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Thread: the clean two-stroke thread

  1. #31
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    Husa's long stroke idea interested me,as I have no fancy calculator gizmo stuff,decided to do it by hand/mind..Tried to find the longest stroke 2stroke motorcycle engine,found the KX500(86x86),has a 145mm rod,scaled that up for a 105 stroke =177mm,went to torqsoft and plugged in 180 and 120 degree for a 105 stroke/177 rod motor,got the numbers and made a full scale drawing,looks quite strange compared to the normal race stuff we see..Click image for larger version. 

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    Perhaps this is all wrong,but it is interesting to see how bore to stroke ratio alters port dimensions for a set degree angle..

  2. #32
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    Quote Originally Posted by 190mech View Post
    Husa's long stroke idea interested me,as I have no fancy calculator gizmo stuff,.........................
    Perhaps this is all wrong,but it is interesting to see how bore to stroke ratio alters port dimensions for a set degree angle..
    Sometimes the "suck it and see/trial and error" approach is the best way to go! - guess it depends on what the goal for the machine is! - This thread is not only for high performance machinery, but for finding out how we can save the two stroke before it disappears completely!

    I believe that it would take a massive shift from the norm to get the two stroke back to where it should be! (maybe not impossible), but it's future is really controlled by ignorant people in high places and their "greenie" supporters, so first off we need to look for something to change their minds! (like NO visible smoke), -
    It probably isn't the main problem, but how it is "seen to be" by a lot of people, does matter and will also affect its chances of survival,
    (whether we like it or not!).
    Strokers Galore!

  3. #33
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    4th September 2017 - 10:39
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    The success of the TPI as an anti-pollution system establishes the future of the 2S within the semi-direct fuel injection system.
    And how can TPI be improved? My opinion is that it must be transformed to meet the requirements described in the first photo, lower price and weight (framed), and only then can it reach the continents (framed) in the second photo.
    What transformation ?:
    fewer components is less weight and less price.
    How can that be done ?:
    changing the way it is controlled (setting aside the electronics)
    changing the way fuel is pumped (no energy consumption to perform it)
    changing the way of injecting (with exclusive injectors)
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  4. #34
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    12th March 2010 - 16:56
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    No real interest in opposed piston uniflow?

  5. #35
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    22nd November 2013 - 16:32
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    Ceci, on Page 1 of this thread you posted a pic of a Derbi that clearly has a catalyst. I looked up Derbi and, yes, it is real and it meets Euro4 and it looks to have a carb. One would think that TPI plus the cat would be pretty good.
    Can't deny the incremental cost of incorporating TPI though.
    "Success is the ability to go from one failure to another with no loss of enthusiasm.”

  6. #36
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    Quote Originally Posted by Flettner View Post
    No real interest in opposed piston uniflow?
    Interest yes,but not enough to invest.
    We are dreaming one or two cylindered engines and when synchronized by gears we get noise and trouble in great amounts.
    Having piston controlled exhaust is reason for demise of normal small two strokes.Having one piston doing nothing else is not improving chances much.
    Many many years ago I wrote that the Junkers problem was best solved by using power symetrical from the two cranks be it either driving two propellers or generators.
    I closed my eyes to the fact that this does not solve the piston rings over exhaust ports problem.
    The two AC generator scheme worked first try but do not solve the ring problem


    https://web.archive.org/web/20080501...c2/junkers.htm

  7. #37
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    22nd November 2013 - 16:32
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    Niels,

    "I closed my eyes to the fact that this does not solve the piston rings over exhaust ports problem.
    The two AC generator scheme worked first try but do not solve the ring problem"

    What specifically do you mean by the ring problem.
    "Success is the ability to go from one failure to another with no loss of enthusiasm.”

  8. #38
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    Quote Originally Posted by Niels Abildgaard View Post
    Interest yes,but not enough to invest.
    We are dreaming one or two cylinderebd engines and when synchronized by gears we get noise and trouble in great amounts.
    Having piston controlled exhaust is reason for demise of normal small two strokes.Having one piston doing nothing else is not improving chances much.
    Many many years ago I wrote that the Junkers problem was best solved by using power symetrical from the two cranks be it either driving two propellers or generators.
    I closed my eyes to the fact that this does not solve the piston rings over exhaust ports problem.
    The two AC generator scheme worked first try but do not solve the ring problem


    https://web.archive.org/web/20080501...c2/junkers.htm
    This one seems to go alright, Neils. It did a lot of work in this boat, until the boat hull owner wanted it back. Still got the engine tucked under my bench.
    https://youtu.be/uiXsPkP9jvw

  9. #39
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    20th January 2010 - 14:41
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    Quote Originally Posted by ken seeber View Post
    Niels,

    "I closed my eyes to the fact that this does not solve the piston rings over exhaust ports problem.
    The two AC generator scheme worked first try but do not solve the ring problem"

    What specifically do you mean by the ring problem.
    i assumed he meant the oil needing to lubricate it and getting passed into the combustion chamber.

    Quote Originally Posted by 190mech View Post
    Husa's long stroke idea interested me,as I have no fancy calculator gizmo stuff,decided to do it by hand/mind..Tried to find the longest stroke 2stroke motorcycle engine,found the KX500(86x86),has a 145mm rod,scaled that up for a 105 stroke =177mm,went to torqsoft and plugged in 180 and 120 degree for a 105 stroke/177 rod motor,got the numbers and made a full scale drawing,looks quite strange compared to the normal race stuff we see..Click image for larger version. 

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    Perhaps this is all wrong,but it is interesting to see how bore to stroke ratio alters port dimensions for a set degree angle..

    The idea with the super long stroke is we dont need to rev it to the moon for non GP
    and the port area will be made up with height rather than width and overlap %?
    less rev less need for overlap anyway. Smaller bore less squish width less so less emissions
    smaller bore tighter and smaller combustion chamber
    The Conrod length on MX bike especially big bore ones were in my opinion dictated not by engine performance, but ability to fit into the same or similar chassis as a 125 and 250
    The rod ratio should be at least 2x stroke min
    but we can play with this and the pin offset esp with very long strokes.
    IN HINDSIGHT MAYBE 180 DEGREES IS TO MUCH EX DURATION

    On your picture i think the lower part of the EX port needs to be blocked off about 10mm from the bottom
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    Some of the Trails bikes had either direct or throttle body injection
    I will dig up some EXP stuff
    but basically it was a trapping valve that allowed it to autoignite when it would be 4 stroking.
    although the racer was originally EFI Honda said it could be run as a carb they designed it to be emissions friendly 400cc but the power of a 650 4t
    Quote Originally Posted by Katman View Post
    I reminder distinctly .




    Kinky is using a feather. Perverted is using the whole chicken

  10. #40
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    22nd November 2013 - 16:32
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    At Orbital, we also did 2 versions of an externally scavenged engine: 3 cyl 1.0 litre and 6 cyl 2.0 l. Both were externally scavenged with a blower and both had a pressure fed plain bearing crank and rods; ala 4 stroke wet sump.

    Pistons incorporated the same combustion bowl as per the other 2 stroke injected engines that we were working on at the time. The prime reasons for the engines were to demonstrate a reduced cost of mfg and improve the NVH, more specifically the noise (mechanical clatter). The latter was achieved.

    The pistons were full skirted with an oil ring at the base of the skirt, this stopped a few mm below the bottom of the exh port.

    Obviously there was shitloads of oil on the bores, but this did not cause any perceived smoke issues. I am pretty sure we used 2 stroke oil as this does not have the zinc and phosphorous additives (that are necessary for 4 strokes due to the extreme pressures of the cam lobes), these causing problems with poisoning the catalysts.

    Downsides are a heavier piston and more friction.

    This pic shows a piston we did for a customer (86 * 86), very similar in style to the ones we used.

    Click image for larger version. 

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    "Success is the ability to go from one failure to another with no loss of enthusiasm.”

  11. #41
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    Quote Originally Posted by Flettner View Post
    This one seems to go alright, Neils. It did a lot of work in this boat, until the boat hull owner wanted it back. Still got the engine tucked under my bench.
    https://youtu.be/uiXsPkP9jvw
    Somewhat noissy.
    I have seen a Junkers engine like that in Dessau made by a mr Heintz running HCCI on LPG ( no mean feat )and it made less noise and sired no ofsprings either.

  12. #42
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    24th February 2013 - 08:12
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    Regarding emissions. The following preview of a SAE paper is interesting, the last two pages not in the preview is not necessary to get the picture. Proposals to counteract Particle emission (PM) is not presented in detail (EURO5 demand if using DI but not PI, Flettner-TPI for example).

    https://www.sae.org/publications/tec...-0042/preview/

    BRP has filed for PCT patent with one solution for rotating exhaust valves. Filed end of 2017. WO2019101981 (A1). To me it looks as if it will be granted at some point.


    Flettner, you could maybe consider to apply patent on some of your inventions, I think. You can check, often countries have programs to help inventors to finalize their applications/designs and to get help from for example a Patent Attorney. You are obviously working on solutions that can be used in for example hybrid solutions. Solutions aiming for decreasing pollution and/or having the potential to give job opportunities, in the end, is interesting for the governments.

  13. #43
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    Quote Originally Posted by Norman View Post
    Regarding emissions. The following preview of a SAE paper is interesting, the last two pages not in the preview is not necessary to get the picture. Proposals to counteract Particle emission (PM) is not presented in detail (EURO5 demand if using DI but not PI, Flettner-TPI for example).

    https://www.sae.org/publications/tec...-0042/preview/

    BRP has filed for PCT patent with one solution for rotating exhaust valves. Filed end of 2017. WO2019101981 (A1). To me it looks as if it will be granted at some point.


    Flettner, you could maybe consider to apply patent on some of your inventions, I think. You can check, often countries have programs to help inventors to finalize their applications/designs and to get help from for example a Patent Attorney. You are obviously working on solutions that can be used in for example hybrid solutions. Solutions aiming for decreasing pollution and/or having the potential to give job opportunities, in the end, is interesting for the governments.

    HaHa, sadly not ours. Talk talk talk but no do, thats New Zealand for you, I have approached two universities now, not interested. The only person I could intetest years ago was John Britten but he wanted OP uniflow to get around the number of cylinders rules for GP racing not emissions.
    Patent Attorneys are not efficent, financially, personal experiance.
    Who is seriously intetested? There are a lot of talkers.

    NZ has now stopped selling E85, I talked to the Green party about what they might do to fix this, they just said we all need to be electric, with seemingly not a thought to where that 'magic' might come from.
    Boy do I sound like and angry old man.

    I'm in this for the challenge, but I will be keeping my OP developments to myself this time. My problem is I enjoy this kind of work, pitty It doesn't pay.

  14. #44
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    Quote Originally Posted by Flettner View Post
    HaHa, sadly not ours. Talk talk talk but no do, thats New Zealand for you, I have approached two universities now, not interested. The only person I could intetest years ago was John Britten but he wanted OP uniflow to get around the number of cylinders rules for GP racing not emissions.
    Patent Attorneys are not efficent, financially, personal experiance.
    Who is seriously intetested? There are a lot of talkers.

    NZ has now stopped selling E85, I talked to the Green party about what they might do to fix this, they just said we all need to be electric, with seemingly not a thought to where that 'magic' might come from.
    Boy do I sound like and angry old man.

    I'm in this for the challenge, but I will be keeping my OP developments to myself this time. My problem is I enjoy this kind of work, pitty It doesn't pay.
    Hondas original NR had 8 pistons but 4 combustion chambers it was ruled to be legal but Honda didnt want to be accused of cheating so went oval pistons.
    You need to get get a Elon musk or Bedos to sponsor you.
    The guy that did the Modern scott Silk had non Schnuerle porting
    they were deflector and gave good MPG and power.
    but were hamstrung with certain Scott designs like the overhung crank.
    Something like these would be great light agile and a spondon chassis.
    target a R6 performance i guess.
    https://www.pressreader.com/australi...82385513988156


    Some pre war Villiers they were 4 transfers and two exhausts with one exhaust over the inlet. 9D.
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    i cant find a decent pic but they are described as 4 transfer so i assume its 2 front and 2 rear.
    Quote Originally Posted by Katman View Post
    I reminder distinctly .




    Kinky is using a feather. Perverted is using the whole chicken

  15. #45
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    I don't think that a guy with a home workshop ( even coming up with radical and successful stuff would really stand a chance in the patent scene today without a big company (with smart lawyers) backing him and shouldering the costs !

    Then there are big and influential people in this world, using politics and financial clout to twist a patent to suit themselves or in some cases just ignoring it altogether!

    So yeah, a good idea to carry on as enthusiasts and just keep our little victories to ourselves! - I'm getting to an age now where I can not see any point in guys trying to successfully develop a product, just to have it snatched from under their noses and being unable to do a thing about it!

    Life's too short to put yourself through all that stress - I watched a guy from Europe (not too long ago) trying to be big time in the international scene and who more or less went down still kicking and fighting and finally getting nowhere - very very sad to see!) - but still, the sense of achievement you would get from beating the big boys from home must be fantastic!

    I will never achieve even that, but I'm just as enthusiastic as I was 54 years ago when I first arrived in NZ - and way before that!!
    Strokers Galore!

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