Making your own exhaust (started)

[warped one]

OK so with all this credit crunch crap, I have no work to do so on Friday after standing around wiht my dick in my hand for 4 hours I decided to make a start.

1st of all I rolled a bit of 1.6mm (16 Guage) Stainless steel (St/St), Then tacked it together right down the seem at about 1inch inervals, then welded it all with TIG (cleaner) After that I made the end caps but need a 52 and 60mm hole saw before they can go on. But in the mean time im trying to decide the best way to create a bit of back pressure.

My curent idea is to make a sort of sandwhich of 1 plate with a 35mm hole in it 75mm in then a 50mm block of St/St followed up by another plate with a 35mm hole in it.

So would this work?

Cheers

Warped
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amnesia - Never in the history of usernames has one been more accurate. Warped indeed. You sir are a fecking oddball.

[SoND]

Why are you trying to create backpressure?
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[MaybeGuy]

[s44678]

What you are trying to achieve here, apart from trying to impress people by showing that you know some general engineering terms?

I imagine you would have to have a pretty good knowledge of fluid-dynamics (and engines) to design and build an exhaust that does anything other than make a loud noise. So why bother?

[Kickstart]

[Cigaro]

Have a pipe down the middle, sealed at one end with holes drilled in it.

This will create some backpressure and have a silencing effect too.

[proximity]

Kickstart is right, you do not need to bother thinking about pressure waves unless you are building downpipes. Just make it as unrestrictive as possible, unless you want it to be shit.

I built one for my zephyr, but only because i did an engine swap on it and couldnt get an exhaust to fit. Its straight through. I put a can on it though, so technically its just a mid section.

I think the rules for cans are along the lines of length/exit diam = loudness, can diameter = deepness?
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2004 Aprilia Tuono

[MaybeGuy]

oh right, i thought he meant a whole system.
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Kickstart wrote: Hi I tend to agree with Matt. All the best Keith

[Kickstart]

[warped one]

Skluff wrote

What you are trying to achieve here, apart from trying to impress people by showing that you know some general engineering terms?


A. Well what I am trying to achieve is a nice short can with a good note to it, but not to loud. The bike is a 650 V twin.

B. Unlike some people I have no intention of trying to impress people I have never met just asking for some knowledge, on how to build his piece and in engineering terms I make staircase's, handrailing, platforms and alot of other stuff. Which is why I put some terms in brackets for people who do not know what it is, I was on about.

So back on topic, should I make the internals as previously decribed or in some other way suggested by someone who knows what they are on about, also not really wanting to have to rejet.

Cheers

Warped
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amnesia - Never in the history of usernames has one been more accurate. Warped indeed. You sir are a fecking oddball.

[Kickstart]

Hi

I would just go for a basic setup. Cap on each end with a perforated tube between then. Match the size of the holes in each cap to your existing pipe and to the perforated tube. Wrap sound absorbing material tightly around the tube when you assemble it, and taking up the space between the perforated tube and the outer tube.

For real cheapness use loft insulation, but don't expect it to last that long. You can buy baffle packing material fairly cheaply (try a local motocross shop).

All the best

Keith
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[warped one]

So sort of like this?

Cheers

Warped
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amnesia - Never in the history of usernames has one been more accurate. Warped indeed. You sir are a fecking oddball.

[Kickstart]

Hi

Yep. The packing will compress and loose effectiveness over time but if you make it bolt together you can repack it easily (the old Allspeed 2 stroke exhausts held the baffle in with a large circlip which made repacking them a doddle).

Presume you will make up a pipe for it to slip on to the rest of the system with and tart up the outlet a bit.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[proximity]

I had a can with rusted end caps and the idea went through my head of buying endcaps to make exhausts. I know you can buy them because i've seen them on ebay. Im wondering if any manufacturers do them as spares, but saying that they wont be cheap.

edit: found this:
https://www.pjengineering.co.uk/products.asp?cat=10
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2004 Aprilia Tuono

[warped one]

Cheers for the help, guy's to you all.

I was thinking of using St/St swarf, for the packing as the is an abundance around the corner from my workshop, would it be ok to use this?

And would using this method mean that I would have to rejet? Or would it belike using my stock exhaust but with a deeper note?

And I was thinking that when the packing does become compressed and a bit shagged i'd just make another one, as the longest part so far is waiting for the old man to bring me home a 52mm hole saw.

But I do have a couple of CAD designs that are for a full system that would eliminate the dog poo curl from the back cylinder and bring it out the back of the fairing with 2 exit pipes. So thus bringing up another question of is there an optimal shape and size that I could fit in my fairing? Paint pics to follow.

Cheers

Warped

Cheers

Warped
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amnesia - Never in the history of usernames has one been more accurate. Warped indeed. You sir are a fecking oddball.

[Kickstart]

Hi

I know that some exhaust makers have used stainless steel wool as baffle packing (being long lasting), but no idea how effective it really is. Real small bits of swarf would be useless as they would just fall through the holes in the perforated tube.

There is a fair chance that whatever you do will mean having a play with jetting. You will change the flow of gases, but whether by enough to have enough affect that you care is another question.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[proximity]

It depends how restrictive your stock one is inside, its probably a load of chambers flowing back and forth.
Generally as long as its not a massive exit diameter it shouldn't be too bad, maybe copy the exit diameters of some of the commercial cans available for use without rejetting. I suspect though that they arent any different to any other race cans as generally bikes run ok with just an end can.

I'd be weary of a full system though unless you are confident you can get it right and the drawings you have a from a good source. An end can wont make much difference to your engine but a full system certainly will.

Consider having a smaller diameter exit pipe inside of the perforated tube aswell for further noise reducing db killer style.
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2004 Aprilia Tuono

[warped one]

So with this method will it be road legalish because the bike will be used everyday.

And the Dimensions for it are 135mm x 250mm, with the internal pipe been 52mm to 60mm.

Any quesses on how loud it will be? Youtube clip will be made when can fitted.

And Kickstart, who the hell do you know so much? Are you sure your not in mensa or something?

Cheers

Warped
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amnesia - Never in the history of usernames has one been more accurate. Warped indeed. You sir are a fecking oddball.

[Kickstart]

[chris-red]

Isn't the GTR injected? if so no jets. You may need a power commander but I doubt it, I haven't seen a big bike ever run crap (Carb'd or injected) by putting a straight through can on it.
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[warped one]

Nope mine is the 07 with the twin downdraft carbs.

And just a quick thing about marking the bolt holes, as i'm still using the bike, would I get a acurrite measurement from putting my divviders into the bolt hole and then makinga trinangle then turning it in to a circle? If anyone can understande that.

Cheers

Warped
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amnesia - Never in the history of usernames has one been more accurate. Warped indeed. You sir are a fecking oddball.

[warped one]

Yes, yes it is.

And if I undo them with the can just sort of drop off or is there a bit of the pipe in the can?

Cheers

Warped
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amnesia - Never in the history of usernames has one been more accurate. Warped indeed. You sir are a fecking oddball.

[Kickstart]

Hi

That will like depend on your specific exhaust. Could just bolt on or there could be a short stub that slides in before you can bolt it on.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[SoND]

[Rottweiler]

bit of a nobed comment by skluff cant he make an exhaust because he wants to ? cant see the point of the comment you made
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