Free 2 stroke Expansion Chamber Calculator Software Update

greetings two-stroke fans. A very quick
update here now this is just a progress report on the software the two-stroke
expansion chamber calculator it’s about a week off there’s a couple of little
things I want to do but I just want to give you a quick run through of the
software it’s basically fairly simple you just
put your port timing RPM exhaust temperature these things are all
explained in due course I just left them open so that you can you know edit them
if you want to it’s got a help system you just wave over the window and I’ll
tell you what each each box is in expanded form and explanatory so that’s
the help system so I won’t have a separate help file so you just wave it
over if you want to use that I’m just doing a quick demo one only the tab keys
working order so you can just use keyboard if you want to there’s no user
500C I’ll put the designations in there for temperature in Celsius but
it’s all metric exhaust port 32 to 20 I might put a a converter in there for
Imperial I’m not sure yet and then we can just did pipe calculator and get a
pipe so that gives us our pipe the lengths of each of the cones dimensions
up here you can copy that if you want just quick run-through or the other
windows input calculator input values calculations okay this is for the input
values port timing and exhaust temperature so and exhaust port diameter
okay so the first one is for calculating the exhaust port diameter from the
exhaust port area so it’s just a handy calculator that makes it a bit easier
just put in the port diameter bore diameter sorry the curved when you get a
piece of paper and you put it inside the bore you you mark the piece of paper
then you measure the width of the port as I’ve explained in the video series on
the equations used in this and how to do that so you can have a look at those
videos if you haven’t yet this is just calculated chordal width which is the
width straight across that we used for the for the software purposes and here
then we took once we know how width and I port height we can add the radius
sizes of the ports again I’ve explained that in videos that will give us an
output of our port window area and then we get our port window diameter and
that’s the port window diameter at the piston okay and that’s at it in there so
that gives you a way to calculate that you can also put in a width and port
high here and radiuses etc to get a port window diameter if your outlet port here
that’s the outlet where the flanges on the head is not round so you can do the
same for that this calculator BMEP we can calculate from air engine kilowatt
rated kilowatts rpm or stroke length we can get our bmep bar pressure if you
know what the bmep is you can just add it in there and get the exhaust
estimated exhaust temperature so that’s to put the exhaust temperature into here
so that just helps you calculate that exhaust port timing calculator here to
put the timing value in stroke length Conrod length deck height top of
cylinder the top of the port exhaust port height itself again that’s the same
as that port height port height and from that we can hit the button and we can
get their exhaust port degrees in crankshaft degrees to put into here if
we’ve got the crankshaft degrees and we’ve measured it with degree wheel we
can put it in there put the stroke Conrod length in hit the button there
and we will give us the actual top of the cylinder and the exhaust port height
so you can actually physically measure those as a cross-check just to
double-check that we’ve got the timing measured exactly and properly
if you want to if you need you know if you need to because that’s fairly
critical to get these all sport timing measured correctly to put in the into
the software enough move on next one is the can calculators I’m showing this one
before in other videos but it’s just a side calculator if you got an expansion
chamber already on a bike and you want to measure the the angle of the
cone that you’ve got on a certain expansion chamber you don’t know what it
is the diffuser cone and you want to know what the angle is you might want to
change it or something then you can just get the diameters of the tip and the
base of the cone if you know what the angle is then you can get the center
length of the cone calculate that otherwise you can measure if you know
what the center length is it’s a bit hard to measure when the pipes are
complete so if you just put the side lengths in measure from here of course
you know the sideways length then hit the button you can get the actual angle
of the cone to find out what are these you might use you may not use it it’s
just it’s there another one is we can open a pipe and save a pipe so once we
put all the numbers in we can just save that name it if we want if we’ve got
different pipes you might want to open again and make some changes and then
calculate another pipe size so once we calculated their pipe we can then go to
flat cone plot opening here now this gives you the dimensions if you want to
draw on a piece of paper using a compass okay some software’s print this out but
it’s a bit big in some cases for an a4 piece of paper so unless you’ve got a
plotter it’s pretty useless printing it out so I’m gonna show you when I update
the software which will be a better way couple of things to doing it I’ll show
you how to do this with a compass and a ruler it’s very very easy then you just
draw the piece of paper you put it over a bit of sheet metal and then scribe
that down cut out your piece of sheet metal and you roll you can so if you
just want to make one cone you can put the base tip diameters of the cone in
the length Center length of the cone and hit the single plot and hit the
clock cone and gainer and get the values you need for a D B and C but we’ve got
four County L 2 L 3 L 4 and L 6 so in this case we just hit batch hit plot
cone and that gives us all of our cones L 2 L 3 L 4 and L 6 and that gives us
our A B C and D dimensions so we can just go like that
copy that put it into notepad print it out so that we can make a cones from
that so that just makes that a little bit easier and yeah the other thing
other option I was going to add is if we just if you want a straight header okay
if you don’t want to head over this L one
okay if you know an L 1 to be smaller and larger according to the port to pipe
ratio you just want a straight header I’ll just put an option in there you can
just click on that to make that a straight header because keep in mind
that that exhaust port the exhaust port window is the diameter from D 1 is from
taken from the exhaust port window something’s lost port outlet at the edge
of the head so and say if the exhaust port outlet here at the edge of the head
was larger we have a pipe that goes actually smaller and we don’t want to do
that so you can just click on straight header and that’ll just make sure that
the head is straight and that will make sure that the numbers or gel and yeah
that’s just a quick run-through I’ll do a more comprehensive explanation and
show you how the software works when I upload it it’s going to be free and
won’t be too far off so that will do it for now ok bye for now


  1. Would there be much difference in a mx chamber to a flat track one apart from header pipe length? Also anyway of knowing how much a dented chamber is affecting the bike? I am running a h1 Kawasaki with "drag" pipes in sidecar speedway and my center cyl chamber has been flattened from hitting ground and recently I cooked center piston.. I'm sure it leaned out coz of fuel line arrangement and running pump fuel but would this affect in anyway I might be overlooking?

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  3. So far looks fantastic!
    You don’t know how much we, the 2 stroke community, appreciate your hard work!!
    Thankyou so so much!

  4. Somehow, I hope my neighbors love your software as much as I do.. so excited to outfit weed whacker and chain saws as well. How do you roll the cone?

  5. Looking good!
    For the flat layout you need to add the sheet thickness (or technically 2 times half the thickness) to the diameter or the ID will be too small. Also a Cone Layout export function would probably be convenient for a lot of people there. I wrote some code to generate files for it a long time ago, I can mail it if you want 🙂

  6. I'm really looking forward to trying this software. Thanks a lot for your hard work! Hopefully my Yamaha FS1 and MX100 will appreciate the upgrades too 😀 .

  7. Any update on the software? Really looking forward to your final results!

    Thanks for all your hard work for the 2 stroke community!

  8. Thanks so much for going to all the trouble and time doing this I cant afford to buy a pipe design program and I'm into 2t big time wanted to build my own pipes for so long thanks again the videos are great as well

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