Expansion Chamber

Hey, so what bike did you get this one off of (or what ebay auction?) I've got a 65cc tuned pipe coming that I'm going to try to fit to my 67cc HT, but its going to take a lot of cutting and rotating to get the exhaust routed properly. Should be better than stock at least.

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

Thanks for informative post, I have good idea how a two stroke egine works, but I was wondering about the benfits of an expansion chamber.

i want a 'how-to' instruction book.

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http://www.youtube.com/watch?v=MOQuj2XukHc

lestat101, the very last image at the bottom of that web site is an animation
of a 2 cycle engine equipped with an expansion chamber. If you watch it you can see what an expansion chamber does for a 2 cycle engine. Of course the web site has to make the assumption that a person may not know much about how 2 cycle engines work. It just takes a little time for the animation to load so you can see it work.

In the animation it shows how the chamber keeps more fuel air mixture in the combusition chamber that would otherwise be lost by a conventional muffler.
I've has several expansion chambers on my 2 stroke bikes.

Mr Larkins, I've seen those books you speak of but not recently. Lots of formula's and calculations. Then you only need a slip roller, some sheet metal, and light brazing or welding equipment. The free software I posted a few post back from IWT Racing lends itself to larger displacement engines, but by "doubling & halving system math" or Calculus one could calculate a basic performance profile expansion chamber and scale it to a family of engine displacements.

Something to look at:

Howstuffworks

that video of a running 2 stroke was worth a million words

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"You must cultivate the feeling that a warrior needs nothing"-don juan

I didnt like the noise level so I built a silencer that was almost double the inside diameter so I could get more packing in and give the ehaust more room to expand before leaving. MUCH quieter, and still sounds GREAT....

Attached Thumbnails

     

What did you use for packing material? I've got some fiberglass cloth left over from a ways back and I was thinking of sticking a little of that in my muffler.

I've found that most of the noise that comes from my bike comes from the cylinder itself, not the exhaust. Til my exhaust pipe falls off (again) anyway But since I lengthened my exhaust, I get a more snappy tone from the muffler, and I'd like to get rid of that.

An expansion chamber would be nice, but my wife is still mad at me for getting the bike in the first place, so yeah :-/

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http://www.jasonhight.net/videos/mot...etowork-sm.wmv

I tried using some fiberglass cloth on the old silencer and the larger one, and it was louder than the packing that came with the pipe. I ended up using fiberglass wall insulation packed very loosley and with the larger size made alot of difference. I just dont want to attract attention or piss off the neighbors....As for engine/cylinder noise I used tubing between every other fin to dampen that noise....

hmm, well considering my muffler has no packing right now, I guess the cloth should at least make a little difference

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http://www.jasonhight.net/videos/mot...etowork-sm.wmv