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Discussion Starter · #1 ·
A bit of a noob, so apologize in advance for my ignorance.

With that said, I have been experiencing abrupt loss of power at higher rpm, around 11-12k. It’s like hitting a rev limiter where power just cuts off quickly. Even in neutral. Running thin. No issues in lower rpm.

Before bringing it into the shop, I tried troubleshooting by soldering my kickstand sensor (was told this happens), but that didn’t fix it. Now to the shop… I asked them to test fuel pump, which tested well. Looking a bit deeper the mechanic noted that one of my throttle body butterfly valves is stuck open. He said the electric motor / actuator (?) is likely worn and needs to be replaced. The kick to the nuts is that you can’t buy this part separately, it comes WITH the throttle body. He also recommend I change the “primary and secondary TPS sensors”.

I’ve seen some used throttle bodies for sale on eBay for $350CAD. They don’t look great. Unknown mileage. But buying new is like $1300+ CAD. A bit hesitant to buy new being that it’s a 2007 750. But relative low kms for its age (22k).

First, I’m confused about the “secondary TPS sensor”. Is this not the STVA? They gave me the wrong part number so I can’t confirm.

The primary TPS sensor and actuator / motor seems to be included in the throttle body itself, for new and most of the used products I see. Are the 600s and 700s interchangeable? Does the electric actuator/motor commonly die? Not sure if I should shell out for new one. I can’t find these for sale in their own, assuming that is the actual problem. The salvage yards I’ve spoken to say they wouldn’t sell them separately. If I bought a used throttle body, should I just replace the whole thing? Fuel rail and all? What level of difficulty is that job? Do the sensors need to be recalibrated or anything?

Lots of info. Just looking for some guidance, confirmation what best value way of moving forward is.

Thanks in advance.
 

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Im a little confused by this so I will start with a question.
You say one of the butterfly valves is stuck open. Are you referring to an individual one or a row set of them? Each set is linked so I can't see how just one is stuck open.

Used is probably the way to go but the 600 and 750 assembly are not interchangable. Some parts may fit but the sizing of others won't work properly.
 

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Discussion Starter · #3 ·
Im a little confused by this so I will start with a question.
You say one of the butterfly valves is stuck open. Are you referring to an individual one or a row set of them? Each set is linked so I can't see how just one is stuck open.

Used is probably the way to go but the 600 and 750 assembly are not interchangable. Some parts may fit but the sizing of others won't work properly.
Just one of them, apparently… That’s how I understood it from the mechanic.

I see now that the throttle body is not interchangeable. These used items are saying different… Thought that seemed off. The part number is 13405-02H02. Not the same for a 600 same year.
 

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Discussion Starter · #4 ·
Im a little confused by this so I will start with a question.
You say one of the butterfly valves is stuck open. Are you referring to an individual one or a row set of them? Each set is linked so I can't see how just one is stuck open.

Used is probably the way to go but the 600 and 750 assembly are not interchangable. Some parts may fit but the sizing of others won't work properly.
Another thing to mention is that I’m not getting an error code. Shouldn’t I be if the valve(s) is stuck open?
 

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I can't see how just one valve is stuck open. There are two sets and both are on a independent shafts. Can you take off the airbox and be certain what's going on in there? It may be a lot easier of a fix than to replace everything.
What you want to do while your there is cycle the stva. They should open and close fully.
 

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The mechanic is either lying, very confused, or guessing. It's impossible as all 4 butterflies are linked together and cannot move independently. If one is stuck in one position, they will all be at the same position. You may best find another tech.

In the mean time find a factory service manual, read all you can about the FI to the point you try to understand what's going on. Then pass that info on to the tech you choose to work on your bike. Too many techs are unfamiliar with everything on every year, model an make of bike they may see. I'm in the biz and stick to one brand and a range of years that I fully understand. What I see out there, and done by supposed pros, is amazing.
 

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could the screw have came out and its just floating? no just stabbing at the wind here dunno that TB setup

you can check on the TB butterfly condition with the tools that come with the bike, its fairly easy, a long phillip is nice to have for the air filter screws..

lets see, 2k7 should be the seat, front tank bolt, prop tank, disconnect sensors, vent hose, and vacuum hose, loosen air filter screws each side through frame holes, wiggle out or away just enough to inspect butterflies.. reverse order... pretty easy this can be done on the side stand..
 

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Discussion Starter · #8 ·
I can't see how just one valve is stuck open. There are two sets and both are on a independent shafts. Can you take off the airbox and be certain what's going on in there? It may be a lot easier of a fix than to replace everything.
What you want to do while your there is cycle the stva. They should open and close fully.
ya I’ll open it up tonight and see for myself. Then report back.
 

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Discussion Starter · #9 ·
could the screw have came out and its just floating? no just stabbing at the wind here dunno that TB setup

you can check on the TB butterfly condition with the tools that come with the bike, its fairly easy, a long phillip is nice to have for the air filter screws..

lets see, 2k7 should be the seat, front tank bolt, prop tank, disconnect sensors, vent hose, and vacuum hose, loosen air filter screws each side through frame holes, wiggle out or away just enough to inspect butterflies.. reverse order... pretty easy this can be done on the side stand..
Screw came out of where? I’ve opened it up before a few times but have never messed with the TB or STVA. Will do tonight.
 

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Discussion Starter · #10 ·
The mechanic is either lying, very confused, or guessing. It's impossible as all 4 butterflies are linked together and cannot move independently. If one is stuck in one position, they will all be at the same position. You may best find another tech.

In the mean time find a factory service manual, read all you can about the FI to the point you try to understand what's going on. Then pass that info on to the tech you choose to work on your bike. Too many techs are unfamiliar with everything on every year, model an make of bike they may see. I'm in the biz and stick to one brand and a range of years that I fully understand. What I see out there, and done by supposed pros, is amazing.
it was a Suzuki dealer and the mechanic said he owns/owned a gixxer… maybe I just got confused about one valve. I’ll confirm here soon. And looking into it a bit more, the STVA is the electric motor that opens up these butterfly valves eh. I see these for sale used but they’re as much as the TB itself..
 

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You technically don't need the stva. I take them off every gsxr Ive owned. A remap certainly helps get the most out of taking them off but it's not mandatory. You just lose a little low end power, like driving around a parking lot speeds. Other than that they are a restriction. I forgot the exact rpm but they are wide open around 6k.
 

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1) If they're stuck open, you shouldn't have a power loss.
2) If you don't have a code, they shouldn't be stuck open.
3) The STV Actuator is different than the STP Sensor.
4) The TPS is not related to the STVA and STPS function.
5) Yes, the sensors need to be calibrated.
6) A mechanic worth their salt could do this diagnosis in their sleep. Your mechanic is ignorant.

At this point, everything you've said (if true) points to a faulty ECM.
 

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You technically don't need the stva. I take them off every gsxr Ive owned. A remap certainly helps get the most out of taking them off but it's not mandatory. You just lose a little low end power, like driving around a parking lot speeds. Other than that they are a restriction. I forgot the exact rpm but they are wide open around 6k.

they don't just come off, a proper delete is best so you don't get FI codes..
 

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they don't just come off, a proper delete is best so you don't get FI codes..
Two screws each and the plates come right off. Do that four times. He isn't getting any codes now nor will he when he removes the plates. Leave the rest of the system intact and you will never get a code.
 

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Discussion Starter · #18 ·
Here’s a video of the TB: Throttle body valves issue?

They were closed when I popped off the tank. When I turn the bike on they open up fine but should they close right after? I understand this differs by year. Mine’s an 07.

I don’t see any loose screws. The mechanic did make an adjustment to the TPS sensor I believe. This has adjusted where the bike cuts power. Used to be at around 9k rpm or wot in 4th, but now it’s 12k. Even in neutral, if I rev it up that high it just blips at that rpm. Not a good experience at speed trying to pass on the road.
 

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Did you start it to see if they closed on there own? They should cycle open and closed when the key is turned but not started.
It's possible they are closing when you are riding and that's causing your issue.
 
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