Muffler Packing

Discussion in 'Tech Area' started by Valgars, Feb 6, 2020.

  1. Valgars

    Valgars New Member

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    Hello all! I am currently working on my original 1972 CT70. I’m currently working on the exhaust can anyone clarify if the exhaust contains any packing? I’ve pulled the diffuser and it’s just completely hollow past that until you reach where the baffles In the muffler body. My younger self would have possibly pulled any packing in it out so it would be louder, but my older wiser self finds it a little loud! I tried an amazon muffler and it was significantly quieter yet it didn’t fit with the skid guard or protector so I returned it. Thanks! J
     
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  3. racerx

    racerx Administrator
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    "Packing" refers to the treated textile material used to insulate the front of the main heat shield. You're talking about acoustic packing and none of these mufflers have it. The OEM muffler could be fitted with a removable end baffle, that's what tamed the noise.

    The reason why the cheapie aftermarket pipe was so quiet is that it's incredibly restrictive...15mm outlet...and you wouldn't believe the restrictive baffling inside the can. Those mufflers are built to meet the most stringent noise compliance standards around the globe, when fitted to a 49cc motor. They can be used on a CT70, very quiet but will strangle the motor. The reason you couldn't fit the engine guard is that you got one from a newer batch. Over time, "design drift" sets in with knockoff a.k.a. "clone" parts; the CT70 exhaust was the latest victim. It is possible to mod one of these to fit but, it's not the easiest thing to do, requiring cutting, welding and fab work.
     
  4. Valgars

    Valgars New Member

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    I was referring to something like this:
    https://www.revzilla.com/common-tread/how-to-repack-a-muffler-or-silencer
    Mine is literally just a metal shell when you pull out the diffuser. I thought that there was possibly some type of fiberglass heat resistant material between the baffle and the body of the muffler that would dampen the sound mine literally doesn’t change but slightly in pitch with the diffuser installed. All the videos I’ve seen on YouTube seem much quieter than mine.
     
  5. airblazer

    airblazer Active Member

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  6. Valgars

    Valgars New Member

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    Thanks! That answers it. Mine is the stock original muffler with some weld repair. It still has all the baffles in it. I was really digging around the internet to see if younger me had modified it! Every other bike I owned as a kid was straight piped, but the old 70 was the only one we never modified. I repainted the original and reinstalled after I returned the amazon special. I guess I’m just getting older instead of it getting loader. I may consider packing it lightly to bring the volume down some, but I’ll deal with it for now I’ve got other bugs to work out before I go anywhere other than around my neighborhood with it anyway. Thanks all!
     
  7. racerx

    racerx Administrator
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    Very difficult to add acoustic packing to a muffler this small, without killing flow. And, the OEM muffler is made from very thin sheetmetal. It's tricky to weld...and if there's any rust-thinning, it's like trying to weld onion skin.

    Tuning the exhaust note on these bikes is one of those deceptively challenging projects. Lack of cubic real estate dictates many things with these little bikes.

    The most practical solution (i.e. no surgery or welding required) will probably be fabbing your own removable end baffle. You're pretty well stuck with the OD. However, overall length, shape, and openings can be varied. Given time & experimentation you may get a result you like.
     

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