49cc's on a Schwinn

Discussion in 'Motorized Cruiser Bicycles' started by FOG, Mar 3, 2019.

  1. FOG

    FOG Well-Known Member

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    In post #155 I mentioned putting holes the back of the piston to feed the boost ports. But one of the PB guys, and what would I do without them, suggested slots instead.

    DSCF0941.JPG

    I like that a lot better than a couple of holes.
     
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  2. indian22

    indian22 Well-Known Member

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    FOG nice work. I've used alumi-weld rod to build up aluminum cases rarher than epoxy and it held up well. Though I know that many use epoxy to stuff cases with good result I'm not that trusting.

    Rick C.
     
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  3. indian22

    indian22 Well-Known Member

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    Slots are fine and look nice, though I use one big honking hole.

    Rick C.
     
  4. FOG

    FOG Well-Known Member

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    As usual I'm goin' off the deep end again by making my own cylinder head. I dunno why. Because I can I guess ... :)

    Compression ratio is obviously a big issue but I have this incredible resource at my fingertips we call the internet. I've always wondered what the correct way to calculate CR on a 2 stroke was, and now I know you have to take into account when the exhaust port gets closed.

    And there's a calculator for that ...

    http://www.torqsoft.net/compression-ratio.html

    Luv the net.

    Using that a 3cc chamber yields 9.38 to 1. Now I just gotta figure what dimension it takes to make a 3cc chamber. Back to the net ...
     
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  5. FOG

    FOG Well-Known Member

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    I found an online calculator for the volume of a dome which led to this ...

    40mmCylHead.jpg

    All that stuff on the right side is for the wee little cutter I gotta build next. I just kinda eyeballed the 1st one, no drawing, and it won't cut the combustion pocket without runnin' into the squish cut. :( It's good down to a radius of an inch or so but I need to reach in there and cut a 5/8" radius for the combustion pocket.

    DSCF0943.JPG

    That cutter ain't cuttin" in that far. Too big.
     
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