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07 GSX-R 1000 wont rev past 6-8k

2600 Views 25 Replies 4 Participants Last post by  AllBlackWhip
I've been looking around for a fix almost everywhere. My bike sometimes lets me fully rev while in neutral, but sometimes not even past 11k.

When I ride with gears, it usually wont rev past 6-8k rpm and bogs down. Feels like it doesnt get enough fuel? I also installed SP Quickshifter + Launch Control kitbon this bike.
The bike hadn't this kind of issue before I tore it down before winter. I unplugged almost all the wirings and exhausts etc.
My previous post is below in there as name Coolant leak + white smoke. It had a minor coolant leak from the cooler and got fixed it by now.

However I have done the following in order to eliminate this issue:
  • Disassemble the launch control kit
  • Changed back the old different kind of air filter than the new one
  • Borrowed a fuel pump whichs fuel filter was cleaned
  • Checked ignition coils, looks fine
  • 2 fuel injectors were broke, replaced them
  • It also had and has C28 error due to me disassembling the 2nd throttle body (huge mistake). Took the butterfly plates off. C28 is still in there but ordered STV Eliminator kit
  • Spark plugs seemed to be fine. A mechanic said it sounds normal and it does
  • Checked for air leaks, didnt seem to find any

Any ideas?

Thanks in advance!
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Bogging down is most often a fuel pump filter issue. Check the flow rate per the service manual procedure.
Bogging down is most often a fuel pump filter issue. Check the flow rate per the service manual procedure.
I tested the bike with a fuel pump that had a filter which was cleaned. I even saw that filter by myself and that repair shop borrowed me that one, didn't fix with it.

I've been thinking about if the problem exists in the ECU? It has been flashed and I notice that when I release the throttle, it "decelerates" more aggressively than before. At least that's how it feels like.
When riding to turns and releasing the throttle, it feels really scary because the throttle won't respond quickly enough.

But yeah, I should check out the flow rate from the manual.

EDIT: However the mechanic who took care of this bike before, said that the gas tank had full of moisture. But it was strange that with another fuel pump it didn't start to work. So could the problem lay elsewhere? The fuel injectors were fine and checked.

Don't really know if it "bogs down" but kinda being like a limiter.


I had full throttle in the video.
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The Suzuki service suggested me to use fuel injector cleaner and check if there is rust inside of the gas tank. Could be the problem.
"I even saw that filter by myself"
That sounds like you saw the strainer, not the filter. It's difficult to see any part of the main filter element.

The ultimate test is to measure the fuel pressure while you're riding & bogging. But that takes a bunch of hooking things up. The flow test is much easier and is usually definitive. Fuel injector cleaner will remove injector deposits but it will take several tankfuls of gas to see results.

The second most common cause of bogging/rev limiting is a problem with the secondary throttle system, either they aren't opening fully or the secondary injectors aren't working or are clogged. Your video sounds more like that. You can watch the injectors cycle when you turn the ignition on. It's also possible to swap the primary and secondary injectors but the screws that mount the fuel rail have a habit of sticking in the throttle body. But I don't know why the secondaries would clog and not the primaries, so bad electrical connections would be more likely. However electrical issues should cause a fault code. You said that you have C28. I can see the red fault light and, barely, FI being displayed in the video. You have to get rid of that. You're operating in fail-safe mode.
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"I even saw that filter by myself"
That sounds like you saw the strainer, not the filter. It's difficult to see any part of the main filter element.

The ultimate test is to measure the fuel pressure while you're riding & bogging. But that takes a bunch of hooking things up. The flow test is much easier and is usually definitive. Fuel injector cleaner will remove injector deposits but it will take several tankfuls of gas to see results.

The second most common cause of bogging/rev limiting is a problem with the secondary throttle system, either they aren't opening fully or the secondary injectors aren't working or are clogged. Your video sounds more like that. You can watch the injectors cycle when you turn the ignition on. It's also possible to swap the primary and secondary injectors but the screws that mount the fuel rail have a habit of sticking in the throttle body. But I don't know why the secondaries would clog and not the primaries, so bad electrical connections would be more likely. However electrical issues should cause a fault code. You said that you have C28. I can see the red fault light and, barely, FI being displayed in the video. You have to get rid of that. You're operating in fail-safe mode.
Could be the strainer, he removed the bottom of it and I saw a thing that looked like a coffee filter 😅
About my secondary throttle system, do you mean the butterfly plates ain't opening? Because I removed them already.

I'm not even sure how to do the fuel flow test after checking from the manual.

But if the C28 causes me to get the fail-safe mode, then wouldn't it be able to rev to 11k to 15k rpm in neutral?
I am getting rid of it as soon as the eliminator box arrives, that eliminates the C28 fault code. Healtech also stated this: "Note: After installation, we recommend having the AFR (air-fuel ratio) of the engine checked by a dyno center and adjust if necessary."

So this should be done as well?

The service manual is vague on exactly what happens, saying only "FI system is provided with fail-safe function to allow the engine to start and the motorcycle to run in a minimum performance necessary even under malfunction condition." and "But, the engine running condition is not complete, providing only emergency help (by fail-safe circuit)." That could easily mean a lower rev limit.

Unless you removed the secondary throttle shaft, you should be able to see it turning. I think it goes through a procedure on startup to determine the limits of travel. No butterflies probably screws that up.

The filter is on the top, not the bottom.
The service manual is vague on exactly what happens, saying only "FI system is provided with fail-safe function to allow the engine to start and the motorcycle to run in a minimum performance necessary even under malfunction condition." and "But, the engine running condition is not complete, providing only emergency help (by fail-safe circuit)." That could easily mean a lower rev limit.

Unless you removed the secondary throttle shaft, you should be able to see it turning. I think it goes through a procedure on startup to determine the limits of travel. No butterflies probably screws that up.

The filter is on the top, not the bottom.
That could explain it, because it really feels more like of a rev limiter.
I didn't remove the shaft but only the butterflies. Before that, the butterflies only shook around (trying to open, but they couldn't?). Then when I put the wrong wirings in the actuator, it moved them a little bit but not completely. And this was really the incorrect cables for it, but it fit since I just have enough length to connect them.

I'll update this once I have the eliminator and if the problem still exists after that.
have you tried replacing rectifiers ?
No, but would faulty one drain the battery dead?
The C28 didnt disappear after installing the Healtech STV Eliminator. Do I still need to use Suzuki OBD tool to reset the code or what?
I'm unfamiliar with the Healtech. The C28 will automatically go away if faults in the secondary throttle are corrected. So I don't see why that shouldn't also happen with the Healtech. Does it connect to both secondary connectors?
I'm unfamiliar with the Healtech. The C28 will automatically go away if faults in the secondary throttle are corrected. So I don't see why that shouldn't also happen with the Healtech. Does it connect to both secondary connectors?
Yes to both of them. Could the problem lay in the ECU then?
How about in the wiring to them? Early on here you said that you were fiddling with it.
How about in the wiring to them? Early on here you said that you were fiddling with it.
I actually know the reason. My local vendor sold me the STVE-01 version which is incompatible with my bike, it should be the STVE-10 version. They had the incorrect eliminator up for sale stating that it fits my 07 GSX-R. Have to order the correct one and return the incorrect one and wait for another 3 weeks. :rolleyes:
It fits. It just doesn't work.
Yeah it's strange that the connectors are exactly the same, but Healtech confirmed in email that STVE-01 version is incompatible with 07 GSXR 🤷‍♂️
The STV Eliminator arrived and the FI light finally disappeared, but it still has no power. Had the fuel pressure test done by a motorbike service which has experience of Suzukis. They said that they believe it's the FI light that cuts the power, but now since it's gone it still won't rev past the x RPM's. I even used twice the fuel injector cleaner and that didn't make difference except for big flames when using launch control :D

Could there still be some problems with the STV, like a hidden error that needs to be cleared out / disable the entire system, even with no FI light and the eliminator box connected?
Or could it be air leak? I remember that the ram air tubes didn't fit as tight as they were before I removed them. The service guy also stated that sometimes while idling and measuring the fuel flow it might look okay, but while revving at higher RPM's the result could then change. But I can't rev this bike up unless on neutral and everytime I do so, it first lets it rev to maybe 13k rpm, then when I let go off the throttle and do it again, then it goes to max of 11k rpm. Air leak or still problem with the fuel?

EDIT: I don't remember if I mentioned but 2 months ago when I had this bike at the service for the first time, they noticed that the fuel tank had a lot of condensed water but they measured the injectors and they were okay? Another service guy said that if there is rust inside of the tank, it could cause issues. I even used another fuel pump so that's not the problem.
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Inserted a new fuel filter and sealings but it still didn't solve the problem. Previous owner hinted about valves, if they could be the problem? These are the only options which could cause it: spark plugs, ignition coils, ECU(?) or the valves. Any other suggestions?

EDIT: Also bought another fuel tank and used other fuel pump system which still made no difference. Air leaks shouldn't be there anywhere now because the ram air tubes are fit and all the clips for throttle body and air box are connected and firmly tight.
What exhaust do you have? The EXCV valve will choke the bike if it doesn't fully open.
What exhaust do you have? The EXCV valve will choke the bike if it doesn't fully open.
I have the original exhaust with GPR mufflers and the catalyst is replaced with Y-pipe. I thought about this and when I give full throttle, I don't see it moving but is this the condition where it should fully move? When I turn on the key it moves just a little bit but a Suzuki service guy said that it works if it even moves a little bit? But never seen it fully move when revving.

Also as a side-note which I forgot to mention is that the primary and secondary injectors are tested and they all run fine.
But I dismantled the EXCV system when I removed the exhaust and then forgot to fully reassemble it before I took it into a service. They however assembled it back, but I don't know if they assembled it incorrectly.
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