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Discussion Starter #1
I'm putting a salvage F4 back together and after taking the exhaust off I wanted to ensure I connected the cables up to the valve properly. I ran the bike to make sure all was working well but the cables don't move at all?

I appreciate any help you can offer.

Mr. G


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The valve is normally open I believe.
It is closed down at idle and out of gear. When a gear is selected it opens slightly and then is fully open around 3000 rpm.
 

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Discussion Starter #3
I'm wondering if it is simple for noise pollution as it doesn't reroute the exhaust manifold in any way. Also when I turn the key on it fully closes but quickly opens fully right after start. Can anyone confirm this?

Thanks.


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That's the startup check. If it doesn't get the limit signals to confirm operation, it will throw a fault code. You will need to get it on to a VDS software system to check all functions and reset and recalibrate once you have finished reassembly.
 

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I've disabled mine. No need for it. Removed all cables. Valves always in open position.
 

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It is not a noise thing.....those are found in the muffler (think Honda and BMW).
Anyone who wants to argue it is not for power delivery tuning just needs to look at the Aprillia SBK bikes and most of the MotoGP bikes.
 

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Discussion Starter #10
It is not a noise thing.....those are found in the muffler (think Honda and BMW).
Anyone who wants to argue it is not for power delivery tuning just needs to look at the Aprillia SBK bikes and most of the MotoGP bikes.
Maybe, my CBR929RR exhaust valve was not in the muffler but mid pipe, near where my F4 is, and it did all kinds of motions and replied the bike for 4-1 and 4-2-1 at different times. For a street going bike with only a back pressure valve, no reconfiguring, I suspect it's for noise pollution.

I'm happy to be wrong, I would just like more than claims and please someone with a 2010-13 bike confirm the starting position. Otherwise I'll just pull the cables off the whole bit and free-ball it.


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Mate, I agree with Ed, some of it is indeed used for performance, and I also think some of it is used for noise or emission laws. I know some WSBK guys use it for various reasons, but have yet to see one on a MotoGP bike.
Either way, what seems to be the problem, how's the bike running, with or without it, the cables can really only go one of two ways only, and one of those will mess up the performance terribly. The problem is that the position of the valve is determined by rpm and speed, so sitting next to the bike looking at it will not help.
 

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Discussion Starter #12
D,

Understand all.

The bike isn't rideable, nor is the weather compliant this time of year here.

Turn on the ignition, the valve closes from normally open with ignition off, start it up and it stays closed for less than 3 seconds, then goes to fully open. No manner of RPM makes any changes to the valve after the above occurs.

This includes all the way to redline. I either have it hooked up backwards or it's not working right or both.

Again I wish someone with a known properly operating bike would confirm operation!


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I can confirm that having 2x 2011 F4's side by side that the valve is closed or at least partly closed at idle. 1 F4 valve intact other F4 valve disabled. Obviously the disabled one was louder at idle. Don't know anything else apart from that, sorry.
 

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Yes,you can dissconnect the cables and tie them safely out of the way.The valve should be in the open position.Ride the bike to check how it's running.
 

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exhaust valves

It is not a noise thing.....those are found in the muffler (think Honda and BMW).
Anyone who wants to argue it is not for power delivery tuning just needs to look at the Aprilia SBK bikes and most of the MotoGP bikes.
well Ed, its only a restriction to flow, but there is a better reflection of the energy wave when its closed more......at low engine speeds......it might improve bottom end a bit....if properly configured....

oh, and it can improve fuel economy too.......back pressure does that

but you're talking race bikes, right?

doesn't sound like what they want does it?

you see this crap on any other race vehicle????

is it on F1, Indy cars or NASCAR????? of course not

what they need to do is shorten the pipe at higher rpms.....and certainly not like the stupid TTS on Tambos

one of E. Weber's rules.......nothing within 1 1/2 D of the air horn.....OOPS.....it disturbs air flow......no shit?

and who fueled more World Championship race motors than E. Weber??????

nobody :drummer:


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