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Discussion Starter · #1 · (Edited)
Hello All,

I am having an issue with my bike(2018 gsxs) shaking in first gear and low rpms. When i try to keep the bike moving between 10-15mph it shakes abruptly. See video. The idle now fluctuates from 1000-1250 rpm intermittently. It used to stay at 1000rpm.

I installed new headers, blocked the pair valve system and flash the ECU to clear the codes and improve fueling. I also have a quick shifter. I didn't notice any changes when i installed the new headers on and have not done the flash. Once i got it flashed, i noticed this issue. I already sent the ecu back to 2w2d and reinstalled the issue but whatever they did, it didn't improve my situation.

Is anybody else experiencing this? Certainly regretting the flash.

My friend has a 2016 stock bike and it rides much better at low rpm.
 

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I have the same thing after flashing with doing a decat. A dyno tune will be your answer as they are mostly guessing with a reflash unless they deal with this exact bike all of the time. Mine will be going in soon.
 

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Are you using the stock muffler as well?
No I have a lextek XP8C. Before that I had a scorpion serket. A little less juddering with the scorpion I believe. I put on a little knock off austin racing can looking slip on and the performance went out the window. Felt like the bike lost half the power and went back to surging too. Shows how much the backpressure changes with a slip on. I'm sure with a proper dyno tune the little end can would be fine.
 

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Discussion Starter · #6 ·
No I have a lextek XP8C. Before that I had a scorpion serket. A little less juddering with the scorpion I believe. I put on a little knock off austin racing can looking slip on and the performance went out the window. Felt like the bike lost half the power and went back to surging too. Shows how much the backpressure changes with a slip on. I'm sure with a proper dyno tune the little end can would be fine.
I just bought a arrow pro race exhaust. Let's see how it goes. Will receive it in a coupe of days.
 

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Hello All,

I am having an issue with my bike(2018 gsxs) shaking in first gear and low rpms. When i try to keep the bike moving between 10-15mph it shakes abruptly. See video. The idle now fluctuates from 1000-1250 rpm intermittently. It used to stay at 1000rpm.

I installed new headers, blocked the pair valve system and flash the ECU to clear the codes and improve fueling. I also have a quick shifter. I didn't notice any changes when i installed the new headers on and have not done the flash. Once i got it flashed, i noticed this issue. I already sent the ecu back to 2w2d and reinstalled the issue but whatever they did, it didn't improve my situation.

Is anybody else experiencing this? Certainly regretting the flash.

My friend has a 2016 stock bike and it rides much better at low rpm.
I had the same issue on my katana after the same mods + dyno tuning. Recently I changed the stock muffler for an SC project and it vastly improved the low end judder/lack of power. I can't promise you'll experience the same but for me the slip on made a surprising difference
 

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Discussion Starter · #8 ·
I had the same issue on my katana after the same mods + dyno tuning. Recently I changed the stock muffler for an SC project and it vastly improved the low end judder/lack of power. I can't promise you'll experience the same but for me the slip on made a surprising difference
I am frustrated. I didn't know about this. 2w2d the tuner has a video of a Dyno tuned katana. They were able to get 147hp at the wheel with the stock exhaust and cat on. Recently i sat on one. Nice bike.
 

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I am frustrated. I didn't know about this. 2w2d the tuner has a video of a Dyno tuned katana. They were able to get 147hp at the wheel with the stock exhaust and cat on. Recently i sat on one. Nice bike.
Mine dynod at 147 with mods but that's without a flash tune and only pcv. It had plenty of oomph but for some reason really struggled under 3k rpm until I swapped the slip on. I think the stock headers use the exhaust valve to get more torque at low rpm
 

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Discussion Starter · #10 ·
Mine dynod at 147 with mods but that's without a flash tune and only pcv. It had plenty of oomph but for some reason really struggled under 3k rpm until I swapped the slip on. I think the stock headers use the exhaust valve to get more torque at low rpm
Dyno tune and flash in my area cost between $600-$800 not cheap at all. If the arrow helps our significatively I will leave it like that if not will get it Dyno tuned but I learned my lesson.
 

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Discussion Starter · #12 ·
Mine dynod at 147 with mods but that's without a flash tune and only pcv. It had plenty of oomph but for some reason really struggled under 3k rpm until I swapped the slip on. I think the stock headers use the exhaust valve to get more torque at low rpm
I unblocked the pair valve hose and now it is back to smooth. It improved a lot. Check that in yours.
 

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I unblocked the pair valve hose and now it is back to smooth. It improved a lot. Check that in yours.
I just posted this in your other thread. I'll put it here for anyone reading this thread and not that one...

Unblocking the PAIR valve fixed it? There's tens of thousands of Suzuki's with blocked PAIR valves running around every day without experiencing the shuddering at low speed/low RPM as your video depicted. Here's my opinion on what was likely the problem in your case.

The PAIR valve injects fresh air into the exhaust stream in an attempt to help eliminate any unburnt fuel from exiting the exhaust and entering the atmosphere. It doesn't have any impact on how the engine runs, as it's operation comes into play after combustion has taken place, not during.

How did you block it? Did you simply remove the single hose connecting the air box to the valve and cap each end, or did you remove the valve completely and install blockoff plates on the engine?

Either way, there's only one way I can see the problem you were experiencing as being caused by having the PAIR blocked and then resolved by unblocking it. My guess is that you either blocked it off improperly altogether, or you did it properly, but had a vacuum leak at one of the ports. If this was the case, undoing your work and reverting back to stock and seeing the issue resolved would make it seem as if the block-off itself caused the problem, when in fact it was just a leak somewhere.

A vacuum leak will exhibit the lumpy idle and poor performance at low RPM, which are the two issues you described.
 

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Discussion Starter · #14 ·
I did not use the plates. I blocked it putting a rubber cap in the line to seal it. Similar to how people use the marble. The cap blocked it fully as an there was no exhaust backfire at all. Not that it is unblocked there is the characteristic sound in the exhaust that comes up when the pair valve is doing it's job. The tuner told me just to unblock it and it will become smoother at the expense of some peeformance. It actually did exactly what he said so i do not think it was blocked incorrectly, i guess this is something expected with their flash. He knew the exact result i would get. I may try a different flash because i really want the pair valve to be blocked. I don't like the sound it know makes during deceleration.
 

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I did not use the plates. I blocked it putting a rubber cap in the line to seal it. Similar to how people use the marble. The cap blocked it fully as an there was no exhaust backfire at all. Not that it is unblocked there is the characteristic sound in the exhaust that comes up when the pair valve is doing it's job. The tuner told me just to unblock it and it will become smoother at the expense of some peeformance. It actually did exactly what he said so i do not think it was blocked incorrectly, i guess this is something expected with their flash. He knew the exact result i would get. I may try a different flash because i really want the pair valve to be blocked. I don't like the sound it know makes during deceleration.
Yeah, maybe it's something particular to their flash. I'm not sure what they could have done with the tuning to cause the poor idle and shudder at low RPM which happens only when the PAIR valve is blocked, but who knows. Unfortunately, I've read posts from other members here who experienced various problems with their bikes after getting a 2WDW flash. Ultimately, I think you're on the right track when considering having someone else perform a reflash. It sucks to have wasted the time and money with 2WDW, but you won't be happy unless you get your bike the way you want it.

There's two places I'd recommend. The first is Dano's Performance in California. He flashed my 2020 GSX-S1000 ECU recently and the difference in performance before and after is night and day. Even with all the modifications, the bike starts, idles, and runs 100% better then it did when brand new and pulls like a freight train. His customer service is first rate and he'll call you once he receives your ECU in order to go over all the details of your bike and what you're looking to get out of the flash. Second choice would be Chris Moore of Moore Mafia in South Carolina. You may be familiar with his tuning videos on YouTube. I don't have firsthand experience with his flash on my own bike, but I do have a couple friends who have had him flash theirs, along with another who had him tune his bike in person. All three guys are satisfied with his work.
 

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Discussion Starter · #16 ·
Yeah, maybe it's something particular to their flash. I'm not sure what they could have done with the tuning to cause the poor idle and shudder at low RPM which happens only when the PAIR valve is blocked, but who knows. Unfortunately, I've read posts from other members here who experienced various problems with their bikes after getting a 2WDW flash. Ultimately, I think you're on the right track when considering having someone else perform a reflash. It sucks to have wasted the time and money with 2WDW, but you won't be happy unless you get your bike the way you want it.

There's two places I'd recommend. The first is Dano's Performance in California. He flashed my 2020 GSX-S1000 ECU recently and the difference in performance before and after is night and day. Even with all the modifications, the bike starts, idles, and runs 100% better then it did when brand new and pulls like a freight train. His customer service is first rate and he'll call you once he receives your ECU in order to go over all the details of your bike and what you're looking to get out of the flash. Second choice would be Chris Moore of Moore Mafia in South Carolina. You may be familiar with his tuning videos on YouTube. I don't have firsthand experience with his flash on my own bike, but I do have a couple friends who have had him flash theirs, along with another who had him tune his bike in person. All three guys are satisfied with his work.
My idle is still a bit over 1k but the bike sounds better, calmer. The tuner said that my idle will difer from stock because of the difference in back pressure but others here kept the same idle rpm so i am unsure about that as well. I am totally surprised by the pair valve situation because as you said i was always under the impression that it would not affect performance since the system just remove gases. The tuner said they don't mess up with rpms at 1400-2000 range so a perhaps that area has to be worked out in their flash for the pair valve to be removed. I have contacted Danos already.
 

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My idle is still a bit over 1k but the bike sounds better, calmer. The tuner said that my idle will difer from stock because of the difference in back pressure but others here kept the same idle rpm so i am unsure about that as well. I am totally surprised by the pair valve situation because as you said i was always under the impression that it would not affect performance since the system just remove gases. The tuner said they don't mess up with rpms at 1400-2000 range so a perhaps that area has to be worked out in their flash for the pair valve to be removed. I have contacted Danos already.
My bike idled just above 1k RPM even when totally stock/brand new. It did sound a bit more smooth before I added the full exhaust and flash, but that's because the factory exhaust had enough restriction to smooth out the small fluctuations in sound that come from each cylinder firing at idle. The new exhaust has little restriction and those fluctuations can now be heard. Watching the tachometer, the RPM holds steady right where it did before the exhaust and flash, it just has a more aggressive sound.

Good luck with Dano's and nice looking bike!
 
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