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Goosedog

Repacking a muffler (YZ426)

13 posts in this topic

Got a stock YZ muffler that I've never repacked. I'm thinking that the rivets on the engine side of the pipe are the ones to drill, right? Can someone give me a short how-to? Also is FMF 's material as good as any to repack with, it's readily available for me anyway. And I've got the Yosh on my DRZ to do too. Thanks ~Mark

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Rivets are cheap. Drill out both ends. Make sure you're filling the whole canister evenly.

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Buy the silent sport packing that comes in a pre-sewn bag. DO NOT, I repeat DO NOT remove the carboard tube from the bag!!!! Don't ask me how I know.. Drill out the rivets at the tail end of the exhaust and pull the end cap off, the core will come out with it. Dispose of the old packing. Now slide the bag AND cardboard tube over the core. NOW remove the cardboard tube from the bag while the bag stays on the core. Presto your core has been wrapped with packing. Put some sealer on the end cap, slide it back together and install your favorite rivets or screws and enjoy!

Here is a really bad picture of what the silent sport packing bag looks like:

Picture of Silent Sport bag of packing

PS-> If you remove the cardboard tube from the bag before you slide it over the core, then you'll invent 101 new 4-letter words while trying to force the core through the [now collapsed] bag of packing.

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Drill out the rivets at the tail end of the exhaust and pull the end cap off, the core will come out with it.

I had the tail end off last year while installing a Promoto spark arresstor end cap and tried to see if the core would come out that way for future repacking, it didn't seem to budge so I figured it was attached to the other end. :banghead:

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Hmm.... I swear the core came out with my end cap, but it was several months ago that I repacked it.. I've got the 01' 426, stock exhaust. Damnit now I'm going to have to take it apart just to see how it fits together. :banghead:

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Damnit now I'm going to have to take it apart just to see how it fits together. :banghead:

I'll save ya the trouble, I'm gonna tear into mine after the TT ride this wk/nd. Speaking of which, why don't you come join us at Brown Mtn. this Sat?

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Thanks for the invite, I would love to! But I'm headed to the Seminole indian reservation MX tracks this weekend in Clewiston, FL. Anyone else headed out there?

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remove from pipe side. loosely wrap core.. the individual strand packing seems to quiet better than the mat stuff.

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I'll save ya the trouble, I'm gonna tear into mine after the TT ride this wk/nd. Speaking of which, why don't you come join us at Brown Mtn. this Sat?

We're racing MX at the Shelby Fairgrounds this weekend. Y'all oughta come on up. :banghead:

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Pulled the old packing out last night after drilling the "intake" side rivets, hope that helps anyone about to drill the endcap side. The core pulled right out of the sleeve and the old packing came right off. I was suprized at first because the old stuff looked in fairly good shape. It was all there, just real sooty. I was expecting 3 year old packing to come out in pieces and dust, but it was intact. I then repacked it with FMF brand insulation and riveted it all back up. I was thinking all along it had been a waste of time because the old seemed ok....then I cranked it today and WOW. The sound was back to that nice Yama-rumble and the popping was gone. The bottom end seems a lot snappier too.

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How often do you repack and what materials/manufacturer do you recommend? I used to use some fire-resitant fiberglass packing in my 2-Stroke days. About $3 at the hardware store. Is using this type material a big NO NO?

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