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anyone know whos photobucket page this is?

2K views 33 replies 12 participants last post by  Apok 
#1 ·
#5 ·
that is an xro akey very rare parts and no longer available,was made for the works teams only and phase 1,but i know to a few for sale,and you need the sump and pick up to use this set up.
 
#6 ·
I see, looking for a Ti header for a Yosh tri oval or an Akro

the header currently fitted I'm pretty sure isn't even for an SRAD, the mid pipe mount is about 2" forward of the the SRAD mount so its just bent over on both sides.. and its a 4 bolt pattern for the D&D can, I have no idea what its off but it doesn't leak and all but the D&D is just too loud and doesn't provide any back pressure at all, looking to give the neighbors a rest and get a little more off idle performance.

thanks guys
 
#14 ·
I was looking at this Akro but he wont ship it to the states

http://www.ebay.com/itm/160913316769?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2648

my friend had this one on his busa when he wrapped it up, doing a wheelie up a short 25% grade, blind left or go straight onto the freeway, my guess is he was going to go straight, unfortunately when he hit the crest the massive crosswalk paint spun the rear wheel hard when he was completely vertical, he tossed the bike into a concrete pole that had a Seattle times box chained to it, the bike came apart at the neck. MIRACULOUSLY the entire akro system survived only a scuff so minor the owner was wondering how long it had actually been there, that poor pipe suffered 2 totals, he rear ended a car that was doing 60 when he was doing 145, hospitalized but the pipe survived yet again..

it was a good sounding pipe as well, when it was freezing it would blow steam rings about 12 feet! tough as nails too... :)

 
#17 ·
what is back pressure? seriously? my verbage off? maybe its just an emissions thing?

and I dunno that I need a lot but I at least want close to what the bike was tuned for, the D&D is basically just a can straight through.. I know when I went from the dual system on my busa to a single Ti-Force system I lost not only MPG but low end torque, maybe it has something to do with unspent fuel I dunno really? but I'm willing to go back to stock form to see if this bike will have better performance off the line.

Suzuki manages it through the ECU and flapper valve on modern GSXRs but how they determined what they need I haven't a clue?
 
#19 ·
Anyone else, calling back pressure? What is it? I hear this term a lot, and it's a bs term, not a bad as a powerband, but striking similar.
Both really exist, but exist as something else, and the effects and dynamics are interesting.
I will give you a hint, it has nothing, absolutely nothing to do with restrictions, "straight through" as you called it, of a pipe, at least not in the terms you said.
 
#20 ·
Why does it have dual duplex canisters between pipe 1-2 and 3-4?

And twisted mister, unless you have a huge valve overlap like yamaha FZR you dont need backpressue (or alot of it).

The butterfly vales you see in the mufflters of modern bikes are for noise regultions i tought.

The yamaha FZR1000 for example has a butterfly valve in the collector to provide back pressue in the lower rpm's thus improving tourque.

The valve opens in the higher rpm's.

Come to think about it, lets say when you have camshafts which have a larger valve overlap then stock do you need some back pressure?

Do the duplex canisters also play on this?
 
#22 ·
Do you mean unstead of the larger canisters you see on the older exhaust they used 2 to have the same vollume?

My yoshimura TRS stainless steel exhaust has 1 duplex tube between pipe 1-2 and 3-4.

The older yoshimure exhaust have those canisters.



Should i also make another duplex tube between pipe 1-2 and 3-4 like the xro exhaust?

Bike will be raced (gsx-r 750/1100W).
 
#23 ·
You should likely leave it as is.
The balance pots/transfer tubes are there to enable one pipe to assist another in scavenging and extracting from the cylinder using harmonics from the other pipe. Your pipe was tuned to your duplex design. Also, that pipe was meant for a fully built 145+hp XRO Factory Superbike....
 
#24 ·
Some on, we did the srad Mikuni carb choke the other day, and it misconceptions, today its the infamous "backpressure". Tell me about it, what is it really?
The op says his D&D had no backpressure because it was "straight through"....is that true?
I used to know Dave Rash of D&D and watched him build pipes for me for new models....he never worried about "back pressure".....so tell me about back pressure.
 
#26 ·
""Positive and negative pressure waves wash back and forth through the length of the pipe and pipe and can design affects the timing of said waves and their arrival back at the motor. Good pipe design, among many other things, takes into consideration the design of these so as to ensure that negative pressure waves do not arrive back at the exhaust valves at periods of valve overlap and therefore bring with it burnt exhaust into the combustion chamber, and and in some cases into the intake track. Then, the next firing cycle attempts to ignite a mixture of of new fue/air and burnt byproducts.*""
 
#27 ·
Can I take a guess?

I know back pressure has something to do with resistance of exhaust gasses flowing through the system. You can lose power if your engine is not properly tuned for an aftermarket exhaust system. My guess is that the scavenging effect is too great on the cylinder and the engine runs a leaner mixture.
 
#28 ·
I'm not even gonna try :shifty :twitch
 
#29 ·
APOK........ITS NOT FAIR TO COPY AND PASTE MY OWN POSTS, GOOD ANSWER AND RESEARCH HOWEVER,....
The rest of the answer is that it is not relevant if is straight through or not, how big the bore is etc, its not back pressure......there is no real back pressure. What there is, is how effectively you can evacuate a cylinder, and how effectively you can tune the harmonics of the pipe to assist in both this and returning negtive pressure waves during periods of valve overlap (using combinations of collectors,total lengths,lengths to collectors,lengths of silencers,diameters,stepped diameters, etc.).
Now, the midpipe exup type valve is a different discussion entirely.
 
#31 ·
In 2t the power pulses help scavenge the barrel. I thought back pressure was only a problem in turbo cars. Too much back pressure can cause the impellor to stall. In n/a back pressure isn't as critical
 
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