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Thread: the clean two-stroke thread

  1. #331
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    4th September 2017 - 10:39
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    Quote Originally Posted by Flettner View Post
    What are we looking at CECI?
    A little more information please.
    You've convinced me to go over to the dark side, now I'm intrigued by the opposite piston engines



    https://oldmotodude.blogspot.com/201...-2-stroke.html


    http://www.lambretta.it/velo2.php?lingua=ita



    As we can see, it is 125 with two pistons and if we compare the power figures with that of the garelli 125 with two pistons, it does come out very poor.

  2. #332
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    CECI, It certainly apears to be OP but its not Uniflow scavenge. An exhaust port at each end?
    I've reviewed this drawing again, now Im not sure what Im looking at.

  3. #333
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    Quote Originally Posted by ceci View Post
    Vespa? - Lambretta? but quite a tidy looking motor- for an OP - ie the first photo (if indeed it is an OP and not two engines tacked together for an experiment !)
    Strokers Galore!

  4. #334
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    Quote Originally Posted by WilDun View Post
    Vespa? - Lambretta? but quite a tidy looking motor- for an OP - ie the first photo (if indeed it is an OP and not two engines tacked together for an experiment !)
    Vespa 1951. one off (well two actually) for a streamliner. 125cc set a record of 172km/h. looks like at least one version of the engine was uniflow. I'll dig up a picture from a book

    Click image for larger version. 

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    Last edited by OopsClunkThud; 16th September 2020 at 17:47. Reason: adding photo
    Patrick Owens
    www.OopsClunkThud.com

  5. #335
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    Thankyou, much easier to see now.

  6. #336
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    Does that drawing make sense to you guys? (perhaps I'm a little slow of course!) - but as I see it, - if those are exhaust ports then they sure won't work very well in that position!
    Strokers Galore!

  7. #337
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    the pistons are are BDC in the drawing, those two conical ports are piston port intakes. the top view shows the exhaust and transfers better.
    Patrick Owens
    www.OopsClunkThud.com

  8. #338
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    Quote Originally Posted by ceci View Post
    I am in doubt as to whether these statements in this patent are true or fake.
    If true, why has it not been worked on evolving it?


    https://patents.google.com/patent/US...=4%2c627%2c390


    This is what I think are the answers to the questions I posed:
    The patent does not show what make and model of motorcycle they tested (it could possibly be an MZ).
    The data is given based on speed, which indicates that this data was possibly in a band of 2450 rpm (in this rpm range, the crankcase is still pumping).
    The operation of a standard engine from 1981 is very similar to that of a trial motorcycle (the power in trial bikes has not increased the power from that time to the present), as you can see in the graph of the GasGas TXT gives the 90% of torque before 2000rpm.
    The data on the reduction of consumption are true (the mechanism works since the crankcase pumps precompression)
    The reason why it did not succeed is that it works at a low rpm, but to reach maximum power more rpm is needed (here the crankcase no longer pumps enough precompression).
    I arrived at these beliefs based on data from SAE papers 960365
    Diaphragm Fuel Injection System (DFI)
    for Stratified-Charging of Small
    Two-Stroke Gasoline Engine

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  9. #339
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    Quote Originally Posted by OopsClunkThud View Post
    the pistons are are BDC in the drawing, those two conical ports are piston port intakes. the top view shows the exhaust and transfers better.
    Ok, after enlarging things some more I can now see that, - and BTW it was due to failing eyesight rather than a failing brain! (I hope).
    Strokers Galore!

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