pipe dimensions needed for pipe powerband analysis

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pipe dimensions needed for pipe powerband analysis

Postby Jaguar » 02:48 pm Nov 09 2015

I have software to analyze the extra power that a pipe generates and so I'd like people to take measurements of their pipe and submit it to me for analysis. I will post the different findings for each pipe which may give more technical insight into each for people to decide which pipe is best for their needs. I want info on the stock pipe, the different after market pipes, and the pipe for the SR (international version).
Just measure along the centerline as this drawing shows. Consider every place where the pipe cone angle changes to be a place for measurement of its diameter or circumference (you can use a string) and then measure the distances between each section. If you take your pipe off then also tell me the distance from the beginning of the pipe to the face of the piston. thanks
http://www.dragonfly75.com/moto/images/pipemeasure.png
Performance CDI -- KDX motocross mods -- the SR KDX -- expansion chamber analysis---> http://www.dragonfly75.com/moto/
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Re: pipe dimensions needed for pipe powerband analysis

Postby ohgood » 06:15 pm Nov 10 2015

I'll get started on this tomorrow... but don't you need two diameter measurements at each length , so you know the pipe is round?

the distance to piston should be the same, since the pipe flange and heads are normally similar?

or are you trying to map out distance from piston to each diameter change line?
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Re: pipe dimensions needed for pipe powerband analysis

Postby Jaguar » 08:18 am Nov 11 2015

on most bikes the distance from piston to pipe is around 40mm but I'd like someone to measure it to be sure. I'd do it but I'm without a KDX right now.
Performance CDI -- KDX motocross mods -- the SR KDX -- expansion chamber analysis---> http://www.dragonfly75.com/moto/
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pipe dimensions needed for pipe powerband analysis

Postby pumpguy » 04:43 pm Nov 11 2015

On my 97 KDX 200, the distance from the piston skirt to where the pipe connects to the cylinder is 55 mm ( 2.165"). This includes about 0.5 mm for the copper crush washer.
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pipe dimensions needed for pipe powerband analysis

Postby The Duck of Deseret » 04:45 pm Nov 13 2015

About a hundred years ago ( OK---maybe 39 years ago) Dirt bike magazine published an article based on a 'theory' about how to build a pipe for maximum power. It involved starting with the bore and stroke of your machine and then gave you dimensions for building your pipe. These dimensions entailed all the measurement factors shown in your diagram. I build a pipe for my Yamaha MX 360 according to their suggested dimensions. I installed the pipe and what followed must have been something to behold if you were hiding in the bushes watching the first test ride with the new pipe----------I'm not quite sure how I'd describe the results. Maybe I'll just say ""Wow"" .

There was no low end power but when the bike 'came on the pipe' it simply 'exploded'. The rush was so severe that the bike was unrideable when on the pipe and when it wasn't on the pipe it wouldn't pull the hat off your head.

So I guess what I am thinking is that your 'experiment' will be interesting -----and will probably reveal that the pipe manufacturers pretty much have this all figured out. But please do follow up and let's find out what comes of your experiment. It would be helpful if those that feed information to you also detail the year and model of bike they are measuring . Good topic!
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