Expansion Chamber

Sweet, nice lines, fits bike good..........

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"No such thing as a stupid question, just a stupid answer"

48cc Grubee Starfire Round Head......

Nice Bike Hookworm! I can tell that's one of Dean's pipes. How's the low end?

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Link to the Pipelyne tuned pipes
http://motorbicycling.com/f23/new-sc...-sale-189.html

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:

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.

My bike sounds just like a chainsaw... & I love it!!

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Check out www.VeniceMotorBikes.com

Mine too ...........

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"No such thing as a stupid question, just a stupid answer"

48cc Grubee Starfire Round Head......

One of my first dirt bikes was a Yamaha 90 enduro. When I put a mid range chamber on it the chamber had what looked like a 20 gage shotgun barrel
sticking out of it and it was LOUD !

I liked it but the dogs and neighbors didn't. So I go out to the sand and gravel
place and ride the begeez out of it. But after awhile I started getting headaches from it. (not to mention the neighborhood)

So I got this silencer that clamped on over the end of the tube and it cut the noise way down. It was a different world after that.

I'd mention that as these machines become more and more abundant that there will be those who complain of the noise they make. It may be prudent for us to consider chaperoning our own machines when out in public before authorities see an industry and $$$ traffic revenue in chaperoning them for us. (and at worst.......confiscating them because of the noise they make in public)

Alot of the guys on the Harleys pull the mufflers off them and replace them with straight (and very loud) pipes. Often they wear Tee shirts that proclaim
"Loud Pipes Save Lives". But it is right on the mufflers where it is unlawful to replace mufflers with straight pipes and may be a $10, 000 dollar fine. Still folks do it and ride thru the down town areas grabbing a handfull when the light turns green to make an echo chamber of the business sector.

I'm not making any judgement.....just the observation of the experiences I've had with bikes, the noise they make, and cops.

very cool setup!

looks good hookworm! lets see some more close-up pics , thats a nice exhaust shield!
"ride it like you stole it"

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I'll keep rollin "FileStyle"
"ever notice someone going slower than you is a idiot and someone going faster than you is a maniac" George Carlin

Well, I had some time while ago to unzip that Expansion Chamber Design Editor from the post above. pipe_dns.zip of 1.5Mb. It's straight foreward enough but I'm not sure about the horse power we're running with our projects. We may have to double the HP of our motors (or 10X) to enter so the software will accept it and at the other end divide the diameters and lengths by half or 10. So with all things being equal we may be able to get some workable figures it.

When you open it this is what it looks like:





The program is straight foreward and if you can use a caliper to take measurements on your engine and a piece of wire to feel into a port to a piston (and measure that distance with your caliper) you can probably use this software. The other values are probably in your owners manual or on a plate on the motor or housing. I would advise
trying to build the chamber as straight inline as possible so it can mount to the cylinder and toward the back on the frame running at an upward diagonal like dirt bike. It will be easier to build and mount and clear the pedals better. If you have a successful build, then a heat shield could be built of perferated sheet metal to cover the area where you inside leg would need a 1/2 inch barrier from the hot chamber.

This even lays out the profile for your expansion chamber for you at the bottom. Even sweeter is the Print button so you can print the chamber and spec's required to build it.

But since in Ahio we can only have 1 hp motors and this software wants HP values of 8 to 12+ I'll be "doubling and halfing" (or 10Xing) my math to walk the calcultions thru the editor. (then dividing by 1/10 the measurment it kicks out at the end.

Otherwise this is a slick little piece of FREE software.

What do we think about adapting the grubee long chrome muffler with an expansion chamber, it would look real clean and would fit in well with a cruiser bike.

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Theres more to life than MPG