core than can be slid out from the muffler with the packing material. Others may have the core attached at one end and you will have to remove the entire sleeve from around it. e.g. Most FMF 2 Stoke mufflers have the core welded to the inlet cap and the sleeve and outlet cap are removed as one piece from the core.

  5. Inspect/Replace packing

    Check the following and replace packing if at all questionable (See Trinity's video for an example of fresh packing)

    1. Loose or missing packing material.
    2. Voids in packing.
    3. Torn or damaged packing.
    4. Burnt or singed packing.
    5. Oil or carbon saturation.
    6. Water or mud saturation.

    If the perforations in the metal core are becoming choked by carbon, it can be cleaned with solvent and a wire brush. The packing should be "tight" to the core and uniformly thick. Trinity uses a pillow pack with built-in adhesive the holds the packing tightly, but loose packing can be installed / tightened using masking tape.

  6. Install core

    Make sure that the packing will be a tight fit, but has enough clearance to slide into the muffler sleeve. Install the core and align it with the inlet cap; it will fit into a socket or spigot in the cap. Be careful not to trap any of the packing between the cap and spigot.

  7. Install last end-cap

    If your muffler had a sealing compound, you should put some on the end cap now. A high-temp silicone compund is usually used. Avoid strong adhesives like epoxies and "quick steel". Once the core is in, you'll want to center it as best as possible and slide the remaining end cap back into place. You can reach your finger into the outlet to adjust the alignment of the core. Once aligned, it should slide all the way on. Make sure that the cap is on with no gaps.

  8. Torque bolts

    It's usually a good idea to put some anti-sieze on steel bolts when going into an aluminum end-cap, but at least lube the bolts with light oil when starting them. Thread ALL the bolts down hand tight, then torque them to specification in a criss-cross pattern. Be sure you include any locking washers that came off when installing the cores. Some manufacturers will specify a torque rating for the cap bolts; you can use the following torque specifications of none are supplied:

    Aluminum End Cap w/ Steel Bolts
    Bolt SizeTorque Range
    M52.5-4 ft/lbs
    M65-6.5 ft/lbs
    M812-16 ft/lbs
    #102-3 ft/lbs
    1/4-205.5-7 ft/lbs
    5/16-1811-15 ft/lbs
  9. Re-Install muffler if removed and run the vehicle :-)

    New packing will often smoke on the first run; this is normal and will stop after a short while.

We have many brand specific and universal repack kits available and can repack your muffler for you in our service department. You can even send us your muffler to have this done. Please contact us if you have any questions or for assistance finding the best packing for your muffler.

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