alimorg wrote:Wow - I never knew we had so many clever people on here, makes me feel quite thick!
that's why I love this forum so much..... not because it makes me feel thick (although I may be a little ), but because there's so many people here with so much knowlege. I often actually feel a little smarter if anything after reading this forum a lot of the time.
It's what a good forum should be about....... The sharing of knowlege/information and ideas between people with a common interest, not to mention a bit of friendly banter.
KR250 Tandem Twin (Naked)
KR1 Red/White
KR1S Track Bike (has been put on hold for now)
ZXR750 H1 (Winter project)
TwoStroke Institute wrote:OK let's clear up a few misconceptions.
Having made a 100 or so pipes or so I think I am qualified enough to speak on what makes a good and not so good pipe.
Software hit and miss? Well if you call dyno print outs shape and outputs corresponding to the simulated curves(but down 2-3HP due one a rear wheel and the sim a crank figure) 'hit and miss' then you might care to explain what is .
Software for pipes is like any other software ie $hit in= $hit out. However software will let you examine something that can't be seen the 'pressure time history' of the engine. Examining and making educted changes to optimise the pressure/time history allows a optimised ignition/carb/port/comp/pipe combination, works spot on every time.
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Hold on a min, hope this is not a poke at me, I was the first person to post anything relitively usefull and as I said it is what I have read and also there is an explanation after what I wrote, I myself canot say if the various software out there is any good because I have not used any, BUT as I did say its what I have read.
If this is a poke at me then maybe with the 100 odd pipes you have made maybe you would like to share some measurements with the people of the forum to help them out.
All I was doing is pointing out what I have read and another post on another forum about exhaust dimentions, cone software etc.
hiya ,all these links are great reading cheers kr1s stars & 2 stroke inst, =D> ,the more info the better, i dont think ile be using any computer programs for development ,just card patterns and copy to 0.8mm mild steel,then when ime happy do a few stainless ones(with the softest grade available)
alimorg ,yep i recon your right about the leon moss pb article was a ts250 ,back in the late eighties,think he used t work for ledar but do alot himself at home
TwoStroke Institute wrote:OKSorry Jan but cone pipes with distinct and defined ends to each section consistently out perform 'smooth' stamped or hydroformed pipes of the same dimensions.Dimensional accuracy is difficult also with hydro forming.
on this I agree. I think we are thinking the same, only difference is I'm thinking it in Dutch and have to translate it
My ultimate goal is to die young as late as possible !
No kr1 not a poke you at all. Just pointing out that was is not remotely correct, and info on internet forums many times isn't accurate or come from someone who has experience.
Fred problem with going in blind is, first set may not work as planned, software just cuts down your margin for error. Stainless is shite to work with and unless internaly purged when welded. If it's not purged it leaves nasty 'weld boogers' on the inside of the pipe.The 0.8mm mild steel is the go, as stainless has another nasty habit of raising the rpm at which the pipe comes into phase.
Jan as someone who spent 6 months in Holland I still know this one
De houten schoenen, Houten hoofd, zouden niet luisteren
( Not sure if that translates.)
[quote="TwoStroke Institute"]No kr1 not a poke you at all. Just pointing out that was is not remotely correct, and info on internet forums many times isn't accurate or come from someone who has experience.
quote
Thats ok, just seam a little poke, obviously you have read similar posts then, ive been looking into 2 stroke designs for years, got a good understanding, there is know way I could design some from scratch I get lost with all the figures, I know what each chamber does and effects of changes etc but there is one thing I just cannot get my head round and that is stainless pipes, what is the reason that two pipes made exactly the same both good quality but one in mild other in stainless why the stainless ones wont perform as good? Just cannot get my head round that one.
I just cannot get my head round and that is stainless pipes, what is the reason that two pipes made exactly the same both good quality but one in mild other in stainless why the stainless ones wont perform as good? Just cannot get my head round that one.[/quote]
this is a good question,i was going to ask the same myself (heres my stab in the dark ,wild guess Mild steel is softer so will resonate at a lower frequency,stainless is harder, resonating slightly higher )
my first project on this wont be desighned more of a measured copy
TSI What program do you use for your chamber design?
I have in the past had a play around with the demo version of MOTA which always includes a gradually expanding primary pipe all the way to the chamber in the design. How much of a benefit is this?
If it were for most bikes this wouldn't be any real issue, but for my Tandem Twin this style of primary pipe would be very difficult to make fit on the rear cylinder. Is there any way to compensate for this when designing my pipes?
KR250 Tandem Twin (Naked)
KR1 Red/White
KR1S Track Bike (has been put on hold for now)
ZXR750 H1 (Winter project)
Stainless takes longer to heat up and the heat is localised, if you try to drill a hole in stainless sheet you become aware of 2 things.First if you use high speed the drill goes blunt and it get very hot under the drill but not much anywhere else. In short heat doesn't travel through the pipe as fast as with mild steel.Good stab though fred. A stainless pipe should be a bit shorter to compensate.There is a flip side where you come back on throttle after braking, it hasn't lost as much heat as a mild steel. Titanium pipes are different specs to mild steel.Not that they don't work as well they just take longer to heat the whole pipe up, same with chrome/nickel plating and heaven forbid these stupid 'heat resistant' coatings.
The demo of mota won't tell you much and a tapered header is the only header to use,benefits hmmm maybe 5HP per cylinder.I would have to see the pipe routing to give any advice.I have designs that tend to work with certain rpm/port/carb specs.Then it's just juggling the pressure peaks and troughs around with the ignition and pipes to achieve the output curve shape required to match the gearbox.
Jan I learned the saying relating to a Dutchman's famous stubborn streak "He has wooden shoe's, wooden head and wouldn't listen"
TwoStroke Institute wrote:
Jan I learned the saying relating to a Dutchman's famous stubborn streak "He has wooden shoe's, wooden head and wouldn't listen"
I thinck you 've forgotten a few words then , it should look like
Hij heeft houten schoenen, een houten hoofd en wil niet luisteren
My ultimate goal is to die young as late as possible !
i have used a screen measurer to scale 2 pictures of j lomas pipes,i know it`s not perfect,but scaled 2 pics and averaged the measurements,i now have a dfx file for the laser cutter to cut the 5 cone segments,from the base of the downtube
sideview 57 dia-206 long to 103 dia
103 dia-68 long to 118 dia
118 dia-87 long to 112 dia
112 dia-50 at top ,69 long at bottom to 91 dia
91 dia -120 at top,136 long at bottom to 24 dia
ime going to cut 1.5 mm galve templates to make paper templates at home(can post) or cut at home,and use the dfx file to cut some 1mm mild steel at the mo as a first trial .these will be tig welded to standard headers,anyones views are more than welcome .oh and i wont be going into mass production.lets see how it pans out tho ,cheers fred
Not sure what ya mean here Fred, if you're talking about the machine you use, just a normal roller, I've pounded one out by hand once but that was not fun and I wouldnt recommend it. If you mean how you draw the cone on the template / drawing, it's gotta be done properly with the curly style layout (technical term that... must be the beer)
), but because there's so many people here with so much knowlege. I often actually feel a little smarter if anything after reading this forum a lot of the time. 
Mild steel is softer so will resonate at a lower frequency,stainless is harder, resonating slightly higher 
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