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Git er' done
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Discussion Starter · #1 ·
I imagine by now everyone and his brother has seen some of the dyno charts for the new R1, but has everyone noticed the slump around 7000k rpm? OK, I wonder whats causing it, could it be the catalytic converter tucked in the pipe? A new way the EXUP activates? A flapper type valve in the intake (ram-air) to control noises in the intake?(epa happy) ( I know the Honda RC51's were made this way, which was easy to remedy to gain back its punch). Or is it a leanish condition caused by (epa mandated) mapping? Any ideas? I know that spot in the powerband is NOT permanent! If that area alone were erased it would help out the midrange and roll-on performance of the bike. Any ideas?
 

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its the cat!!! your full system will take care of that-it's been said before
:bs The cat would not generate such distinct slumps, specially not if placed behind the exup.
I have three guesses:
- sub-optimum map (emission regulations) or
- exup not adjusted perfectly or
- control of that second flap in intake not yet perfect

I'd rather rule out the last one because aftermarket exhausts seem to help, but so do slip-ons that go after the cat.
As exhaust manufacturers most likely remap the motor to get a nice courve I'd guess it's the mapping.
That's why I'd like to see a stock R1 before and after a custom map!
 

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Juerg said:
:bs The cat would not generate such distinct slumps, specially not if placed behind the exup.
I have three guesses:
- sub-optimum map (emission regulations) or
- exup not adjusted perfectly or
- control of that second flap in intake not yet perfect

I'd rather rule out the last one because aftermarket exhausts seem to help, but so do slip-ons that go after the cat.
As exhaust manufacturers most likely remap the motor to get a nice courve I'd guess it's the mapping.
That's why I'd like to see a stock R1 before and after a custom map!

The concept I’ve been told makes sense to me. The exhaust pipes are to long from the point of exit. It’s been proven that inline fours running underseat exhaust seem to all have some sort of midrange dip from all the bends in the exhaust pipe. The longer the exhaust has to travel to completely expel from the engine the more horsepower it loses. Though you can’t have the pipe to short because there is a certain level of back pressure that is needed in order to run correctly. Basically to much pipe, and not enough pipe are horsepower killers.

The under seat works well for the twins simply because the pipes only have to travel a foot before they actually hit the can. Where the inline fours travel through the header’s n the front of the bike, relocate under the engine, up until its behind the engine and continues to climb until its under the seat than rear tail pipe. We have already seen aftermarket dynos of slip-ons which removal the cat all together and it still is plagued with the midrange dip.

Will it be that big of a deal? Unless you race the bike and push it to its limits consistently most likely not.
 

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your mom looks hot
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it's not worth talking about because the bike will ride and behave differently once you remap with a PC3 and add a slip-on or full exhaust. the PC3 will change the torque curve dramatically.

the other thing to think about is that if you're really riding in a fashion where you need that extra performance (track) then you'll never drop below 9000rpm anyway. obvoiusly you're going to keep it in the rev range where it makes power.

fact is, even if there is a dip after you remap, you're not exactly hurting for power or torque no matter how you cut it. i doubt the flat spot is going to hurt your trackability unless you're gary mccoy or loris capirossi and you use the back end to steer when it's lit up and smoking.

ok, lastly, have you ever noticed how fast a bike spins through a 500rpm flat spot? it's less than a second before you're in the power.

:thumbup
 

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Beeeeeer!
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Your all wrong. It's the new headlight design used on the '04. The light waves emitted from the new design are interfearing with the pressure waves in the exhaust. It just happens to be effecting the 7000 RPM range. The only fix for this is to remove the head lights or cover them up. :crash
 

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Moving Chicane
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CDRacingZX6R said:
The concept I’ve been told makes sense to me. The exhaust pipes are to long from the point of exit. It’s been proven that inline fours running underseat exhaust seem to all have some sort of midrange dip from all the bends in the exhaust pipe. The longer the exhaust has to travel to completely expel from the engine the more horsepower it loses. Though you can’t have the pipe to short because there is a certain level of back pressure that is needed in order to run correctly. Basically to much pipe, and not enough pipe are horsepower killers.

The under seat works well for the twins simply because the pipes only have to travel a foot before they actually hit the can. Where the inline fours travel through the header’s n the front of the bike, relocate under the engine, up until its behind the engine and continues to climb until its under the seat than rear tail pipe. We have already seen aftermarket dynos of slip-ons which removal the cat all together and it still is plagued with the midrange dip.

Will it be that big of a deal? Unless you race the bike and push it to its limits consistently most likely not.
Well, couple things to think about. Twins do not necessarily have shorter runners. Remember that the front cylinder is pretty far forward and they maintain equal length for balance, so there is spachetti work under the sump to add lenght to the rear cylinder's run.

But since we are talking fours, one thing kind of disproves the theory of 4s and underseats....the Honda 1000RR power curve has not drastic holes in it.

I dont know that the slip-on references are necessarily accurate as they do not always indicate that they are de-catted, so there is assumption. The TBR graph is a good example as it fills it in pretty nicely.

Also, the full system graph like the Tiforce is not with remapping, so it dumpes the cat and Exup, but we have not seen this problem from any other Yam with Exup. But that seems to rule out a map related problem.

In time more pipe info will be available to help tell who de-cats and who doesn't so we can be sure of the effect, but its seems for the majority of the info I have seen, it points to the cat.
 

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we meat again
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GXRKLR said:
Your all wrong. It's the new headlight design used on the '04. The light waves emitted from the new design are interfearing with the pressure waves in the exhaust. It just happens to be effecting the 7000 RPM range. The only fix for this is to remove the head lights or cover them up. :crash
:lol :bash

I thought it was the new diamond tail light that prevent the exhaust gas coming out properly... :crash
 

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we meat again
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repoman said:
A couple of well placed stickers can cure any performance problem.

Repo
repoman = Typical Riceboy

:lol
 
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its because of the tuning,...its tuned for high horsepower, and the exup helps build power below 7000, so when the exup is open and the exhaust turns into a free flowing exhaust then you get one curve, and when its closed you get another curve. now if you put the two together the "seam" of the two have to connect, and at that connection, the exup happens to make more power then wide open, so for a split second it dips down

you could correct this by opening the exup later (down side would be that you would then have the exup making less power then the free flowing exhaust, and you would get a huge bump)

im sure they did this because the combination in yamaha's eyes is better this way.
 
G

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blus is exup closed......better torque
red exup open......higher HP
combination.......best of both worlds IYO(in yamahas opinion)


so you could adjust the activation point anhd try to match the curves at the same HP

IE at 7000 exup closed makes 100hp and open makes 95 hp, then it would be advisable too open the exup at 7100 or so when they are both making 98 hp or so
 

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I second the theory of kc1717. This would just mean that the exup mapping is far from perfect then. So we need a PC for the exup! ;)
However it still could also be related to fuel mapping, one thing that could easily ruled out if somebody did a custom map on a stock R1.
Anybody to help out here?

I'd completely rule out the cat however, comparisons with full systems (Akra, other thread) did show very little differences at max HP, what means that the cat isn't a bottle neck at max. gas flow.
I don't see how it might be responsible for midrange losses in a very limited rpm range if located behind the exup!
 

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Git er' done
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Discussion Starter · #17 ·
Back to a flepper type valve scenerio, I know for a fact that on my RC51 the ram air intake tract had a flapper type valve in it to drown out intake noises at a certain rpm for epa reasons. Once the system was disabled it made the bikes power curve much smoother and beefier in the lower midrange area. I could easily tell a difference in the way it sounded afterword (more throatier) and quicker to rev through that particular area in the rev range. Im just curious if the 04 R1 might have a similar restrictive setup in its intake tract because of epa regs. That would most certainly cause a stumble (flatspot) in its powerband also. A full system, slip-on system or pc3 would probably help push proper gas and air but wouldnt be able to correct a restrictive flapper valve scenerio no matter what! It would need to be removed or disabled just my .02 worth.
 

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what! It would need to be removed or disabled just my
... or adjusted, what again means some electronic gizmo...
I'll have to study the inlet and outlet side a bit to be able to point at the source of the problem.
For example I am not sure if the valve actually does something else than just stay open on a full-throttle dyno run. This would rather rule it out as the source for that slump. The exup on the other hand is sure to work through the rev-band...
We may also be looking just at a resonance problem in the exhaust or intake.
This problem may be hunted down only by systematic search and changing only one component a time.
My personal hit list:
1. Exup
2. Mapping
3. Inlet valve control
It will be interesting to see how European R1 perform, if they are different form U.S. bikes. I bet that the euro-exhaust will be different from the U.S. for example.
Also, due to different regulations, the injection may be tuned differnently.
Just let's keep in mind that, if it was easy, Yamaha would have avoided that slump.
 

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Git er' done
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Discussion Starter · #19 ·
due to different regulations, the injection may be tuned differnently.
Just let's keep in mind that, if it was easy, Yamaha would have avoided that slump.


True, it may just come down to the mapping. Epa mandates a certain emmission so Yamaha had to comply, thus a lean area in the power curve.
 

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...where we are talking potentially both about noise (pointing to valve drive) or pollution (map)...
Time will tell, as soon as somebody does a custom map on a stock bike...
 
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