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Re: Exhaust

We are talking about home made exhaust here. None of this have them do it. How would you make it from scratch like a hardees biscuit. What materials for exhaust and to bend the metal into shape.
 

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One method is to get some reject bent tubes from an exhaust shop in the right diameter, along with some straight sections. Then cut and paste the pieces to build something that fits.

To build a nice system at home from straight sections fo tubing, with no dedicated bending tools, can be done I suppose but it's not easy. Filling tubes with sand, maybe heating, bending around jigs, not my idea of fun. And then you'll still likely have to cut and paste to make it work. You might be able to come up with a compression bender but anything other than shallow bends will look like crap without filling the tubes first.

Or you can get really labor intensive and do wedge cuts on small sections of tubing to make your bends. Lots of cutting/welding involved.

Or you can try to modify an exisitng system using any combination of teh above methods.
 

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It's difficult to bend tubing without kinking it on any kind of affordable bender, though I have seen claims of success filling the tube with sand, ice, etc. and using a cheapo bender from harbor freight. I haven't tried it but am skeptical. You need a mandrel bender to do it right and the cheapest ones I've seen are very spendy.

I think the most reasonable approach for the home builder is to tig weld it up out of prebent elbows and u-bends available from places like Burns Stainless or Stainless Works. Bends that aren't available are "fabbed" up out of "pie" sections cut from what is available. I've spoken with Doug at ARC fab and this is what he does.

I've done a little bit of it and it is very putzy on the bike, cut and fit, cut fit, grind fit, oops throw that piece out start again, kind of process.
 

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if the process was fun you wouldn't be asking the question, because everyone would do it!
But seriously, the end resualt that you did it yourself and learned is what makes it ...uh...fun. Noticing all the bikes here with the same exhaust and yours stands out is fun. having people ask where did you get that exhaust and your reply...i made it..is fun!

you can do it, there are enough resources here to help you sort things out if you just want to learn...i have been thinking of doing this myself this winter.
I will buy some prebend stuff from burns stainless, and assemble it myself, i may actually get a friend who is a master welder, specializing in ...uh..specialty metals.

good luck,
RB
 

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Depends on your definition of fun. :p

Could be fun, won't be easy for the uninitiated, but rewarding... possibly... or totally frustrating. Also will need some fairly spendy tools like something to cut stainless accurately, various grinders, clamps, and a preferably a tig welder, back purge set-up, blah,blah...
 

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Whatever guys, Ive built 5 motorcycle exhaust systems and about a billion header-back car exhausts and let me tell you, the first 2 where not fun but now I love it! People have already told you the basics, its pretty much get ellbows and cut and weld, but thats not the best help for a beginer, heres a step by step of what your going to want to do:


first draw something up, I saw the picture of that flat track racer but your going to have to go up to YOUR bike and work from there, sketch out the basics, engine with exhaust ports, frame wheel swinarm etc, basicly the stuff you have to work around. then photocoppy that basic picture of your bike, use the photocopies to draw up different exhausts until you find something that flows with the bike

now its time to draw out the actualy pipes, since exhaust is kindof an art, not a science (dont argue with me) you dont need to do a crazy laid out to scale dimensioned drawing, just the basic routing of the pipes, it helps to get like flex exhaust tube to hold up.

ok now youve got your design, go order tubing, elbows straight etc try to get a variety of bends, and radius, avoid "J" bends and long "U" bends, if your buying strait tube its kindof pointless to get thoes extra strait secions on your elbows. stainless or mild steel if you plan on just coating in flat black (probably a better idea for your first exhaust) since it costs less.

ok youve got your tube, now here are the 2 tools youll need: chop saw and a welder (prefferably tig, mig will do, an arc welder will also work but is unfavorable) < if your using anything besides a tig welder or are untrained in welding let me know and ill tell you the right stuff to get/do. but from here on out ill asume you can weld halfway decent.

fabricate the hanger for your mufflers first, get them into position and attached onto the bike, make sure that the inlet on the muffler isnt obstructed (make sure the pipe can reach it)

start with your header flange, (the one that goes into the engine) either custom made, ordered from somewhere, or cut off your stock pipes. now comes the long boring part, using thoes bends cut out sections that corospond to the bends you want for your pipe, this is where that flex tubing comes in handy, you can make a sectoion out of it and hold it up to your elbows for an acurate measurement.

now heres the important part do NOT seam weld each piece as you cut it, you want to tack your exhaust together (a small spot weld, two or three per seam sould be fine) before you weld the whole thing shut. if possible starting at the header do your tacking on the bike, either get a friend to hold the tube in place or rig up some kind of clamp, if you have access to a MIG welder tacking is much easier.

if your concerned with keeping the pipes equal length, cut a piece of wire and fallow it around the first pipe, and use the same piece of wire to measure the second pipe

basicly work your way back to the muffler in this fashion, tacking everything together, do not seam weld a single piece until you can see the entire system on the bike and fitting in place.

when you start seam welding, especialy with stainless steel pipe, dont do entire seams at a time, do a couple inches here then skip to a different seam, this will keep the metal warpage to a minnimum.

If you get finished and think your welds look awfull, chances are your not going to want to grind them down, if your not confident in your welding ability chances are your welds dont penetrate as much as youd like, grinding them down is going to kill the strength that they do have. consider wraping them with ceramic coating or at least painting them to draw attention away from the welds.

thats about all i can think of right now, feel free to email/pm me with any fabrication questions (OP or anyone else whos reading) I love talking about this stuff. good luck and keep the custom work coming!
 

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Langanobob said:
Great explanation and thanks for taking the time to post it. I noticed you didn't mention oxy-acetylene as a possible method of welding the tubes. Any reason for that?

I may be tackling an exhaust modification and using your info I think I can do it.

Bob
UM, I think that is pretty much used for cutting torches not welding.
 

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oxy-acetylene is deffinitly an option, (its used for cutting yes but also for Brazing, a form of welding) Ive actualy never done any oxy-acetylene welding, ive always had a machine welder around and only used oxy-acetylene cutting rigs, but its deffinitly possible if thats what your good at, just make sure you dont warp the pipes, that kind of work puts out a lot of heat and its good to take your time and let things cool (not quenching them) A great example of brazing is on this tank made by Billy Lane:


Ok correction, Oxy-Acetylene welding is actualy a lot cooler than other types, just trying to keep my facts straight
 

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I started mine by removing the cat. If you look on the floor you can see a couple of 90 degree stainless bends. I used 45 degree bends and some straight pipe for the cat removal. They are pre-bent stainless elbows, mandrel bends, no crimps. I want to move one of the stock cans to the other side and when I find a couple mufflers I like I'll swap those out too.



 

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I've done a number of 4-stroke and 2-stroke exhausts in mild steel.

Oxy-acetylene welding is perfectly fine for mild steel tubing.
Just like any other type of welding, it requires significant 'seat-time' to get skilled enough to make good welds.

You can get mandrel-bent mild steel tubing from JC Whitney or Bassani, there are other vendors as well.

You can get megaphones from these guys, and I think they have mandrel bent tubes as well:
AirCone Exhaust systems
+1 (702) 566-1077
+1 (702) 566-0232 Fax

Mandrel bent stainless tubes are quite a bit more expensive, and harder to work with, but do look prettier.

Burns Stainless has a large selection, and will fab custom stuff as well.
They're not cheap, but their quality is top shelf.
www.burnsstainless.com
 

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What would be the process of creating some custom headers. I have the cans I want to use, supertrapp

I want that flat-track look.
Hi, you have a very interesting and rewarding project.
There are lots of ways to bend tube. Fill it with sand or salt etc, etc ..One must decide their own path to success.
One good do it yourself path is via iceengineworks.com .... it may cost money but making it your own always does.

The Jay Springsteen Harley Flattracker is an amazing motorcyle!

Another approach is using your cad skills (or newly learned skills) to create the model for a pipe bender to ply his pipe bending magic on ....

You should also read about exhaust header lengths ... in the 70,s when I was still crazy, we learned that 41 inch exhaust header length was a target before the silencer entered the picture.

Anyway, the worst thing you can do in the process is lose some horsepower .... and if you ride the street, who really cares ...

I have just embarked on building an oil cooler from either rectangular or square copper tubing ... very cool stuff .... and this will replace the unsitely blob of plastic and aluminum that hides my horizontal cylinder ...
 

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