All 2st Pipe/Expansion Chamber Shape

What is it about the shape of a 2 stroke pipe that makes it a top or bottom end power pipe?

How does the shape influence the power? Influence jetting?

I have a DEP pipe on my WR250 that seems good to me. I also have a slightly dented Gnarly I'm thinking about trying for the heck of it. I'm not a racer, just a woods rider. However, I don't want to mess up a good thing and have to fool around with jetting. I heard the Gnarly is a "bottom end pipe".

Thanks
Mike

Ohhh Mike, this is one with the 2 stroke engineers, it's all about resonance or pressure waves and the exhaust port, this is a pretty good article in explaining it but this where the famed 2 stroke engineers from motogp circa 500cc days and 250cc MX made their money in understanding.
http://www.motorcycle.com/how-to/ho...ambers-work-and-why-you-should-care-3423.html

Thanks. I see it's not a short answer. I found some videos on YouTube.

Good article, Ohmygewd.

I guess I have a more basic question: Can somebody look at a pipe, without knowing the pipe's characteristics, and say it is a bottom end or top end pipe?

Thanks
Mike

Hey Mike, you can by looking how the pipe tapers from both end of the cone, the length of the header section and the size of the cone, gradual tapering, longer header and smaller cone generally say's l'm more a torque pipe whilst the opposite are more HP with over rev.
Great visual example is compare the FMF Gnarly vs Fatty and then SST...then again, if correctly adjusting the port timings to one of these pipe's, you can 'tune' bike to the exhaust, then we get into the area of porting/timing and ignition= $$$

What are you after?

A mirical by the sound of, lol
Yes you can as omg has said you can also buy books and read about all the equasions and designs of pipes / porting two strokes.
Most say they are a simple engine design but f me sideways there is alot more too it the most give credit.
Also if your after top end you can start messing with compression ratios and port timing knife edging transfer ports and flowing corners slightly more... Or you can just ride and live without that ever coming up again.

Wholeheartedly agree Juicy, this is where the term black art of 2 strokes was coined...if you've got plenty of coin and can find one of these tuners, then you can have a barrels/heads and pipes custom made to whatever application your after.
4t engine tuning is far easier then 2t's in terms of extracting that 5%-1% of power.