Yamaha R6 Forum: YZF-R6 Forums banner

1 - 20 of 61 Posts

·
Registered
Joined
·
79 Posts
Discussion Starter · #1 ·
I was wondering if any of the after market systems out there have this valve or do they all just do away with it?
 

·
Phi Phi K A
Joined
·
823 Posts
I have not scoured the earth trying to find a pipe that keeps it, nor would I try. But, I do not think there is one that retains it. Why would you want to? And if you say "backpressure" I will ignor this thread. LOL
 

·
Registered
Joined
·
372 Posts
I havent seen any when I was looking for a slip on but then again I wasnt looking for one with it.
 

·
I <3 my R6
Joined
·
49 Posts
I have not scoured the earth trying to find a pipe that keeps it, nor would I try. But, I do not think there is one that retains it. Why would you want to? And if you say "backpressure" I will ignor this thread. LOL
Well you are obviously convinced that it creates no back-pressure. Why do you say this? Just wondering. I'm on the fence about the whole thing. It *seems* to help the low end on my bike, but I also have the 05 header and stock can.

If not for back pressure - what do you think it is for? Noise reduction? It does certainly reduce noise - but is that truly the intended purpose of it?

All other 600s and many 1000s have a similar valve - do any of them actually work to create back pressure?

Just wondering what you know about this, I haven't seen much good info.
 

·
Registered
Joined
·
45 Posts
i got an error code that said it was stuck...and it was...

so i took the cables off.

no problems since

(100% stock)
...for now.
 

·
Phi Phi K A
Joined
·
823 Posts
Well you are obviously convinced that it creates no back-pressure. Why do you say this? Just wondering. I'm on the fence about the whole thing. It *seems* to help the low end on my bike, but I also have the 05 header and stock can.

If not for back pressure - what do you think it is for? Noise reduction? It does certainly reduce noise - but is that truly the intended purpose of it?

All other 600s and many 1000s have a similar valve - do any of them actually work to create back pressure?

Just wondering what you know about this, I haven't seen much good info.
I really wanted to avoid this whole conversation so I will try to be as succinct
as possible.

Yamaha says that it is there to create "backpressure." Which, they say will help mid range power. After the dyno runs that I did with and with out it, I found differently. I do not want to get into an argument about it so I will say this, MY bike get more power(even in the mid range) with out the exup. There is a reason why ALL race teams do not utilize this stupid mechanisim. Further, there is a reason why no after market off road exhaust uses it either. The reason is becuase all of the testing and research they do have found that it inhibits the power across the board.

To answer your question about why they put it there. I can't say for sure. Maybe to adhere to emission restrictions and noise ordinances. It has to be something to do with adhering to some law or ordinence or something. But, again, I do not know for sure. I do know that they put a real good spin on it.

I do not want to get into a big conversation about exhaust theory and backpressure. But I will say that it only "seems" to help down low. At least this is what I have found on my bike and dyno runs.

paytheon said:
Removing the EXUP leads to more problems than its worth computer wise. It doesn't hurt to leave it alone.
Removing it does not effect the computer at all. The ECU tells the servo motor to open and close the valve based on throttle inputs and speed and rpms and so forth. It does not receive any information back from the servo itself other than to tell you if it is working properly or not and if it is plugged in. So, DO NOT remove the servo or unplug it. Only remove the cables and you will have no problems or error codes or anything like that.
 

·
VVVVVVRRRRRRRRMMMMMMMMMMM
Joined
·
221 Posts
Well, I guess my next question is why do the Saleen Mustangs come with that same servo.. along with many other high end sports cars... Oh, and I would think.. maybe I am dumb for thinking but more spent exhaust left in the combustion chamber would lead to more NoX emissions because of the heat left in the cylinder by this exhaust which is actually worse for the environment.. Of course this is all theory. I haven't done a sniff test on the exhaust.. but back to the original theory for the servo.. it wouldn't be for emission reasons. Unless you have a turbo alittle back pressure is a good thing in most cases. I forgot usually they try to match back pressure with cam gap timing for the scavenging effect.
 

·
Phi Phi K A
Joined
·
823 Posts
Well, I guess my next question is why do the Saleen Mustangs come with that same servo.. along with many other high end sports cars... Oh, and I would think.. maybe I am dumb for thinking but more spent exhaust left in the combustion chamber would lead to more NoX emissions because of the heat left in the cylinder by this exhaust which is actually worse for the environment.. Of course this is all theory. I haven't done a sniff test on the exhaust.. but back to the original theory for the servo.. it wouldn't be for emission reasons. Unless you have a turbo alittle back pressure is a good thing in most cases.
This is exactly why I did not want to talk about this.

Good luck with all your knowledge and experience Oldkey. Keep the thing, don't keep it, I don't really give a shit. I posted MY results from ACTUAL dyno tests. And my opinions about why race teams and exhausts don't use it.

I have said it before and I will say it again
Both statements are incorrect. Mufflers often (if only slightly) reduce power. When using a typical freeflowing (aftermarket) exhaust "backpressure" is nonexistent. The term "backpressure' is very often misused or misunderstood. Exhaust theory is a bit too involved to fully explain here. But no matter how much genius engineering goes into an exhaust design, it always comes down to testing (on a dyno). If it makes more without a muffler, so be it.

Done with this thread.
 

·
VVVVVVRRRRRRRRMMMMMMMMMMM
Joined
·
221 Posts
Dude I didn't mean to piss you off.. but I think you do need to keep in mind that a dyno is a calculated measurement of your hp/torque. It is not the true 100% measurement. There might have been elements that might have effected your dyno results. It's all based on formula's... without going into great detail about that I would just say... There is a reason for it or they wouldn't include it.. because lets face it.. its more money for yamaha to put that part on there.
 

·
I <3 my R6
Joined
·
49 Posts
Thanks Noleman - that is exactly the kind of info I was after.

I think you make very valid points and you have personal testing that backs it up.

When in higher RPMs in 2nd gear, letting off and then getting back on it quickly often times causes the bike to hesitate really bad. I'm pretty convinced its the EXUP doing some stupid shit where it closes up or something.

Ive had my eye on the LeoVince for a while now and the EXUP was a slight concern of mine - but after your very insightful points - I'm no longer worried about it.
 

·
Registered
Joined
·
59 Posts
Remove the mid and lower fairing from the motorcycle.
2) Remove the Noise Reduction Valve cables from the
muffler. Remove the noise reduction valve cable clamp
from right side rearset. Remove the muffler from the
motorcycle.
3) Unscrew O2 sensor from the exhaust system.
4) Remove the exhaust system from motorcycle.
5) Remove the bracket holding the rear brake reservoir to the
frame.
6) Remove the two bolts holding the noise reduction valve
motor bracket to the frame. Remove the noise reduction
valve motor assembly by pulling it out of the right side of
the motorcycle.
7) Disconnect the Noise Reduction Valve control cables from
the Noise Reduction Valve motor. You must leave the
Noise Reduction Valve motor electrical connector in place
or an error code 17 will display on the LCD screen on the
dash.
Graves call it " Noise Reduction Vavle "

So ?? what do you think ?? Back pressure or noise reduction ??

I know the F430 and the GT3 both have a vavle also in their exhaust and I doubt it is for back pressure, but who knows? cars a different?
 

·
VVVVVVRRRRRRRRMMMMMMMMMMM
Joined
·
221 Posts
Good question.. and honestly I am not sure why its there. I have theories from automotive school that I remember thats all. I do know that they setup exhausts to be narrow enough to have a suction effect on engines. Most people think bigger is always better. Based on what I was told from Nascar engine builders you want an exhaust setup like intake runners. They want the exhaust to have a suctioning effect on the cylinder. So when the exhaust valve opens there are still spent gases moving down out of the exhaust. This will create a scavenging effect thus moving more spent exhaust out of the combustion chamber and leaving more room for clean air and fuel. This equals more power! Now, how does this valve apply to this theory? Well, I think they made the exhaust bore bigger so that the engine will not have a bottle neck effect at higher rpms. How do they still achieve the scavenging effects without having some type of radical exhaust? Keep enough volume in the exhaust to keep this suctioning effects going under any situation by regulating the flow. Now, moving on to why they do not use these valves in racing. Let's think about the overall rpm ranges of these bikes are in during a race. Probably keep in a 9000 rpm range. (This does not mean 0-9000rpm. I mean throughout the race above a certain rpm lets say.. 8000rpms for our bikes.) 98% of this race is going to be above this range. So, having the money and technology lets have the exhaust tuned for these conditions. The exact bore ect. Lets face it more things that can break will break and also if you can get away with less weight anywhere on a race bike its a good thing. Anyways our exhausts have to be practice for daily use on the street. We cannot go around town at 9000+rpms. So, this is my reasoning for the valve. Think its bogus? In my opinion, physics are on my side. Ask yourself why they did the 2008's with the cool new variable intake. Same principle I believe. I would love to hear other theories if anyone has any. Bobby
 

·
Redline.......White Light
Joined
·
751 Posts
I think Noleman is rightful to say what he found. That is great, looks like he races, probably had more hp up top, didn't pay attention much down low. I have access to a dyno 24/7, he pays for it. Upon other thread discussions with noleman he has been unable to provide me with an accurate a/f reading, which is EXTREMELY common if doing a dyno run. :dunce: SO, this is my KNOWLEDGE and is not a theory. I am not BY FAR the smartest person here or the most experienced. I DO have a masters degree in electrical engineering and started out wanting to do SOMETHING in fluid dynamics. SO with that said, here is how it works with heated exhaust gases, i will give you a BRIEF overview, if you want the full story pm me.

You want exhaust FLOWING, HOT gas cools.....causing it to slow in the pipe because cooler air is more dense and that makes it harder to move. In an effort to keep these gases HEATED without causing turbulence is SLOW IT DOWN. That can be acheived by a small pipe, INSULATE THE PIPE, or.......a butterfly valve(exup). A large pipe works when you are in HIGH rpm, when flow rates are up. This is where exup sucks, it slows down the gas at high rpm. The right size exhaust pipe is going to be dependant on the flow rate (volume rate, which is related to RPM and engine displacement), exhaust velocity (again related to RPM), exhaust temperature (as well changing, and as high as 2,000F)

Mark my words, look at any FULL RACE setup, there is a loss at either low end or mid range, with any motorcycle OR car. It all depends on what Throttle position/rpm you are at most of the time. If you are a racer.....full exhaust is for you. If you ride the 25mph downtown roads to show off for girls...... Stock is for you.

My .02.
 

·
R is for respect!
Joined
·
1,623 Posts
I think Noleman is rightful to say what he found. That is great, looks like he races, probably had more hp up top, didn't pay attention much down low. I have access to a dyno 24/7, he pays for it. Upon other thread discussions with noleman he has been unable to provide me with an accurate a/f reading, which is EXTREMELY common if doing a dyno run. :dunce: SO, this is my KNOWLEDGE and is not a theory. I am not BY FAR the smartest person here or the most experienced. I DO have a masters degree in electrical engineering and started out wanting to do SOMETHING in fluid dynamics. SO with that said, here is how it works with heated exhaust gases, i will give you a BRIEF overview, if you want the full story pm me.

You want exhaust FLOWING, HOT gas cools.....causing it to slow in the pipe because cooler air is more dense and that makes it harder to move. In an effort to keep these gases HEATED without causing turbulence is SLOW IT DOWN. That can be acheived by a small pipe, INSULATE THE PIPE, or.......a butterfly valve(exup). A large pipe works when you are in HIGH rpm, when flow rates are up. This is where exup sucks, it slows down the gas at high rpm. The right size exhaust pipe is going to be dependant on the flow rate (volume rate, which is related to RPM and engine displacement), exhaust velocity (again related to RPM), exhaust temperature (as well changing, and as high as 2,000F)

Mark my words, look at any FULL RACE setup, there is a loss at either low end or mid range, with any motorcycle OR car. It all depends on what Throttle position/rpm you are at most of the time. If you are a racer.....full exhaust is for you. If you ride the 25mph downtown roads to show off for girls...... Stock is for you.

My .02.
great write up and some damn good info in there.
 

·
Premium Member
Joined
·
18,783 Posts
One last time, removing the EXUP will effect the computer if you removing. You "will" have an error code message if you removed the EXUP. Anyone saying you won't doesn't know what they are talking about. Can the EXUP be removed and the computer problem resolved? Yes. But it's a headache to do so.
 

·
VVVVVVRRRRRRRRMMMMMMMMMMM
Joined
·
221 Posts
I think Noleman is rightful to say what he found. That is great, looks like he races, probably had more hp up top, didn't pay attention much down low. I have access to a dyno 24/7, he pays for it. Upon other thread discussions with noleman he has been unable to provide me with an accurate a/f reading, which is EXTREMELY common if doing a dyno run. :dunce: SO, this is my KNOWLEDGE and is not a theory. I am not BY FAR the smartest person here or the most experienced. I DO have a masters degree in electrical engineering and started out wanting to do SOMETHING in fluid dynamics. SO with that said, here is how it works with heated exhaust gases, i will give you a BRIEF overview, if you want the full story pm me.

You want exhaust FLOWING, HOT gas cools.....causing it to slow in the pipe because cooler air is more dense and that makes it harder to move. In an effort to keep these gases HEATED without causing turbulence is SLOW IT DOWN. That can be acheived by a small pipe, INSULATE THE PIPE, or.......a butterfly valve(exup). A large pipe works when you are in HIGH rpm, when flow rates are up. This is where exup sucks, it slows down the gas at high rpm. The right size exhaust pipe is going to be dependant on the flow rate (volume rate, which is related to RPM and engine displacement), exhaust velocity (again related to RPM), exhaust temperature (as well changing, and as high as 2,000F)

Mark my words, look at any FULL RACE setup, there is a loss at either low end or mid range, with any motorcycle OR car. It all depends on what Throttle position/rpm you are at most of the time. If you are a racer.....full exhaust is for you. If you ride the 25mph downtown roads to show off for girls...... Stock is for you.

My .02.
I am with you on the turbulence. Turbulence is the worst thing for ANY flow. I would be interested to see based on the velocity of the gases at high RPM does if it make a huge difference. It being so close to the exit of the exhaust. I am going to say probably not but what do I know. Your summary was right on though and I am with you 110%.
 

·
Redline.......White Light
Joined
·
751 Posts
Well with our bikes, 06+ r6, being after the cat, i would have to agree, it doesn't make a HUGE difference. The catalyst in the pipe right before the box does more of a job of low end back pressure, but the Exup is open full by 7k rpm so.....not sure. The box does a good job of keeping the heat up too(ask my legs on hot days) But those items are designed to flow better at high rpm, so the exup is used to give that little extra. To completely switch gears, the exup is a lot closer to the "front" of the exhaust on all r1's.
 

·
Phi Phi K A
Joined
·
823 Posts
Nevermind
 

·
Phi Phi K A
Joined
·
823 Posts
One last time, removing the EXUP will effect the computer if you removing. You "will" have an error code message if you removed the EXUP. Anyone saying you won't doesn't know what they are talking about. Can the EXUP be removed and the computer problem resolved? Yes. But it's a headache to do so.
Paytheon, have you lost your mind?

I have been running a full exhaust(no exup valve) for as long as I have owned the bike. Correction, the first thing I did was change the slip on to an after market which still removes the valve. That lasted a week before I got the full system. I have NEVER had an error code or ANY type of ECU issue. If you remove the valve in the stock exhaust you WILL NOT have an error code or computer problems, so long as you keep the servo motor plugged in with no cables attached. No computer problems will need to be resolved. What do I need to convince you of this? Should I video tape my bike running with no valve? Does anyone else want to chime in here? Why do you think that there will be "computer" problems? What are you talking about? What are you basing your statement on? Why would you tell people something that just isn't true?
 
1 - 20 of 61 Posts
Top