Building a pipe

Chity_Avatar

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I want to build a pipe saw out of my SP80. What do I need to know other than the obvious 82cc displacement to make the expansion chamber correctly for the saw. I make part of my living as a welder and fabricator so the actual building isn't a problem. I have the abilities to hydro form as well.
 

Gink

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Jan 9, 2012
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Helmer, Indiana
You'll need to take some port timing numbers to plug in the online pipe building calculators. You'll need transfer numbers and exhaust port numbers. Are you just building a pipe for the stock timing or are you porting the saw for more durations?


BTW...Hi Al Smith!!
 
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Chity_Avatar

Mows his grass in 8 minutes.
Feb 15, 2013
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North Country New York
You'll need to take some port timing numbers to plug in the online pipe building calculators. You'll need transfer numbers and exhaust port numbers. Are you just building a pipe for the stock timing or are you porting the saw for more durations?


BTW...Hi Al Smith!!
Timing numbers I can get. It will be done on a bone stock saw for now. Maybe it will get ported at some point.
 
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I think what you will find is yes it will improve how that Mac runs but because of the design of a 10 series saw it will not perform like you think it might .There is no pratical way to raise the compression and what on earth a person does with that type design of transfers I have not one clue .

That thing is set at around 96 degree exhaust opening and you really don't want to take it any higher I wouldn't think .I'm afraid if you do it will never run worth a hoot on anything but a pipe ever again .

With nothing done to them except perhaps some widening of the exhaust port and possibley gutting the muffler they do just fine as a work saw .Maybe a couple more degrees of ignition advance .A race saw though I fear it's just an exercise .

Frank,how's the goat business .If you rode over to the Ohio flat track championship race this year I'm sure you got into that mess of Ohio 309 and I -75 exit 125 .I avoid it like the plague here of late .
 
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Gink

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There are several pipe building programs online where you can plug the info into to extract the dimensions of the pipe. Getting good information into the calculator can be tricky if your not sure what they are asking for. You can also reference some of the old math formulas and do it by hand. Pipes are fun to build and time consuming, and there is always something to learn. Here is one I did this winter, I had easily 50-60 hours in this pipe. And I still have some work to do to tune it and get some of the wrinkles out of it.

 
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A high angle return cone like that really intensifies the return echo but it limits the power band width RPMs .To run one it really takes a good operator to keep it on resonance .

My first experiance with a tuned pipe was decades ago when I was in the navy in Key West Fla .Half drunk on a Yamaha 250 .I was a Harley rider and had no idea how a 2 cycle acted when the pipe hit resonance .It unhorsed me right over backwards at about 50 MPH .Asphault fever .
 
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Adirondackstihl

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My first experiance with a tuned pipe was decades ago when I was in the navy in Key West Fla .Half drunk on a Yamaha 250 .I was a Harley rider and had no idea how a 2 cycle acted when the pipe hit resonance .It unhorsed me right over backwards at about 50 MPH .Asphault fever .
:rock:
 

Special Ed

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Jan 9, 2012
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Pipe building is interesting to me as well. My Copsey 7900 would be a decent candidate. I have thought about building a pipe with a sliding center, or belly, to experiment using different length chambers. Anyone here build a "slippy pipe"?
 
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Adirondackstihl

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Feb 6, 2013
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Pipe building is interesting to me as well. My Copsey 7900 would be a decent candidate. I have thought about building a pipe with a sliding center, or belly, to experiment using different length chambers. Anyone here build a "slippy pipe"?
I believe Gink built one for a member on AS. I think it was for a 390XP if I'm not mistaken?
 

Wigglesworth

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Jan 9, 2012
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Frank built the pipe on my 064. It's a work of art.

I'll snap some pics tomorrow. Here's a vid of it. The chain on it doesn't do it any justice. (Neither does the operator lol)

[video=youtube;ZiHPs5yhy0E]http://www.youtube.com/watch?v=ZiHPs5yhy0E[/video]
 
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