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Thread: 2-stroke excel for ports, heads and pipes

  1. #31
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    27th April 2020 - 20:37
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    Thanks
    Yes, I haven't touched the sliders yet

  2. #32
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    I'm re-working some things at the moment (forgot the piston-pin diameter), so if anybody has some requests , now is a good moment ;-)

  3. #33
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    Quote Originally Posted by JanBros View Post
    I'm re-working some things at the moment (forgot the piston-pin diameter), so if anybody has some requests , now is a good moment ;-)
    Hello JanBros, this is my first post. I have been reading and reading and reading for a long time as a guest, now as a member. First of all big thanks to you, Frits Overmars, Jan Thiel and all the engine tuners that contribute here.

    Your Excel file has helped me A LOT to understand the theory, since it is a very good summary of the knowledge of the forum.

    I have good skills with Excel and its associated Visual Basic. As i am confined at home, not working now, please let me know if you need help to further develop your file.

  4. #34
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    30th May 2020 - 23:45
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    Misstake in Excel sheet????

    Hey jan,

    In the Moment i am working with your fantastic Excel!

    New for me bore 54 x 54,5 stroke are 247,82 capacity ? ...and msv is very high too
    ...think a tiny Misstake. .. ...page
    Head Design... when using Input from data ...without any changes...

    Thank you for heaving a quick look on it

    Grüße Wolfgang

  5. #35
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    19th June 2011 - 00:29
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    Hi,

    tnx for your kind words.
    ever wondered why people write manuals ? The writers do hope you read them before you ask questions a lot of time goes in writing them, and I'll be the first to say it's not perfect, but I still think there is a lot of good info in it.
    copied from it :

    Ticking this box :

    will make all the light green input cell’s meaningless, as all those parameters will be taken from the DATA sheet.



    if you look at "data new", you'll see that it's a 66.2/75 B/S engine, not a 54.5/54

  6. #36
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    30th May 2020 - 23:45
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    Tanks for Support! !

    Thanks jan for support and clarification!

    And if you allow me another question to pipe Design

    Surley your remember frits words to the restrictor size... depends on if a engine is thermally sound or not...

    On the underdogracing calculator there was the possibility to choose between air and watercooled. ..

    In our case the aircoolde factor for the restrictor of a aircooled classic enduro worked perfektly

    Do you remember what the factor was?

    It could help us for a thermal unsound minarelli 75 cc conversion to watercooled. ..with poor and small radiator

    Thank you very much jan!

    Grüße Wolfgang

  7. #37
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    19th June 2011 - 00:29
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    don't know what it was on the (I believe it was) underground site.
    For my mopeds I use +/- factor 1.7. FOS says 6.9mm, I use 12mm.

  8. #38
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    30th May 2020 - 23:45
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    Thanks for your help jan! *top*

    The underdog calc was not supported or approved by frits. ..right jan

    1.7 seems to be a lot. ..a advice with a lot of safety...

    However ...we have to test whats sound for our specific engine...and gives us power

    Grüße ! Wolfgang

  9. #39
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    19th June 2011 - 00:29
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    I don't think Frits will approve any calulator ;-)

    testing the nozzle for power will probably result in the same nozzle as a "thermaly sound engine" : a too small nozzle that could overheat your "thermaly not-sound engine" .

    I did test different diameters and chose one big enough that didn't lose too much power. I didn't say 1 .7 is a general rule, it's what I use for my MX-moped.

  10. #40
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    2 stroke tuning is always and everywere tecnical gambling like it jan!

  11. #41
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    Quote Originally Posted by JanBros View Post
    I don't think Frits will approve any calculator
    There are two main reasons.
    The first reason: suppose I make an adjustment in my concept, for example in the size of the restrictor diameter. This has already lead to various calculator versions that contradict each other on the internet. And because these calculators use the FOS name, I may be held responsible for things that are beyond my control.

    The second reason: some calculators offer multi-stage diffuser or reflector options that were not included in my exhaust concept and for which I cannot take responsibility.
    I recommend to keep things simple anyway. Fiddling with multi-stages before you have neared to an optimum means extra work which will slow your development down.

  12. #42
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    19th June 2011 - 00:29
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    That's why I said it Frits, and I include the picture with your concept, so people know the version

  13. #43
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    30th May 2020 - 23:45
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    Hey frits, hello jan



    My fellow and i made a pipe now, using the Excel. ..3 stage diffusor. ..2 stage baffle. ..

    And you both go to jail if it dosent work propperly

    Little joke!
    Thanks for your work...pleasure to use it!

    Maybe in about two weeks there is the rollout of the 75 cc minarelli

    Grüße! Wolfgang
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  14. #44
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    Hi, I have built a set of FOS pipes with 3 stage diffusers utilizing the JanBros spreadsheet. I enjoy everything about it so far, including the price. I donated these pipes for dyno work, and against the proper design, the team that received them insisted I use a fixed 23mm stinger. Currently working on a personal set that will be done properly. Just want to give a thanks to everyone who has put a great deal of work into making this happen. Click image for larger version. 

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  15. #45
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    Cool

    Quote Originally Posted by Wos View Post
    Hey frits, hello jan



    My fellow and i made a pipe now, using the Excel. ..3 stage diffusor. ..2 stage baffle. ..

    And you both go to jail if it dosent work propperly

    Little joke!
    Thanks for your work...pleasure to use it!

    Maybe in about two weeks there is the rollout of the 75 cc minarelli

    Grüße! Wolfgang
    To give your some Feedback ...and say thanks to you!!!

    Jan. ..frits...the spreadsheet lead us to new Dimensions in bulding pipes...

    Rollout today...the minarelli k6 has a unbeliefable broad useable band of power...7000 to 11500...peak set in speadsheet to 10000...75 cc... 18 hp...phenomenal for enduro use


    Grüße Wolfgang

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