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I finally moved, now I have a garage so I don't have to dismantle my bike on the footpath anymore. First thing I did, I removed the STV plates.
Took me 30 minutes. I suggest if somebody wants to do it, not to take the throttle bodies out completely. Just undo some connections, lift them enough to put a clean rug in the intake ducts not to have a screw fall in the cylinder.
Careful the screws are loctited, and typical suzuki cheese consistency, so you have to use a good screwdriver and push hard.
Once you take them out, clean the bodies from the blue loctite paste.
Reassemble everything, the bike still thinks the STVs are there doing their thing, no error code or anything.
fast idle works perfectly.
Then I went for a ride and WHY DID THEY PUT THE STVS IN THE FIRST PLACE!!!!!
Bike is more responsive, the first thing I noticed is the engine braking is much weaker. From closed throttle there is less jerkiness (should be the opposite), I can now cruise in 6th gear at 2.5k rpm! WOT the response is different. Probably less linear (that dip at 5k rpm is a bit more accentuated) but I was very pleasantly surprised when my bike power wheelied in 2nd gear. I mean all the way up. Never happened before without clutch.
And then thanks to Teeriver's Fuelbot I noticed a good decrease in fuel consumption, from 8L/100km (29mpg) to 6.2L/100km (37mpg) on average, which tells me my bike was running rich.
My advice: do it. I can't see any downsides.
 

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Potential downsides:

less HP
less linear throttle response
idle problems
cold start issues
Actually, if you just pull the plates and leave the shafts/motor/sensor in place the cold start is unaffected and fast idle still working as normal. Idle is likewise unaffected. The throttle response could very well be less linear, you don't have the STV's to cover you if you open the throttles too far too soon...but it's not bad and the light throttle power normally much improved.

The STV's were installed mostly to make it pass noise emissions (IMHO) and to cover a ham hand on the throttle with the engine at very low rpms. If you don't need the ability to whack them WFO at 2K in 6th...the STV's won't be missed.
 

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More out of curiosity. Any chance of this making things dangerously lean? I want to do this but I don't and any way to change the mixture at the moment.
 

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Discussion Starter #5
Potential downsides:

less HP
less linear throttle response
idle problems
cold start issues

less hp: don't see how since at wot the stvs are fully open so no diff.
less linear: maybe but i don't care, if i wanted linear i would have bought a bandit.
idle problems: not at all
cold start: see recoilrob's comment.

for me it's a win win, especially the smoothness at low rpm. couldn't ride under 3.5k rpm before.
 

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More out of curiosity. Any chance of this making things dangerously lean? I want to do this but I don't and any way to change the mixture at the moment.
I sincerely doubt you have to worry about it getting too lean by STV removal. The ECU's seem to be set pretty rich...at least on the 1K's and I'd imagine the 650's would be similar. At light throttle settings, if it still runs....it's not too lean. Only at higher throttle settings do you need to worry about being lean and doing damage....and the STV's should be out of the picture by then anyhow.
 

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I sincerely doubt you have to worry about it getting too lean by STV removal. The ECU's seem to be set pretty rich...at least on the 1K's and I'd imagine the 650's would be similar. At light throttle settings, if it still runs....it's not too lean. Only at higher throttle settings do you need to worry about being lean and doing damage....and the STV's should be out of the picture by then anyhow.
Sounds good to me. I went ahead and took them out yesterday. Noticeable improvement in smoothness in the lower rpm's.
 

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Sounds good to me. I went ahead and took them out yesterday. Noticeable improvement in smoothness in the lower rpm's.
Good!:) I've been on an 'anti-STV' rant for a few years now. Work of the Devil they are. But using them makes perfect sense to allow the manufacturer to easily pass noise standards in the various places the bike will be sold by merely adjusting the ECU and not being forced to change major hardware. Plus, on the 1K's, the STV's won't open much at all in 1st or 2nd gear which limits the power (and wheelies) which makes the bike 'friendlier'.

You'll likely notice the intake howl will be louder now, and the difference you hear is how much they were restricting you. Just be careful with the throttle and enjoy all the motor has to give you.
 

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Good!:) I've been on an 'anti-STV' rant for a few years now. Work of the Devil they are. But using them makes perfect sense to allow the manufacturer to easily pass noise standards in the various places the bike will be sold by merely adjusting the ECU and not being forced to change major hardware. Plus, on the 1K's, the STV's won't open much at all in 1st or 2nd gear which limits the power (and wheelies) which makes the bike 'friendlier'.

You'll likely notice the intake howl will be louder now, and the difference you hear is how much they were restricting you. Just be careful with the throttle and enjoy all the motor has to give you.
I did notice that increase in noise. I have a shortened snorkel. Removing it was louder than removing the stv's. I'm getting a a/f meter when funds permit it. I would also like to get a device to manipulate the fueling. I read your work with the Suzuki specific one. I'm wondering if I can adjust all the smae parameters with a power commander?
 

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The PC's work differently than the TEKA, and I'm torn as to which is the better way to proceed. There ARE PCIII's that will not mess with the sub 4K fueling, and this is required to remain legal in CA....and might be a good idea anyhow.

Biggest thing, now that we're talking about the SV's, is they have a 'dual operating system' of sorts. During light throttle running, the ECU is watching the manifold pressure sensor/s and rpm mostly (speed density) to determine the proper fueling, but then at higher loads/rpms it switches to Alpha/N (throttle/rpm) and this is mostly where/how the PC's operate AFAIK. I've NOT seen anyone match the gas mileage the stock ECU operation after TEKA tweaking can get with a PCIII. THinking this is because of the PC losing the speed density ability which is more efficient at cruise conditions....but can't swear on it.

I've not tinkered with a PCIII, but HAVE the TEKA, and it works well. Watching the A/F meter, it's clear the bike doesn't work like a modern car and many compromises are being made. Mine goes fat when it encounters headwind! Gusts hitting show up on the A/F by making it dip rich....which I'm thinking is the fairing pressurizing the intake a little which throws the intake pressures off a little and the ECU responds in kind. Not a big deal, it's just you have to be lenient in your tuning and allow the bike to wander around a bit.:)
 

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I finally moved, now I have a garage so I don't have to dismantle my bike on the footpath anymore. First thing I did, I removed the STV plates.
Took me 30 minutes. I suggest if somebody wants to do it, not to take the throttle bodies out completely. Just undo some connections, lift them enough to put a clean rug in the intake ducts not to have a screw fall in the cylinder.
Careful the screws are loctited, and typical suzuki cheese consistency, so you have to use a good screwdriver and push hard.
Once you take them out, clean the bodies from the blue loctite paste.
Reassemble everything, the bike still thinks the STVs are there doing their thing, no error code or anything.
fast idle works perfectly.
Then I went for a ride and WHY DID THEY PUT THE STVS IN THE FIRST PLACE!!!!!
Bike is more responsive, the first thing I noticed is the engine braking is much weaker. From closed throttle there is less jerkiness (should be the opposite), I can now cruise in 6th gear at 2.5k rpm! WOT the response is different. Probably less linear (that dip at 5k rpm is a bit more accentuated) but I was very pleasantly surprised when my bike power wheelied in 2nd gear. I mean all the way up. Never happened before without clutch.
And then thanks to Teeriver's Fuelbot I noticed a good decrease in fuel consumption, from 8L/100km (29mpg) to 6.2L/100km (37mpg) on average, which tells me my bike was running rich.
My advice: do it. I can't see any downsides.
Why am I just now hearing of this?! I've been on the forum for several years and have done quite a few useful mods I read about here, but this one is news to me. Does my 05 naked have these on it? If so, they'll be gone by the end of the weekend. Gotta love free stuff.
 

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Why am I just now hearing of this?! I've been on the forum for several years and have done quite a few useful mods I read about here, but this one is news to me. Does my 05 naked have these on it? If so, they'll be gone by the end of the weekend. Gotta love free stuff.
It sure does. I think I will take mine off as well and give it a try.

Take off the air box. The valves or plates that are on the intake (fresh air) side of the throttle bodies are the secondary throttle valves.
 

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Discussion Starter #16
Take off the air box. The valves or plates that are on the intake (fresh air) side of the throttle bodies are the secondary throttle valves.
make sure you don't drop anything down the intake while you take them out. The throttle valves should be closed under anyway, but a clean cloth would help.
 

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I just pulled the STV plates off on my 2003 650. I only road it a couple of miles in traffic. With the stock air filter and with the snorkel in place I didn't notice any additional intake noise. At least none that I could hear while wearing a helmet. I did not notice a big increase in power anywhere. But it ran great. It felt really crisp and responsive. I tried in second and higher gears to get a bog out of it and it didn't bog anywhere. Unless I notice a bog after I put more miles on it they are not going back in.

Thanks for the nudge to pull the plates out!
 

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RR. Did you notice-need a throttle body rebalance after removing the STV`s? Air bleed adjustment?
Nope. I'd gone in gingerly by first adjusting the STV's to maximum open (there is some play in the sensor so you can open them up a bit), then drilled holes to progressively open them. Liked every step, so finally pulled them all the way out, then took out the shafts/motor et al and put in one of D'Ecosse's emulators to keep the ECU happy. Won't ever go back to STV's...no way.:)
 

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Is there anything to gain by pulling the shafts and motor that runs them? Or did you just pull them because they are no longer needed?
 

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Can the next person take pics for a how to? Not completely mechanically declined but I learn as I go, so I don't know what stv plates are, but this sounds like something worth doing
 
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