Home made 4 stroke mufflers

Discussion in 'Rack Mounted Engines' started by scrollerguy, Oct 24, 2007.

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  1. scrollerguy

    scrollerguy Guest

    :???:Hi all, I did try to use the search first, but being color blind, I couldn't make out the numbers or letters, so here goes.

    Does anybody have any experience making a muffler for a 4 stroke? I have decided that I would like a little bling on my bike. I have cut up handle bars, and welded the bends, and now I'll try to make a muffler.

    Flowmaster uses a delta baffle inside theirs, how hard can it be to semi-duplicate, on a smaller scale of course, these angled fins?

    Maybe use a strip of steel with small pieces of flat stock welded in a delta shape, then inserted into a larger pipe than what comes from the motor?

    Any and all ideas would be appreciated. Thanks!


  2. DougC

    DougC Guest

    You don't need to use anything that complicated. Assuming the muffler is (for example) a cylinder shape and 3 inches diameter and 12 inches long, the exhaust from the engine should enter into the center of one end, and then the outlet should be placed NOT in the center--near the edge of the other end, and stick inwards an inch or two as well as outwards an inch or so.

    The two biggest factors are the thickness of the metal you use, and the internal volume of the muffler. What's inside really doesn't make much difference (as I've heard) so I just leave it empty space inside.

    You can see here, I'm using an old disposable gas cylinder. This one was oxygen but propane and mapp cylinders are no different. Run them empty, then drill a small 1/16" hole somewhere first, and then have your way with it--grind it/cut it/torch it, it's safe to cut up:
  3. DougC

    DougC Guest

    I got this muffler setup on today, didn't get any photos yet...

    While the tank-muffler does get rid of most of the exhaust noise, a lot of the noise is still there, it's mostly mechanical and coming straight out of the engine. Overall the muffler didn't really help a whole lot in making the Robin/Subaru 35cc much quieter.

    I haven't tried the rubber-between-the-fins business yet.
  4. Hive

    Hive Guest