GSX-R 1000 04 model

Anyone here pulled the exhaust control valve off one? I'm looking at
doing mine.

Fraser

 

You'll have to do more than that to get it passed as LAMS restricted!


BTH

 

No but it's just an electronically controlled valve in the exhaust
pipe - what exactly do you need to know? You'll need to replace the
collector pipe IIRC to remove it out of the system altogether if
that's what you mean.

JL

 

After a bit of googling I have found the info. Basically the valve is
there for emmissions reasons and for low end torque. Most people on
forums can't tell the difference. The reason I want rid of it is they
are a complete pain in the arse to set up. By getting rid of it you get
a ecu error and the bike goes into limp home mode. But by pulling a
wire on the ecu you get rid of the error. Result!!! A kilo of crap off
the bike and one less thing to go wrong.

Fraser

 

<sigh> You didn't do a lot of research if you think it's a kilo of
crap. (and I'd be very surprised if it weighed that much)

Most racebikes remove it because it doesn't add much value on the
track. On the road it's a different story. The Yamaha EXUP valve and
the later Suzuki equivalent (I forget their acronym - SRAD ?) create a
benefit for surprisingly little cost.

The benefit is a significant increase in low and mid range power
without costing much if any top-end. This is more important on a road
bike than a track bike and hence race teams will of course often
remove it usually in favour of an exhaust that will allow even more
gas to flow and give them even more top end.

Exhaust tuning has to balance peak power against low end grunt. The
low end is particularly useful on the road and allows you to not have
to do the gearbox shuffle you do on say a 250 2 stroke. A wide
powerband is more usable in the real world. The shape of the torque
and power curves are always a trade off - you take a little from down
here to add a bit up the top here etc. So in conventional tuning you
can get more mid range by taking a bit off the top - how ? In simple
terms you reduce the diameter of the exhaust pipe (yes it's more
complicated than that). A narrower pipe gives higher gas velocity and
prevents the gas slowing too much and hence not flowing out quick
enough to clear the cylinder. That's great at low rpm but obviously as
the rpm climb you end up putting a limit on how much gas gets out.

That's where exup et al come in - you basically get two exhausts for
the price of 'one plus a valve' - you get one optimised for low rpm
(valve closed and hence narrower pipe) and one optimised for high rpm
(valve open and hence bigger pipe).

If you take it off you basically take away a chunk of mid range to
absolutely no benefit. The only way you will get a benefit is if you
replace the exhaust with a full race system.

At least one manufacturer (MV Agusta) and I think a couple of others
(Yam and Aprilia IIRC) have the same thing at the intake side -
variable length intakes - which does exactly the same job - maximises
air flow at lower velocities(1) and then opens out to let more air
through at high velocities. It's somewhat common on cars.


JL
1 low velocity is a combo of both rpm and throttle position - think
about opening a carbed motor wide open at low throttle and the way it
bogs down - that's because the velocity gets slow - big orifice and
not much pre-existing movement to suck it along

 

Seen dyno charts and it basically does **** all. It is there for noise
and pollution regs. There is a TINY bit of low end torque lost by
removing it but on a 1000cc sports bike it is bugger all. Heaps more
info here:-
http://www.gixxer.com/forums/showthread.php?t=87741&highlight=set+valve

Not sure if you need to register.

Fraser

 

If all this info is available on a gixxer forum, why didn't you just ask
the original question there?

Nev..
'07 XB12X

 

I used to have a 2001 model. The valve cables failed after 2 years
and I did the mod.
However, on billard board table roads like the NT, you wouldn't notice
it, but on
goat tracks like you have in SA, the 6k and 10k power peaks that
appear without
the value rev filtering become a bit dangerous when you hit big F.O.
bumps. Can
easierly result in a high side (the gixxers are notorious for side
siding people in
the hills). Those power peaks were pretty good fun though

I ride a KTM SD now and go harder.

 

And you didn't read it either did you from this guys post, with chart

===========
tank34
Roll On Champion


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Join Date: Mar 2004
Location: The Wilderness
Motorcycle: BMX with 2 flat tires
Posts: 3,619

Re: One Last Time...The final set-valve thread
Maybe it's just me... but I'm a bit of a stickler for details.
According to JeffW's chart, which he posted many moons ago, there is
torque loss at 3k rpm (without a remap, from what I can gather).
Now- maybe it's not useful, and no-one cares, but I think when people
come here for explanations, we should try to be accurate in the
responses. Gives the forum a better reputation.
Now, I have no doubt that a decent exhaust and a good re-map would fix
that hole.
I just think it's a bit misleading to conclusively say the SET valve
only reduces noise on a stock bike.
(I dunno, some people think cucumbers taste better pickled.)

Does someone have the sport rider results to refute this?
====================

Obviously I can't attach the jpg (and I can't view it without
registering which I ain't gunna do)

Bottom line you get no benefit from removing it unless you change the
headers and dyno tune for the higher gas flow. If you do that you'll
prob end up with more up top and less down low (assuming it's a higher
flow system which you would expect it to be).

JL

 

To annoy you and to slow the death of usenet. : P

Fraser