F3 Why Disconnect Exhaust Valve? - MVAgusta.net
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post #1 of 23 (permalink) Old 05-22-2018, 02:47 PM Thread Starter
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F3 Why Disconnect Exhaust Valve?

So I got an ECU studio mapping kit in order to enable the blipper on my EAS 2.0.

It was suggested I use the maps with the exhaust servo disconnected settings and remove the cables from the servo.

My exhaust servo works 100% and I am using stock pipes and silencer. What benefit would disconnecting the exhaust servo have? Would I not lose bottom end drive by having the valve open at lower RPM ? I imagine no benefit at higher rpm.

Lastly, if I did remove the cables, is the valve default position open or closed?

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post #2 of 23 (permalink) Old 05-22-2018, 02:52 PM
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Default position: Open.

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post #3 of 23 (permalink) Old 05-22-2018, 05:46 PM
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Quote:
Originally Posted by silentservice703 View Post
Default position: Open.
I think this is true for the F4 but I seem to recall with the F3 and they are sprung closed. No idea why but I think they are. It's an easy test on the Dyno the F4 lost 50% of power.

The kit maps / ROMs from MV are all designed for use without the exhaust servo and they do away with the fueling compromises generated by complying with emissions regs.

So if you want to use those maps / ROMs then that would be the advice. Clearly if you are dynoing the bike then you could stay with the exhaust servo Rom and tune from there.

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post #4 of 23 (permalink) Old 05-22-2018, 06:20 PM
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The F3 is sprung open by default. If you remove the cabling it will stay in the open position. The servo goes to the closed position however when off... maybe this is what you remember? I have installed an exhaust servo eliminator and cabling removed. Its open all the time.

With most recent stock tune and in the always open position with stock exhaust I have noticed an increase in deep sounds at idle and more pronounced backfire noises when downshifting and slowing down. More torque in lower rpm but that is my butt dyno giving the feedback. No change to wide open throttle at high rpm power.

If you are doing a stock tune and adding blipper and programming the servo out you can safely have the servo and cabling removed in my opinion. If you want to keep it on thats fine as well. You can always just use the power up top with more throttle and a downshift.
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post #5 of 23 (permalink) Old 05-23-2018, 03:04 PM
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The valve is sprung open, so if anyone has an error and it is shut, either the servo is stuck at the closed position or the valve has seized. The servo is used to close the valve at lower revs.

I disconnected mine because the servo failed. I serviced the motor and it works, but in it he end it was easier to remove the servo, cables etc.

They are not he most reliable of parts on most bikes.

I’m not sure if anyone has any definitive proof that removing it has any performance effects either way though?

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post #6 of 23 (permalink) Old 05-23-2018, 04:03 PM
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I got no proof for the F3, But i've seen Brock from Brock's performance closing and opening and actually removing the servo valve wires while doing a dyno run with a suzuki gsxr1000 2017.

And the valve is open in Neutral. When you kick the bike in first gear, the valve actually closes a bit to 25% or so to lower noise.
On throttle the valve will completely be open after 5000rpm if I remember that correctly.

And he did a dyno run with everything working as intended and a dyno run with the cables disconnected (valve always open)
In the end it was like 0.1 hp more and 0.1 more torque.

So basically nothing changes, and wont be noticable. But thats on the Suzuki, and who knows what it will do with the MV.

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post #7 of 23 (permalink) Old 06-02-2018, 04:48 PM Thread Starter
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Okay, so I will be disconnecting the servo cables.
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post #8 of 23 (permalink) Old 06-02-2018, 08:41 PM
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The exhaust valves in the muffler (Honda, BMW) are noise emissions. Exhaust valves ahead of the muffler are there to improve torque curve (eliminate dips).

If you will take a moment to study some WSBK bikes and some MotoGP bikes you will discover that they also use exhaust valves controlled by the ECU for power delivery smoothing.

Brock's 0.1 hp gain doesn't show the torque curve changes.

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post #9 of 23 (permalink) Old 06-03-2018, 11:53 AM
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Perhaps a silly question and sorry if this was covered elsewhere but is there any risk to the engine when running valve fully open or while riding to dealership with the fault on? If not I'll just yank the cables since I've currently got the malfunction happening....
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post #10 of 23 (permalink) Old 06-03-2018, 08:29 PM
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Quote:
Originally Posted by MrTrogg View Post
Perhaps a silly question and sorry if this was covered elsewhere but is there any risk to the engine when running valve fully open or while riding to dealership with the fault on? If not I'll just yank the cables since I've currently got the malfunction happening....
In a word....No .

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