Interesting, so it would appear that removing it can't hurt but, more to the point, leaving it on makes no difference either, apart from a bit of weight.

 

Yes, that's a way to see it
I didn't mean for every one to throw the EXUP away but you have a good point.

The logic tells me Yamaha (and other manufacturers) wouldn't do such thing if it didn't have any function at all.

Since i don't have any dyno results to back up with perhaps i shouldn't said anything about if it really is totally useless or not, that wasn't really my point, the main thing was the surprisingly small range it works in, both rpm and opening level.

 

This caught my attention a while back. I was going through some old tuning books and came across this:

Exhaust pulses will only be able to work if they are allowed to travel freely along the exhaust system. They can be dissipated by putting steps, sudden section changes or chambers into the exhaust. The same pulses make noise and they can be reduced significantly by the same mechanisms employed in a silencer. Yamaha did this when they put their EXUP valves into the exhaust systems of the FZR 1000 and the OWO1.

Either a guillotine or butterfly valve was used to block off part of the secondary pipe, just downstream from the 4-1 collector. It was operated by a servo motor and an engine speed sensor, so that the valve was withdrawn above a certain speed (about 6000 rpm) and projected into the exhaust below this speed.

The exhaust was tuned like a race system, to give beneficial effects between 9,000 and 11,000rpm and this would normally create bad effects at 6,000 to 7,000rpm when the pulses got out of phase. Instead, the EXUP valve acted like a baffle and prevented the pulses from being reflected back along the header pipes. The result was that the engine behaved as if it had a neutral exhaust through the midrange and a race exhaust at high speeds.

Bibliography- Motorcycle Tuning by John Robinson (published 1986,1994)


When I replaced my standard (Euro '07) exhaust with an Akrapovic full system, power dipped from 1,200rpm to about 3,500rpm. It wasn't a huge power drop but it was felt none the less.
My fix came about by changing (lowering) the gearing....kinda hiding the power dip.

 

This caught my attention a while back. I was going through some old tuning books and came across this:

Exhaust pulses will only be able to work if they are allowed to travel freely along the exhaust system. They can be dissipated by putting steps, sudden section changes or chambers. The same pulses make noise and they can be reduced significantly by the same mechanisms employed in a silencer. Yamaha did this when they put their EXUP valves into the exhaust systems of the FZR 1000 and the OWO1.

Either a guillotine or butterfly valve was used to block off part of the secondary pipe, just downstream from the 4-1 collector. It was operated by a servo motor and an engine speed sensor, so that the valve was withdrawn above a certain speed (about 6000 rpm) and projected into the exhaust below this speed.

The exhaust was tuned like a race system, to give beneficial effects between 9,000 and 11,000rpm and this would normally create bad effects at 6,000 to 7,000rpm when the pulses got out of phase. Instead, the EXUP valve acted like a baffle and prevented the pulses from being reflected back along the header pipes. The result was that the engine behaved as if it had a neutral exhaust through the midrange and a race exhaust at high speeds.

Bibliography- Motorcycle tuning by John Robinson (published 1986,1994)

Good input Liam. I think the actual restriction in degrees measured doesn't say everything cause there will be turbulens around the butterflies that make a larger obstacle than just the blocking surface.

What puzzles me is the low rpm range it work in, at 3250rpm the valve is alredy fully open, i would sure have guessed it would operate up to 6-7000rpm which at least is half way up the rpm range?

A interesting point, from what you wrote, is if the EXUP doesn't really work as a restricton on the exhaust gases coming from the engine but to the reflecting pulses from the exhaust piping.

Since my exhaust system is "freed up" the back pulses are different than on a stock bike, which could explaine why i don't notice any significant difference with or without the valve in place?

 

I must admit I expected it to work longer through the rev range too but as mine is street only I intend to leave it in at the moment. Yamaha put it there for a reason and they certainly know more than I do, I can see a race setup scrapping it as they are virtually never in the low rev range.

 

I personally think, in the good old days of tuning a bike, there where only 2 choices... good bottom and strong midrange or a good mid and strong upper top end, thus sacrificing the bottom end power.

Over the years designers were able to overcome design flaws to give the best of both worlds...good bottom, strong midrange and great top end power.
As a result the Exup is now resigned to work in such a low operating range.

Please feel free to laugh at my thoughts...I know some of them are way out there lol, but hell, I'm still learning.

 

you should check it under load .
the ecu reads tps ,rpm and speed to calculate load.
you can put a camera in there and take a short ride .
might be interesting .

 

I will do that, i've already made a scale so i can monitor this while driving but i thought a degree scale would be nicer to look at, not that practical while driving dough

But you'r right, i overlooked the influece of engine load, thank's for the tip.

 

Good reading.

 

It's been raining cats and dogs the entire day but, in the quest of the mighty EXUP i went out for a short test anyway :sneaky

Of cours it couldn't be any full scale test but so far i couldn't find anything contradicting to what i've seen earlier.
And to morrow the street YEC is going in so then i can't test this any more.

I think the bikes sold for the european market (and some more) are concidered the least restricted R1s, arn't they?
Would be interesting to se how a US or even better a Californian bikes EXUP behave.

 

I work for a shop that also sells Ducati & BMW motorcycles. These brands have very similar exhaust valves. More interesting, Biaggi's Aprillia superbike has one while Spies' old R1 superbike didn't.

I've been listening to the theory of the EXUP valve since they were first released. They have consistently claimed that it broadens the power band but they are a little light on details.

I think that the EXUP could be very helpful dealing with backfiring when copping the throttle. Not very sexy but true nonetheless.

At lower engine speeds, the sonic pulses are "out of phase." That is to say that the positive pressure pulse doesn't arrive at the exhaust valve in a way that is advantageous. In fact, it can have timing that hurts performance. By closing the valve, the exhaust pressure/velocity is higher thus diminishing the negative effect. (The higher the velocity, the more kinetic energy and flow reversal is less likely.) There will also be a change to the sonic response by changing the effective length and changing it from an open "pipe organ" to more of a closed "resonance chamber" form.

Note that Biaggi's Aprillia has demonstrated outstanding peak power since it was introduced but has been weak in the mid-range. The exhaust valve may be their way of improving it.

I haven't measured the flow but I imagine the butterfly will restrict exhaust flow at the higher engine speeds.

How effective is it? I don't know.

 

Originally Posted by adamsys>

At lower engine speeds, the sonic pulses are "out of phase." That is to say that the positive pressure pulse doesn't arrive at the exhaust valve in a way that is advantageous. In fact, it can have timing that hurts performance. By closing the valve, the exhaust pressure/velocity is higher thus diminishing the negative effect. (The higher the velocity, the more kinetic energy and flow reversal is less likely.) There will also be a change to the sonic response by changing the effective length and changing it from an open "pipe organ" to more of a closed "resonance chamber" form.

Note that Biaggi's Aprillia has demonstrated outstanding peak power since it was introduced but has been weak in the mid-range. The exhaust valve may be their way of improving it.





I get what you're saying. Would I be correct in thinking that the EXUP valve could aid cylinder scavenging at lower rpm?

 

the purpose of exup is to slow down exhaust gase flow at low rpm .

during the exhaust stroke , the piston is pushing the exhaust gases to the exhaust pipe .
at low rpm , its easy for the piston to push all the exhaust gases to the pipe .so if there are no obsticles , the pressure in the pipe will be atmospheric on the next exhaust stroke .
the exup is slowing down the gas flow to a speed that will generate low pressure at the next exhaust stroke .its called back pressure .
the timing is critical in order for this to happen.
this helps the engine to get rid of the exhaust gases easier (due to back pressure , piston is working less) and more important , to help push some fresh mixture during the end of the exhaust stroke (valve overlap) .the low pressure in the pipe is "sucking" fresh mixture into the cylinder.

as rpm get higher the exhaust gas speed is not fast ,compared to engine speed , so there is always high pressure in the pipe . so at high rpm , the best pipe is wide open .its not possible to generate low pressure in the pipe at high rpm , because the gas flow is too slow compared to piston speed . thats why the exup is fully open at speeds higher then approx 5k rpm .

 

So with all that in mind, would you say for street riding they are best left on ?

 

yamaha article.

The variable EXUP valve assembly fits in the muffler area and works off a computerized sensor adjusting exhaust pressures based on a reading of engine revs, throttle opening and more. While the actual EXUP valve in the exhaust responds to the sensor commands, other information is relayed to the ignition system to optimize timing.

 

Ok guys, as I've said earlier in the thread..."some ideas I have are way out there".

So now that that's out of the way....Adamsys and Ozzian you've got me thinking!
Why should the EXUP servo be the only thing to control the EXUP?

Adamsys mentioned 2 strokes. In 1985, Rotax produced new 250 GP engines with a simplified type of Yamaha valve. A guy named Hans Holzleitner developed a guillotine slide pneumatic valve. The valve would rise and fall in the top of the exhaust port. This increased exhaust duration at high rpm and decreased at speeds below 11,000rpm. The valve was both spring loaded and controlled by exhaust pressure.

At lower engine speed and load, exhaust pressure is reduced so that the guillotine slide drops to the fully lowered position, while at the same time being pushed down by spring pre-load. As engine speed and load increase so does exhaust pressure, the exhaust pressure in turn rises the valve in response to match the pressure rise.

Now as I see it, Yamaha have already given us the valve (EXUP) itself, so all that would have to be done would be to spring load the EXUP.

 

Hmm, now your going
I've ones thought of a similar system but for turbo charged cars, a device that bypass exhaust gas to a secondary muffler or just a pipe straight out.
It could be controled either by exhaust pressure or by boost pressure.

If you use exhaust pressure, just like you explained, it would be a "self adjusting exhaust blockage", all it takes is a small pneumatic actuator working against a spring, taking the pilot air from the exhaust pipe, up streams the EXUP valve.
Maybe also connect the rod side of the actuator to the down stream side of EXUP to ad some stability to the circuit :thumbup

When i got my first R1, a ym-99, i thought the exup motor was identical to the YPVS motor on the RD350 i had 13 years earlier, as far as i know no one thought of the YPVS valve as a useless gimmick?

 

if yamaha wanted , they could make the exup fast enough , faster then your wrist .
any fly by wire throttle system is moving throttle by electric motor , and it is doing so very fast and high prescision.

the exup is useless above 4-5krpm , as the gas speed is too slow vs engine speed (if single collector used) .
to solve midrange there are different systems like pipe lenghts/shapes , collectors , exhaust systems (4-1 or 4-2-1 , or 4-2-2)
the exup is also becoming useless if you change valve timing .

i think bmw s1000rr is using 2 "exup" valves in cross pipes between cylinders .
if our bikes had variable valve timing , the exup wouldnt be needed .

 

Agreed, Yamaha could make the valve move faster and you're spot on about the lengths etc. I'm just playing with the Idea that:

The valve seems to work at such a low rpm and the probable benifits (if any)of fitting one to an Akrapovic full system.

 

Very interesting read gents
am simple.... i just took it off and tuned it.
installed 520 chain -1 +2 and called it a day. shes smoooph
i do get slight back fire on decel but not too bad

 

Yea, that's kinda what I did too but I don't get any backfiring.

 

Ozzian, will you be retaining your stock "freed up" exhaust after the ecu install?

The "Self Adjusting EXUP/Constant Velocity Valve" could be arranged something like the oil pump pulley return spring found on the YPVS.
Thinking about it, the tension within the spring would in all probability, be the key to operate/tune the valve for different rpm ranges. Obviously if the spring was too stiff, it would cause the valve to become restrictive. The other extreme could be, a spring with too little tension could cause the EXUP to flutter. Then again, perhaps flutter could have a benifits too. Again "a way out there idea"...valve flutter could indicate that the valve sensitivity responds perfectly to the exhaust pressure and pulses.

 

Yes i'll keep it, i'm very happy with the stock look and it seem to work fairly good, the weight of the "stock" exhaust on the other hand i would gladly loose, maybe i take a look on this in the future

I guess, since our bikes start to get som years on them, pricey aftermarket exhausts will turn up soon, i'll se what i run in to, hehe.

About just using a spring on the EXUP, it wont work as it is now.
Since the shaft is centered on the butterflies the force from the flowing exh..gases will be applied equaly on both sides and it won't open.

A gas controlled actuator would be more precise imo.
Maybe cutting of 2/3 on one side of the EXUP flap could do the job, it depend on how much friction the bearings have.

There's a spring and axial bearing working on the pulley, removing or modifying it that will take a lot of friction away.

 

full graves exhaust
smog block offs
BMC race filter
sprockets -1 front +2 rear
PCIII with custom map by mach 1
no exup or carbon canister
that is it

 

So we are kinda in the same ball park!
As you've gotten rid of the EXUP, do you feel a slight stall on initial pick-up?

Yes i'll keep it, i'm very happy with the stock look and it seem to work fairly good, the weight of the "stock" exhaust on the other hand i would gladly loose, maybe i take a look on this in the future

I guess, since our bikes start to get som years on them, pricey aftermarket exhausts will turn up soon, i'll se what i run in to, hehe.

About just using a spring on the EXUP, it wont work as it is now.
Since the shaft is centered on the butterflies the force from the flowing exh..gases will be applied equaly on both sides and it won't open.

A gas controlled actuator would be more precise imo.
Maybe cutting of 2/3 on one side of the EXUP flap could do the job, it depend on how much friction the bearings have.

There's a spring and axial bearing working on the pulley, removing or modifying it that will take a lot of friction away.

Ahh, I didn't think about the gasses pushing equally on both sides of the valve! Your diagram explains perfectly. If you don't mind, could you explain what you mean by a gas controlled actuator?

 

NO not yet
bet that makes it quick out the hole

 

Hell yea!! I eventually went back to stock gearing and worked back down, just to make sure the 15/47 was best..and yes it was, so I'm back to 15/47. Top speed is down to 275kh but the pull....ahhhh. You know what I'm saying cos you're 16/47. :boobies

 

That is still fast enough. I might just have to pick one up to try

 

I'd be curious about what you thought of it!
By the way, are we talking about your 04 or 07?

I think, if the EXUP could be made work the way Ozzian describes and with what Adamsys mentioned about the supercharging affects down low...well It could be a project for sure.

 

am about due for tires. when i install my tires i will drop the 15 in front and post up my thoughts. am sure i will like it.
do you have trouble keeping the front end down?

its my 07
the 04 does not see the street. shes track dedicated. and that biatch would buck me off with a 15 in front.



that would be a project. and an interesting one at that

 

No, the front wheel stays planted and well behaved. So what kind of torque are you putting at the wheel?

 

While researching I came across this thread titled "Throttle/EXUP opening myths".
The thread was posted by: bass16v on 06.06.2009. His findings in my opinion are very much related to the subject matter on this thread. There is also a cool youtube link showing his bike on a dyno. He also shows the Variable Intakes opening in realtime.
www.r1-forum.com/forums/showthread.php?t=264985&highlight=throttle+servo+m...

 

While researching I came across this thread titled "Throttle/EXUP opening myths".
The thread was posted by: bass16v on 06.06.2009. His findings in my opinion are very much related to the subject matter on this thread. There is also a cool youtube link showing his bike on a dyno. He also shows the Variable Intakes opening in realtime.
www.r1-forum.com/forums/showthread.php?t=264985&highlight=throttle+servo+m...

Thanks for linking to that thread, however, i don't question "bass16v"s skills, his test was very thoroughly executed, gold star for that but i'm not sure of the outcome of the test.

Could it be that the stock ECU is a little more complex and manipulation proof then we think?
Does engine dynamics really change within 600-700rpms which is how quick the ECU seem to close the throttle 20% when passed 12000rpm?

If the result of opening the throttle more by removing the "restrictions" was zero or even negative then the unrestricted street YEC would be totally pointless, i guess you'll dissagree on that, won't you Liam?

So i think i'll keep an open mind to that untill i get my own Street YEC

I've ridden my bike some more with EXUP totally removed but now during different load conditions and there's one thing i had overseen.
If i had to do lots of city cruising below 3500rpm before i got to the open roads i sure would appreciate good torque in low RPMs.

The strange thing is that i can't feel any noticable differance compared to having the EXUP in place(?) I wich i had any dyno readings to back that up, then i would know exactly what it does and why.

 

Well from what I've seen so far, mine's staying in :fact

 

You do so cause i don't think the passage through the EXUP hausing is that big of a restriction at top rpm, they probably dimensioned the total area with butterfly in place to be large enough.

So as long as you keep it working and syncroniced i can't see any drawbacks with keeping it :thumbup
Watch the cables though, on all my R1s, sooner or later they all have been shredded on the exhaust side, can't see why but they do(?)

 

With those pipes, your bike is a wolf in sheeps clothing hehehe

 

Yes it certainly is

167 SAE hp on the wheel (with EXUP) is a pretty good number from what i've seen, but maximum hp isn't all. Of course a well built aftermarket exhaust system must make some difference compared to what i have... i sure hope?

 

I agree with you and Syst, I'm more interested in the curves not the numbers.

I don't see anything suggesting the EXUP activity (below 3500rpm) on your chart. Nice curves though!!