I'll probably have 1'000's questions if I try this so here goes. Going beyond a muffler mod to a pipe( expansion chamber ) what does this take. Could you adapt a small bike pipe to a saw or is it all custom. I think I might want to get into some competion with my 2171 just not sure where to start, I have allready given the saw a muffler mod and woods port it runs great but I am addicted and want more now where should I start?
Saw pipe
- Thread starter Jim A.
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Four Paws
Addicted to ArboristSite
Building a pipe for a saw takes a solid understanding of 2-stroke operation and theory. The sections of the pipe do different duties to scavenge exhaust gasses from your cylinder and help 'overfill' the cylinder with a fresh charge. Jennings book is a good starting place - but is geared more toward GP race bike pipes. Start reading the theory and asking detailed questions from there. I am a newbie myself - and others have offered a LOT of help. Staged diffusers seem to work better on saws.
As far as port timing, you will need more radical numbers (than a typical woods port) to make your saw perform on a pipe. Specifically, longer duration.
timberwolf
Addicted to ArboristSite
I have seen a good number of pipes rigged from pipes off other stuff, often they work, but I have yet to see one work as well as a correctly designed pipe. All aspects of the pipe are governed by the engine design and desired output charicteristics. In both these cases there are substantial differences between bikes or sleds and production chainsaws.
troutfisher
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troutfisher
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blis
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The formulas on jennings book give good estimates for size of expansion chamber and such, but at best theyre only good quesses... But if you wish to use existing pipes for saw id look into moped's tuned pipe (mild one) and use it as base...
timberwolf
Addicted to ArboristSite
Bike pipes in general are very mild, they must be otherwise you would need a 10 range gearbox, the milder the pipe the less critical the length, but also the less potential it will have at the tuned RPM, with a race saw you want that to be pretty narrow but very intense band.
saws43
ArboristSite Lurker
pipe
forget bike pipes go to a contest and look at pipes in your cc class go from there I willhelp you if I can
forget bike pipes go to a contest and look at pipes in your cc class go from there I willhelp you if I can
timberwolf
Addicted to ArboristSite
Good advice about looking at what has been proven to work.
But the size of the saw makes less of difference in the pipe design then does the port timing and RPM. The size of the saw determines the header diamiter, after that it's the port timing RPM and fuel that determines what the pipe looks like.
But the size of the saw makes less of difference in the pipe design then does the port timing and RPM. The size of the saw determines the header diamiter, after that it's the port timing RPM and fuel that determines what the pipe looks like.
huskydave
Addicted to ArboristSite
I have been thinking and I believe a performance moped exhaust designed for a 50cc two stroke engine would make a good swap to a saw and im sure it would be very close to the right dimensions the bonus is they are tuned for topend power usually to get 5mph more out of the moped. I might try one out and see what if anything it will do. I may have to modify the header pipe to fit a saw correctly but I think for 50 bucks or so it's worth a try.
Chopwood
ArboristSite Guru
Personally, I would keep asking Brian (timberwolf) and John (saws43) questions. You might as well flush your fifty down the toilet instead of buying a scooter pipe. A lot of guys have tried. They sound cool, and that's about it. John was making saw pipes when I was in grade school, and Brian is as close to a mathamatical and theoretic genius as you can get.
romeo
Addicted to ArboristSite
Been there, they don't work. Even though its a high rpm pipe, its nothing like the kind of high rpm's you deal with in saws. Everything from diameter to cone angle to tuned length in all of the sections is wrong.
huskydave
Addicted to ArboristSite
Yeah I didn't think about the powerband. The saw will wind out a lot higher than a moped engine ever could so the expansion chamber will be longer and narrower at the end. What kind of price will a good saw pipe cost to be built by anyone worthy of the task? I have heard 300$ but for us hotsaw guys is there any discount hahhaha! who should I contact if you had the money hint hint. I just want the fastest 372 in my town right now.
Chopwood
ArboristSite Guru
Saws43 can't be too far from you.
cedarheaven
ArboristSite Member
Expansion Chamber
If you have the money I would contact Dennis Cahoon.
If you have the money I would contact Dennis Cahoon.
Crofter
Addicted to ArboristSite
300$ would have to be the very minimum. To do the calculations, layout, cut, form, fit and weld, fit to the saw and make proper supports is two days work unless you have the process really mechanised. If a saw is ported for pipe they can half the cut time but a work ported saw will not make near as big gains from pipe.
Crofter
Addicted to ArboristSite
I haven't heard of anywhere a person could get a top quality pipe custom made and installed start to finish for 150 Bucks. Fill us in!
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