exup servo

colin

colin

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hi,new to fz1 new to forum.with out going into to much detail the removal of the exup cables when fitting aftermarket slip on does what? i am reading of mods to do with removing the servo,how does that help? oxygen sensor eliminater removal again what gains do you get from these mods.a lot of questions for my first post but a lot to learn regards to all from the uk.
 
colin said:
hi,new to fz1 new to forum.with out going into to much detail the removal of the exup cables when fitting aftermarket slip on does what? i am reading of mods to do with removing the servo,how does that help? oxygen sensor eliminater removal again what gains do you get from these mods.a lot of questions for my first post but a lot to learn regards to all from the uk.
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In regards to the gen 2 FZ1 the exup system is basically just there to reduce the noise level of the exhaust at idle and low rpms. Aftermarket exhausts can't use the exup, so you simply remove the cables and leave the servo attached under the seat to avoid a check engine light (or you can get an eletronic gadget from Graves that replaces the exup to avoid the light). Generally the o2 sensor is removed as part of an aftermarket fuel management system such as the power commander as it is not needed in this case.
 
So for the Gen 2, removal of the Exup valve and the fitting of another slip on is straight forward and doesn't ruin performance ?
 
Mono said:
So for the Gen 2, removal of the Exup valve and the fitting of another slip on is straight forward and doesn't ruin performance ?
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That is correct. Just remove the EXUP cables, but leave the servo motor connected to the harness and you're good to go. More power and less weight. What is not to like!
 
colin said:
hi,new to fz1 new to forum.with out going into to much detail the removal of the exup cables when fitting aftermarket slip on does what? i am reading of mods to do with removing the servo,how does that help? oxygen sensor eliminater removal again what gains do you get from these mods.a lot of questions for my first post but a lot to learn regards to all from the uk.
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OPPOSING OPINION (to the majority view) : I've spoken with several Yamaha service technicians, Yamaha corporation and a very knowledge ex-racer and current Triumph dealer. They all say the EXUP valve does what Yamaha says it does, which is:

Yamaha's patented Exhaust Ultimate Power Valve (EXUP) monitors engine rpm and adjusts exhaust flow for maximum performance at all rpms with no flat spots. This system also optimizes fuel economy and reduces emissions.
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Similar systems are used in by Honda, Suzuki, Triumph, Kawasaki, and Ducati that I know of, and I imagine, most makes use a similar device. Honda's went by the names Honda Titanium Exhaust Valve (HTEV) and Honda Variable Intake/Exhaust (H-VIX), appearing on the CBR600RR and Honda CBR929RR. Suzuki's version is called Suzuki Exhaust Tuning (SET). Triumph Daytona 675 triple uses an Exhaust Valve Actuator.
 
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Polestar said:
OPPOSING OPINION (to the majority view) : I've spoken with several Yamaha service technicians, Yamaha corporation and a very knowledge ex-racer and current Triumph dealer. They all say the EXUP valve does what Yamaha says it does, which is:......
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My bet is that is the official answer but the real answer is to hide the popping sound that the AIR system is making. Whenever you remove the stock exhaust/cat/valve the popping is real apparent. This popping would have never made it thru the EPA sound rules.

I recently did some exhaust testing that lead my to a combination of exhaust system that almost totally covered the power dip. The factory could have used the valve to do the same thing if they had elected to really chase a smooth power band.

AW
 
Polestar said:
OPPOSING OPINION (to the majority view) : I've spoken with several Yamaha service technicians, Yamaha corporation and a very knowledge ex-racer and current Triumph dealer. They all say the EXUP valve does what Yamaha says it does, which is:

The Exhaust Ultimate Power Valve (EXUP) is a device fitted to some Yamaha 4 stroke engines that constantly adjusts the internal diameter of the exhaust system to better suit engine speed. At low engine speeds the wave pressure within the pipe network is low. A full oscillation of the Helmholtz resonance occurs before the exhaust valve is closed, and to increase low-speed torque, large-amplitude exhaust pressure waves are artificially induced. This is achieved by partial closing of an internal butterfly valve or EXUP valve, within the exhaust creating an artificial atmosphere. The alteration of the pressure controls the behavior of reflected waves producing an area of discontinuity. Closing the valve increases the local pressure, inducing the formation of larger-amplitude negative reflected expansion waves. A servo motor controlled by the ECU opens and shuts the valve. The valve goes from being almost fully closed at idle speed, through to fully open at higher engine speeds. This ensures superior low to mid-range performance, more linear power output and reduced exhaust noise levels while the valve is in its reduced opening position."
....
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Well not to further escalate this, but your quote above is not exactly true when it comes to the EXUP that's on the Gen II FZ1. I think it's more applicable to Yamaha's older EXUP valve that was in the collector of the header and varied the volume of exhaust flow (Gen I FZ1 for instance). If you look at the EXUP valve on a Gen II bike you will quickly realize that at idle it's completely open so not sure the above quote is completely applicable.
 
NJFZ1 said:
Well not to further escalate this, but your quote above is not exactly true when it comes to the EXUP that's on the Gen II FZ1. I think it's more applicable to Yamaha's older EXUP valve that was in the collector of the header and varied the volume of exhaust flow (Gen I FZ1 for instance). If you look at the EXUP valve on a Gen II bike you will quickly realize that at idle it's completely open so not sure the above quote is completely applicable.
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You may be right. Perhaps I posted an inaccurate quote (I've changed it).

However, my real point is many knowledge folks I've spoken with disagree the current EXUP is just a flapper valve to lower decibels for sound compliance. Add to that the wide spread use of EXUP inspired technology on most other performance bikes and it causes me to wonder.

I really don't have an axe to grind here- and I'm not a tech head. In a sence, I'd like to believe the EXUP was just sales "sizzle" with no performance enhancement, because I'd like to go with an MIVV SUONO; but I'm just not convinced.

Cheers.
 
Polestar said:
...
I really don't have an axe to grind here- and I'm not a tech head. In a sence, I'd like to believe the EXUP was just sales "sizzle" with no performance enhancement, because I'd like to go with an MIVV SUONO; but I'm just not convinced.
...
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Well many of us have replaced the stock muffler with a variety of slip-ons. This has resulted in increased power w/o any ill effects from the removal of the EXUP valve. I say just go for it :D
 
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