Topic: The Strait Pipes Debate

[fdbrat]

Ok all Lets keep this strictly an "Ethos, Pathos, Logos" Debate.

RULES: If you make a statement, Provide evidence, the name author of quoted material, ect.

There are to many people on here contradicting one another. FACTS we need Facts.

If you have an opinion, State; In my Opinion...Ect.

EXPERTS and PROFESIONALS: Please state what makes you just that.

Yes there are Debates about pipes here, Yet here I hope to find people who can provide proof for their statements.

This is an all out Debate, no gloves.


To go strait or not to go strait, This Is The Question.

[devbear12]

i have info from www.cyclechange.net that states any exhaust mod with an appropriate intake/jetting mod is better than stock, but they have numbers showing a 4 into 2 into 1 is the best flowing exhaust for our sohc750s.  That is if you believe them?

[fdbrat]

Your link is bad my friend. Well at least on my end.

Very interesting.

So your stance is, an open pipe with proper settings of intake, Jetting and Can prove to gain more Performance.

I would like to see the results to your link. Seems to be down.

Assuming this performance gain is true, Some dyno results would be in order. How is This s effecting Gas millage?

[rachet]

DevBear12's link should of been... http://www.cyclexchange.net/ (he forgot the "X")

[Old Scrambler]

I think HONDA and Pops Yoshimura have already answered this question.

[mmtsquid]

I'm going to ask a dumb question...........
Why does a less restrictive exhaust require re-jetting?
I'm getting ready to install a Mac 4-1 on my cb550k, and just wondered how big a can of worms I am opening.

[Sporkfly]

My personal opinion is that there is nothing wrong with at least a simple baffle. If you can cut your sound a little you won't have to wear something ridiculous to save your hearing and you will still have a relatively free-flowing exhaust.



The fact is, you might as well call this an oil thread, but I'm interested to see others opinions and some facts as long as it doesn't get silly.

[754]

Well you set the parameters to make it tough to answer.

What is the intended use of the bike?, dont be general, be very specific.. quote sources as you may not be experienced enough to determine how to describe your actual riding..

[cafe750]

Aren't straits usually bodies of water? Like the Strait of Juan de Fuca?
See Below....
http://en.wikipedia.org/wiki/Strait





Sorry, but I had to...
Without going into too much depth, because I'm at work...

If it's straight pipes you're after, i.e. baffle-less, obnoxious, make you go slower without lots of motor work pipes, I'd have to say I'm not really a fan...but your local constabulatory official will be....

I do like the sound of a built open piped motor, but for most street applications, you'll actually get better performance with a little backpressure, at least a small restrictor tack welded into the collector.


Besides, if you ever take your bike for a long ride, that open pipe will give you a headache, and tire you out, because your body spends its energy trying to protect itself from the noise.

Just my .02

[754]

I hope this is gonna be a Straight thread..

[mlinder]

It depends entirely on what kind of performance you are talking about, and the machine you are considering putting straight pipes on.
Ask a less general question, please. It's like asking "glass or aluminum" without telling us what task these materials are being considered for...

[Caferacernoc]

Straight or open pipes are common in drag racing. They make the the most power but only over a narrow rpm range. That's because the single diameter pipe is only "tuned" over a single resonance. You see 4 into 1 pipes on road racers with common collectors so the individual cylinder pulses can scavenge the next cylinders exhaust and help filling of the combustion chamber. This is why the previous poster with the mac may need to rejet. It's pulling more air so it needs more fuel. So compared to a open pipes the 4 into 1 may have slightly less peak power but it has more midrange power over a broader range. And a 4 into 2 into 1 is better yet. Then there are the different types of megaphone mufflers and what not that also have similar properties over an straight diameter open tube.

[mlinder]

And, things like cam profiles, and port work, affect how different exhausts affect performance.
Just too many damned variables to give an answer to his question.

[chopstar500]

Qwote & fax & evidense: STR8 pipes are toadally bad-ace!!! Faux-hawks = not so bad-ace. Nuff said.

[mlinder]

Eye halve eh spelling chequer.

[KingCustomCycles.com]

I am an idiot savant with the gift of motorcycle repair.  I could list my credentials but that would just make me an arrogant dick with something to prove.

[I Zombie]

I am an idiot savant with the gift of motorcycle repair.  I could list my credentials but that would just make me an arrogant dick with something to prove.

love it
this is the only claim I can make, "I am an idiot savant"

[BlackMax]

like someone else already stated, the answer is...

Straight pipe:  will, assuming re-jetting of the carb, deliver more PEAK HP than a baffled design.  This really can't be debated, for 99% of setups.  

Baffled Pipe with some back-pressure:  will, for 99% of setups (there is always some exception that is simply a red herring), deliver more AVERAGE HP, and for sure average torque.

So, for drag racing purposes, where basically only peak power matters, or a very narrow RPM band, a straight-through design is best.  For applications such as street, and assuming two otherwise identicle bikes,  the one with  some back-pressure is going outrun the no back-pressure (straight through) bike.

The same principal goes for running a bigger CFM carb, or bigger/hotter cam.  What allows for more air flow, likely underperforms when max airflow isn't present.

[fdbrat]

I think you should go straiGHt ....to spellcheck 
It's that little button down there 


Well Mr billy profesor. My careles Mis Spelin is not the specificz we r In Serch of. I hope you could understand my Cave man spelling. Dear I do hope you know what I meent too say.

OK any way, I m looking for an expert that can provide decent Credentials, thus assuring his or her knowledge is not just an opinion.

BACKPRESSURE: Resistance to air flow; usually stated in inches H2O or PSI.
DELTA PRESSURE (aka delta P): Describes the pressure drop through a component and is the difference in pressure between two points.

OK I am hearing some back pressure, is OK. Why?

Can an expert who is not afraid to reply with his or her credentials explain a bit more about: sonic pulses, gas velocity, back pressure reverses, scavenging, valve overlap, jetting all relating to a formula.

This should not be guess work. This is a science, aaahhhhhhh

[cafe750]

Dude. What kind of riding, what kind of machine and what sort of modifications are we talking about. Otherwise, we can spout basic exhaust theory all day long, and it can be researched on the web.

There are soooo many variables, that concrete answers cannot be given.

There has to be a bit of effort on your end to do some footwork and research on this subject as well.

[mlinder]

I think you should go straiGHt ....to spellcheck 
It's that little button down there 


Well Mr billy profesor. My careles Mis Spelin is not the specificz we r In Serch of. I hope you could understand my Cave man spelling. Dear I do hope you know what I meent too say.

OK any way, I m looking for an expert that can provide decent Credentials, thus assuring his or her knowledge is not just an opinion.

BACKPRESSURE: Resistance to air flow; usually stated in inches H2O or PSI.
DELTA PRESSURE (aka delta P): Describes the pressure drop through a component and is the difference in pressure between two points.

OK I am hearing some back pressure, is OK. Why?

Can an expert who is not afraid to reply with his or her credentials explain a bit more about: sonic pulses, gas velocity, back pressure reverses, scavenging, valve overlap, jetting all relating to a formula.

This should not be guess work. This is a science, aaahhhhhhh

More than one person on these boards could expound on all of these at length. That's the problem. It's a freakin' books worth of data.
As I said, you need to ask a question that is more specific, so people that DO know don't say "fk it, I'm not gonna sit down and type for the next 3 days trying to cover all this."

[mlinder]

i don't need three days... i did that in about 2 minutes 30 seconds.   

It's not loading on my screen

[mlinder]

one too many loads on your screen i guess. 

Won't load independent of the forum, either.

[chrislib]

IMO straight pipes may sound nice but they wear on ya realllll qwik. I had my bike str8`ed for the end of last years riding season, after about 15 minutes it was old,the drone in my ears at 4-5k was unreal and probably dangerous as I could hear NOTHING over it.... but it sounded badass. Interestingly on my particular bike (stock K3) it had a touch more off the line grunt but felt soft in the mid rpm range (where 90% of my riding is done). Needless to say the cobbled baffle I had went back in. Funny but I am in the middle of designing a NEW cobbled up baffle to try and strike a better balance between noise and performance, I hope this incarnation (the 3rd or 4th) will meet my expectations (but probably not, I`m insanely picky with some things). my .02

[Kalamazoo]

Do... Whatever you want.
I mean why not?  If its going to F*** something up then whatever. Learn by mistakes right?

Do what you think looks cool, sounds cool, is cool to you, what makes sense to you. Dont worry about everything else.  At least thats what I did, helped my build tremendously.