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I know the valve can screw up and not function properly, but what does it do when it IS functioning properly? I know my S1000 had a valve similar to this that was designed to increase low end torque. Is that what it does on the 675?
 

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Benefits to pinning the valve open or removing the "ExUp valve", and mapping for the changes, range from slight increases in output to nothing. This depends on other modifications that may or may not benefit. Without remapping for the altered flow, and especially the altered pulse tuning, output can actually decrease.

The only detriment is an increase in noise output up through 6000 rpm.

Despite the marketing-speak that many companies have used to sell this emissions noise reduction device to the public as a "performance benefit", it has been proven otherwise too many times to count. The "ExUp valve" has been around in several forms since the late 1960's. The patent belongs to an ex-Ford engineer and was developed for the Boss 429 "Shotgun" engine program as a noise reduction device. He now works in the automotive and marine aftermarket industry in California. He is a very sharp individual, and interesting to talk with on this subjectand others.

In modern motorcycles, the valve is operated by the ECU up through 6000 rpm, where noise emissions are tested. After this point the valve is held fully open in most engines.

On the 675 engines, in stock form, or with bolt-on modifications, most engines we have tested show little to no benefits to keeping the valve open and remapping, and slight gains on a couple when the shaft and throttle plate were removed and mapped. Removing the collector and ExUp casting and replacing it with a better collector design does show noticeable improvements after mapping.

I hope this helps.
 

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BOTM Marshall
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Wrong! But not worth debating.

sassafras
The folks who designed the bike have to say.....

http://www.r1-forum.com/forums/archive/index.php/t-262749.html

Originally Posted by Simon Warburton, Triumph product manager for the Daytona 675
while Triumph's Daytona 675 nestles one in the secondary pipe, between the collector and the end-can, just after the catalytic converter. 'We didn't want the weight and bulk of the valve and its actuator at the back of the bike,' says Triumph's product manager, Simon Warbuton. 'This location is the best place for keeping the bike compact, putting mass where it will have the least impact on handling while still giving us the effect we wanted.'And the desired effect has changed. With advanced injection and ignition systems, the role of the throttle valve is no longer about filling the midrange or chasing horsepower. 'On the 675 it has nothing to do with emissions or peak power.' continues Simon. 'There's a small effect on torque at lower engine speeds and it can improve driveability in some conditions, but it really helps on noise - a valve in the secondary pipe helps to take the edge off exhaust noise without compromising power.'
Had to dig this out of a locked EXUP thread. Originally posted by [FLUX]
Triumph675.Net Forums - View Single Post - 675 EXUP Testing
 

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The folks who designed the bike have to say.....

http://www.r1-forum.com/forums/archive/index.php/t-262749.html

Had to dig this out of a locked EXUP thread. Originally posted by [FLUX]
Triumph675.Net Forums - View Single Post - 675 EXUP Testing
So you basically quoted a guy who says that it "[has] a small effect on torque at lower engine speeds and it can improve driveability in some conditions" as counter to my argument that it isn't entirely worthless? Ok. Cool, thanks.

It's worthless when properly tuned out, but Triumph tunes the ECU mapping to expect it to be there (especially at low throttle opening) and just removing it does alter the way the bike runs at RPMs where it would normally be partially closed. There is no debate that taking it off and then tuning for the changes effectively negate it's benefit, but the key here is 'remapping'.

EDIT: Just to further my point a little... Here is the original quote from JD at Hordpower about how he produced the identical dyno curves with and without the EXUP:

I agree, if you run a stock tune or TOR tune and disable or remove the valve, you will likely lose a bit of low/midrange, simply because the mapping is off. However if you remap for the missing valve, then the result is the same power. The valve makes no difference to power, but the tune does.
...

Thanks Power-Tripp for the information. It's quite interesting that there is so much variability and misunderstanding about what the ExUp valve accomplishes. Honestly I'd never expect it to actually _add_ power, but I can't imagine an engine that is tuned for the increased backpressure doesn't need some modification when that impediment is removed. Much like how a slip-on often lowers torque until the correct re-mapping is completed.

sassafras
 

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well ive taken my EXUP valve off twice, and withen 30 minutes of test riding took it right back home and put it back on both times (and both these tests were months apart). the low end is definitely weaker in my case. from idle to about 6k the triples torquey engine feels a little more like a jap inline 4, (not what I bought this bike for). The sound is much better at the lower RPMs though thats for sure.

now this is without getting a proper tune to make up for the loss of power. Plenty of people on here have taken it off, gotten themselves a tune, and have gained back the power, and in some cases exceeded it. So it depends on what you are looking for. In my case, I tried a few different custom tunes from this site and nothing gave me the full power back. I am a broke college kid otherwise I would have it off and to the dyno asap, because the sound is sexy.

Some people are claiming they have NO loss of power without it and without a tune, I have no reason not to believe them. but in my case, and a co-worker who also has the daytona 675, both noticed a more than acceptable loss of low end to justify it. So it is your call.

on another note, my valve siezed up on me for the first time the other day. and I followed the thread on freeing it up, and with the valve properly lubed, I noticed an increase in low end power (probably from the valve being so much easier to open/close on slight throttle responses). so for those people who havent had any engine lights come on, it might still be a good idea to lube it every once in a while.
 

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Like Hord we tune lots of 675s and we have noticed very little differnce between having the valve and not having the valve. Except to noise levels that is. We are firm believers that the valve and cat is a 1kg (2.2lbs) waste of space. Any rider who says they can feel a difference with the vale in or out has one sensative dyno ass!

We remove the pair just to get rid of later problems in life for the owners.

Now all that said and comments made about the mid range let me throw this into the pot. The ST doesn't have the EXUP valve and is stronger in the mid range. Reasons being, the header pipes on the ST are 10mm shorter and the cams are milder all to give more mid range torque. The ST doesnt have the airbox intake at the front adding to noise so no EXUP or flapper valve needed. Also the Aprilia RSV4 WSB bike is raced with an EXUP valve.
Let the debate continue.
 

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Like Hord we tune lots of 675s and we have noticed very little differnce between having the valve and not having the valve. Except to noise levels that is. We are firm believers that the valve and cat is a 1kg (2.2lbs) waste of space. Any rider who says they can feel a difference with the vale in or out has one sensative dyno ass!

We remove the pair just to get rid of later problems in life for the owners.

Now all that said and comments made about the mid range let me throw this into the pot. The ST doesn't have the EXUP valve and is stronger in the mid range. Reasons being, the header pipes on the ST are 10mm shorter and the cams are milder all to give more mid range torque. The ST doesnt have the airbox intake at the front adding to noise so no EXUP or flapper valve needed. Also the Aprilia RSV4 WSB bike is raced with an EXUP valve.
Let the debate continue.
When removing and tuning bikes without the EXUP, is there a pretty standard modification you make to correct for this or is it really relative to that individual machine?

sassafras
 

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I had removed all the EXUP valves on all my bikes that come with it and this too will be done without it. Even it does make no differance in power whatsoever, the extra noise is always music to my ears. Just read this up to make myself happy.
 
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