Simple 2t explanation...

[zombie]

I just copied this from one of my replies. I impressed myself.

Re: new pipe
« Reply #17 on: Today at 11:00:40 PM »
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That's exactly what I mean. The red line rpm doesn't matter as long as the cruise rpm is within the powerband,

You want to be able to cruise the bike at what sounds good (never mind the tach), and still have some power left above that.
 The pipe, and the cylinder (in the big picture) have to match. You'll learn this as you read more. No offense.

Cylinders are ported. these ports are specific sizes. The size, and placement effect the rpm that the cylinder likes to run.
The pipe is nothing more than a pump. This pump pushes air backwards into the cylinder. (sounds wrong eh!)
This pump forces un-burnt gasses backwards into the cylinder to be burned (again).

That's how a 2t works. It's NOT in one stroke of combustion. It's in two strokes that repeat over again. Reading more on 2t cylinders  http://iheartstella.com/resources/manuals/tuning/Graham-Bell-Two-Stroke-Performance-Tuning.pdf
You will see what I mean.

The pipe creates a sound wave (echo) that pushes gasses back into the exhaust port to be mixed w/ the new vaporized fuel charge. since this is a MIX of hot gaeese, and raw (cool ) fuel it has an octane rating that can com-bust in a controlled manner. ie: no "ping".

I forget where this was going, and I don't want to look back...


Every PART of a 2t is linked to create a perfect balance. Putting a 9k rpm pipe on a 7k rpm cylinder does NOTHING but waste money. It many times makes LESS power than a stock pipe. (Latin so Stig can understand) the rest of you can use Zombie to English translate.
BUT you can take a 7k cylinder, and raise the ports, and widen the ports to make a 9K cylinder for free.



Now to be clear I HATE this guy (DIO SPEED DEMON) He's wrong as many times as right.
But to be sure... Follow Grams book, and learn the principals. If you really want more info on fine tuning ask me. Dio SP D. is wrong on a lot of things but I know better.
Porting, and pipes are like George, and Gracie or Ralph, and Alice.
They are no good without each other. 

Happy to help..."

[Stig / Major Tom]

Righto...but most times what you get is Gracie and Alice.
Buy 4 stroke and eat more chicken is what the Stig says.
Nobody likes listening to a neighborhood full of weedeaters screaming around in front of a cloud of codliver oil smoke.
Stig :-):-)

[zombie]

"Nobody likes listening to a neighborhood full of weedeaters screaming around in front of a cloud of codliver oil smoke."

So I see you've met my neighbors... Wait till I get the Triumph running. There'll be hell to pay \Open 12" x 1.5" headers don't ta know.

[ts1]

That is simple, but sometimes too simple.
Many new 2t scoots don't need an adapted response exhaust and can even run without any exhaust.

Aircraft engines (yes, exist as 2t too) are even more sophisticated. They may have valves and a wide power band.
Not to mention the 2t diesel with cylinder volumes measuring in cubic meters.

[zombie]

My favorite Marine diesel is the 2t, turbo charged, blower enhanced, direct injected Detroit Diesel v 12.

http://en.wikipedia.org/wiki/Detroit_Diesel_Series_71

Actually it is my favorite engine of all time. This also uses nothing like a pulse exhaust.

The only reason for expansion chambers is to increase power in what would otherwise be a low powered small engine. The idea is very similar to adding a lumpy cam/high rise intake manifold, and larger Carb to a four stroke engine.

Truth be told... An expansion pipe is a rather elegant solution for increasing power without modifying the engine.