Some time ago I was at this electronic tech store that had loads of tech books.
The books weren't all about electronics thought. There were some on motorcycles and building expansion chambers.
There was loads of formula and higher math calculations to go thru.
It seems that you build a chamber for any "one" of the below:
1) torque
2) low end
3) mid range
4 top end
the torque tube just adds more torque all across the spectrum as soon as you bolt it on.
The others are "Peaky" meaning that they get a surge of power in that rpm band. Often the tuner will play with going up or down a couple of teeth on the front sprocket to widen that bost out to where it's more mellow or last thru the range of the gear to wind out.
But I'd say some math skills, algebra, and possibly some simple calculus could be used to lay out chambers for various cc displacements.
I went searching for Expansion Chamber design &fabrication data and found this:
Quote:
We now have a simple 2 stroke expansion chamber design program. FREE download here:
This program is not a part of MOTA, but it has been put together by the same engineers as a starting point for those wishing to begin from scratch. It calculates the dimensions for both double and triple stage diffuser expansion chambers from a few basic engine dimensions. The information used in the program's calculations was taken from the books ‘The Basic Design of the Two Stroke Engine’ and the book ‘Design and Simulation of Two Stroke Engines’; both books are written by Professor G.P. Blair of Queens University Belfast, and published by the Society of Automotive Engineers. You are well advised to read at least one of the books mentioned above, since they contain the author’s academic lifetime of knowledge on the two-stroke engine.
There are several coefficients used in the design of the expansion chamber – these are a function of the engine’s state of tune. Those used in this program have been chosen for petrol engines, and are in the range 50cc up to about 500cc per cylinder. It is doubtful these formulae would work on small capacity glowplug engines, since the exhaust gas temperature is much lower, and the engine speed is much higher.
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The page is at:
http://www.bevenyoung.com.au/mota.htm
It's a 1.5 Mb zip file so you'll need a free unzip utility like coffeecup's or others if you don't already have one. (CoffeeCup's free zip wizard is :
CoffeeCup Free Zip Wizard - Zipping and Un-Zipping has never been easier !
I downloaded mine and will unzip and look thru it later as I can.
I can imagine modeling these things to fit the bike with the least curves to make it buildable. Then there's the issue of a silencer cause it'll sound like a chain saw without one.
