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Discussion Starter · #1 ·
My 2004 GSXR 600 race bike has started showing a couple issues. Notably, no codes show up.
  1. Bike won't start without a touch of throttle, rpms hang, and bike dies at idle.
  2. Bike stops revving at ~4500 rpm, like it hits a limiter, and backfires. Here's a video of the rev issue: Revs stop .
Backstory: Bike has been sitting for a couple years since the last track event and I started to prep it for this season. Bike was running alright around the neighborhood before tearing into it. I did some routine maintenance after the test ride: valve adjustment, plugs, oil change, clutch refresh, brake fluid. After putting it back together it wouldn't start without a bit of throttle. I removed the fuel pump, cleaned some old gas from the tank and installed a new fuel filter. This didn't make a change. Checked plugs and they smelled a bit like gas but looked alright.

With the air box off the bike started right up and ran well. Reinstalled it and the connectors one by one and found that without the IAP sensor plugged in it started much easier. This throws a C13 code but otherwise idled and responded to short blips fine of 2-3k rpm, with the exception of rpms hanging (possible vacuum leak somewhere?). Swapped the sensor and see the same issues. Followed the manual and the sensor tests fine. I still need to check the wiring back to the ECU.

Thinking the problems were limited to start up I took the bike for a test ride and found that it stopped revving at ~4500 rpm, at which point it falls dramatically stops. When it gets to that point the bike burbles and backfires heavily. All of this is without showing an FI code. This feels like a two-step launch control. Back in the garage I can duplicate the issue in neutral. The fuel line isn't pinched and the pump passes flow testing.

There are some older threads that mention the STVA, CKP, or CMP but there's no codes showing up except for when I disconnect the IAP sensor. I'm at a loss for what could be next. Any help would be appreciated! Thanks.
 

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Dad Bod Super Mod
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Secondaries? Injectors clean?
 

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Doesn’t sound right at all. Even before 4500rpm.

You say the bike has been sitting. Is there any chance a rat has made a nice nest in the exhaust? Does this model have the servo on the exhaust? If so, does it cycle when turning the ignition on?

What condition is the air filter in?

Spray some wd40 on each header - is there one where the solvent doesn’t flash off as fast?
 

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Discussion Starter · #5 ·
Secondaries? Injectors clean?
Cleaned the injectors last night and got them all to spray equally. The spray pattern looked like two distinct sprays when I was expecting four, to match the openings in the nozzle.

For the secondary throttle I didn't test the motor as it turns out the PO removed the butterfly valves. Once things are running again those can be looked at for reinstallation.

Doesn’t sound right at all. Even before 4500rpm.

You say the bike has been sitting. Is there any chance a rat has made a nice nest in the exhaust? Does this model have the servo on the exhaust? If so, does it cycle when turning the ignition on?

What condition is the air filter in?

Spray some wd40 on each header - is there one where the solvent doesn’t flash off as fast?
Does it sound like it's not firing on one cylinder? ;) That is by design. The bike had been converted to a 450 by disabling one cylinder (fuel, spark, valves), all to fit into a specific racing class.

The bike had a full Leo Vince exhaust so if there was a servo it's not there anymore. The air filter is in decent shape. Before cleaning the injectors there was a discrepancy in cylinder temperature, as measured by a laser thermometer on the header. One (of the three functional cylinders) was 20+ degrees cooler than the others during warm up. That injector did take a few extra squirts to get an even spray pattern.
 

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Discussion Starter · #7 ·
The pump passes the flow test with ease. Still in fuel, someone else mentioned the possibility that the flow rate or pressure might drop as the rpms climb so I'll try to test the fuel pressure.
 

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I'd question that pump. Most healthy pumps will deliver well over the specification in about 5 seconds.
 

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My 2004 GSXR 600 race bike has started showing a couple issues. Notably, no codes show up.
  1. Bike won't start without a touch of throttle, rpms hang, and bike dies at idle.
  2. Bike stops revving at ~4500 rpm, like it hits a limiter, and backfires. Here's a video of the rev issue: Revs stop .
Backstory: Bike has been sitting for a couple years since the last track event and I started to prep it for this season. Bike was running alright around the neighborhood before tearing into it. I did some routine maintenance after the test ride: valve adjustment, plugs, oil change, clutch refresh, brake fluid. After putting it back together it wouldn't start without a bit of throttle. I removed the fuel pump, cleaned some old gas from the tank and installed a new fuel filter. This didn't make a change. Checked plugs and they smelled a bit like gas but looked alright.

With the air box off the bike started right up and ran well. Reinstalled it and the connectors one by one and found that without the IAP sensor plugged in it started much easier. This throws a C13 code but otherwise idled and responded to short blips fine of 2-3k rpm, with the exception of rpms hanging (possible vacuum leak somewhere?). Swapped the sensor and see the same issues. Followed the manual and the sensor tests fine. I still need to check the wiring back to the ECU.

Thinking the problems were limited to start up I took the bike for a test ride and found that it stopped revving at ~4500 rpm, at which point it falls dramatically stops. When it gets to that point the bike burbles and backfires heavily. All of this is without showing an FI code. This feels like a two-step launch control. Back in the garage I can duplicate the issue in neutral. The fuel line isn't pinched and the pump passes flow testing.

There are some older threads that mention the STVA, CKP, or CMP but there's no codes showing up except for when I disconnect the IAP sensor. I'm at a loss for what could be next. Any help would be appreciated! Thanks.
I just got a 05 750 amd it sat for awhile kid said it needed a tune up so I did it and mine cuts out around 5500 it almost sounds like a 2 step. I cant figure ut out for the life of ne so if you figure it out lmk I'm also throwing no codes maybe an fi code here or there but only for a sec
 

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Discussion Starter · #13 ·
Swapped in the spare pump and the same situation. The pump flows really well and hits that limit at 4500.

I'm also throwing no codes maybe an fi code here or there but only for a sec
Sorry to hear you're in the same situation. When it does throw a code are you able to see what it is?
 

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Swapped in the spare pump and the same situation. The pump flows really well and hits that limit at 4500.



Sorry to hear you're in the same situation. When it does throw a code are you able to see what it is?
No I threw it in dealer mode right after it popped up last time and it already was reading clear. Yea Idk to much about these yet but its so confusing
 

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Or if it happens consistently, just put it in dealer mode and leave it while you work through the issue.
 

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Or if it happens consistently, just put it in dealer mode and leave it while you work through the issue.
[/QUOTEyea thay to wasnt to sure if i could do that or not ill put it in dealer mode tonight and fuck with it see if I can get it to pop up because that would prob help me out knowing what its throwing, I appreciate it man thanks
 

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Dad Bod Super Mod
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Two ways you can attach a video.

Start your reply then click the picture button in the message banner at the bottom of the reply box. It looks like a postcard.

Drag your vid into the box.

Or, click in the box and select your vid from the list.

Or, click the camera button beside it and choose take picture.

Or, choose a pic from your gallery.

If you are on your phone open a reply, click the camera icon, record a video and hit sent.
 
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