For those who are interested in explansion chambers I'm posting a link to a small web site that has an animation of how it all works, with an expansion chamber. Mufflers only quieten the sound. shown are cut away views of carb, engine, and chamber. It's in color and watching it for a few seconds can explain much.
As I mentioned before there are expansion chambers for low range performance, mid range, (which I used) and high rpm range. There is also
what's called a "Torque Chamber" and it is what's shown in the site. (it has the parallel spacer in the tube where "range" chambers are made of all tapering sections of tubing. The torque chamber increases torque accross all RPM ranges. You don't feel a boost of power like you do with an RPM range oriented chamber.
I don't know if anyone downloaded the free expansion chamber design software I posted the link to a few post back. My little motor is just 30 some cc's so I'd have to multiply several times by the software's size thresholds to design a system and then reduce it by the same factor to keep it to scale.
But give this a look:
A RUNNING 2 STROKE ENGINE:
A two-stroke 
