Repacking a Muzzy

This is not a difficult process, but it will require some careful use of a few tools, and 'delicate force' to disassemble/reassemble the pipe.

1. remove the canister from the header, and use a 1/8" drill to remove the old rivets from the endcap closest to the header (this endcap is out of sight if you damage it, and has a little more to grab on to when you pull it).

2. carefully pull the endcap off. this will likely take a decent amount of force; try to use equal force around the endcap so as not to damage it. with the endcap off, you can look inside the canister and see what's left.

3. now pull the baffle out, along with the remaining packing. in the pic below, about 1/2 of the packing was gone after 10k miles using the repacking method described later in this article. when i repacked my muzzy the first time (the packing having been done by muzzy at the factory), there was only 1/3 of the packing left after 8k miles.

4. clean off the baffle, and layout your new packing materials. you'll need one or two packages of silent sport or similar packing material (available at any local dirtbike shop), a roll of steel wool, and some picture hanging wire or similar wire.

5. first wrap the baffle in steel wool blankets, unwrapped from the roll. this will keep the fibreglass packing from breaking up as quickly from heat cycling. it will also prevent the packing from leaving the pipe very soon after it begins to break up.

6. then wrap the pipe in one or two sheets of fibreglass packing, depending on how much sound deadening you want. each layer less insulating ability to the baffle than the last, so keep that in mind if you're thinking about squeezing more than 2 layers on. use the picture wire to tie down the packing material, so it stays in place while you pack the canister with it, and so further reduce packing breakup once in use.

7. slowly insert the new baffle core into the canister, making sure the packing doesn't bind as it is inserted. wiggle the core around in the pipe once fully inserted to mate the core with the far endcap. replace the front endcap, lining up the clamp with the downturn in the pipe on the other endcap. it make help to tap it into place with a rubber mallet, but do not use much force. use new 1/8" (3 mm) short aluminum or stainless steel rivets and a pop-rivet tool ($10) to secure it. the aluminum rivets will be easier to drill out next time, but they may also vibrate loose between repackings.

If the pipe is not quiet enough for you, you can order a new baffle from muzzy that has a smaller core. This will reduce pipe performance slightly, however, and may require a rejet.