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-   -   Exhaust Valve Operation (https://www.ducatimonster.org/forums/ducati-monster-1200/299129-exhaust-valve-operation.html)

EEEliminator 06-09-2015 01:36 PM

Exhaust Valve Operation
 
Does anyone know when the exhaust valve actually closes?

I was playing around with it and it appears to be full open at idle, I manually changed the position at idle and it got significantly quieter making me think it is full open at idle. I changed the ride modes thinking maybe it would quite it down in urban mode, but it made no difference. I'm sure it is also full open at WOT. So does it close somewhere it the middle of the rev range?

bassat5000 06-09-2015 03:03 PM

I think it's closed around 4000 rpm. But I disabled my valve by removing cable and servo, no errors are reported on the monster 1200.

Sonic Duck 06-10-2015 12:38 PM

It's closes right around the rpm sound testing is done for standards as that's its only use.

mtb 06-10-2015 03:43 PM

Ducati says it helps low-end torque. Not sure I believe it but I have never seen proof one way or the other.

hyperspd7 06-10-2015 06:45 PM

Based on these responses, anybody validate it's affect on the power band?

Brianq103 06-11-2015 09:06 AM

Quote:

Originally Posted by Sonic Duck (Post 2882841)
It's closes right around the rpm sound testing is done for standards as that's its only use.

Considering how loud the bike is stock compared to what my HD was stock I would believe they put this in as a way around the noise bylaws, especially in Europe. The most disappointing day of my life was the day the sales guy at the Harley dealer started my new Sportster up before they got the V&H exhaust in for it; I asked him if I was supposed to ride it or sew with it!:p

moshaholic2 06-11-2015 08:17 PM

Its for low end torque. Buell's pioneered it and has been copied by a few manufactures (along w/ centralized mass, engines as stressed members, underslung exhaust etc)

On a XB series Buell you can comletely feel the difference in torque between a functioning exhaust valve and one that has been wired open or changed out for a straight through "race" muffler.

*edit to add* it does quiet the exhaust on a Buell at idle as it directs the gasses through a 2nd chamber. Not sure thats the case w/ the Ducati's

EEEliminator 06-12-2015 12:47 AM

Quote:

Originally Posted by moshaholic2 (Post 2884105)
Its for low end torque. Buell's pioneered it and has been copied by a few manufactures (along w/ centralized mass, engines as stressed members, underslung exhaust etc)

On a XB series Buell you can comletely feel the difference in torque between a functioning exhaust valve and one that has been wired open or changed out for a straight through "race" muffler.

*edit to add* it does quiet the exhaust on a Buell at idle as it directs the gasses through a 2nd chamber. Not sure thats the case w/ the Ducati's

On the Monster it is definitely open at idle. It would be interesting to see before and after dyno runs although who changes just the exhaust valved without anything else... I suppose you can always disconnect the cable and do a seat of the pants feel...

Sonic Duck 06-12-2015 12:45 PM

Quote:

Originally Posted by moshaholic2 (Post 2884105)
Its for low end torque. Buell's pioneered it and has been copied by a few manufactures (along w/ centralized mass, engines as stressed members, underslung exhaust etc)

On a XB series Buell you can comletely feel the difference in torque between a functioning exhaust valve and one that has been wired open or changed out for a straight through "race" muffler.

*edit to add* it does quiet the exhaust on a Buell at idle as it directs the gasses through a 2nd chamber. Not sure thats the case w/ the Ducati's

No it is not. It's for noise regulation. Don't believe me, get a dyno, run it, undo the valve, run it again and see what you get. If anything you'll see a tiny improvement in power and smoothness with it undone.

As EEE pointed out, it's wide open at idle. How is that going to help with scavenging for low end torque? If you do investigate, I have a funny feeling you'll find it closes up pretty suddenly around 4,800 rpm which makes zero sense for any sort of performance gain.

As for Buell and pioneering....oooooooookay.

Hart 06-13-2015 10:05 AM

Hi guys,
I think that everyone that owns a recent Ducati SHOULD disable or remove the exhaust valve.
It frees up the engine on low revs.
Put the bike on the side stand and stand on it's right.
Rev it slowly and at the same time look at the side of the valve, you can watch it moving and understand how it messes up with the engine.
This feeling that the engine does not want to rev freely past idle at light throttle opening, the feeling of the sound disappearing at some revs...Its all the valve's doing! Unplug the thing go for a ride and if not convinced, plug it back in.
Actually we, monster 1200 821 and Hyper 821 owners, are very fortuned as unplugging it won't produce a warning light on the dash. We don't need a Duc.EE to eliminate the light. Maybe Ducati realized that the majority of owners are disabling it and made life easier on us...maybe!!!


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