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Discussion Starter #1
So I have a K7 GSXR 1000. Just got it and all of the sudden its misfiring below 5500rpm. The misfire is coming from cylinder 4 (right side). I've replaced the spark plugs with NGK Iridiums and checked all coils for spark (all are good). After running it for a bit the right side spark plugs is wet. Stock bike with a shorty MF(?) slip on. What else could I check that could correct this issue? TIA
 

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Welcome.

I'm assuming that you have also swapped ignition coils to eliminate them as a problem?

I had a similar issue with my K6 750. The bike would start and run fine but when going back to idle, it would be on three cylinders. A few minutes later it would start up, run fine, repeat. It turned out the injector on one cylinder was sticking open slightly. I was able to flush it with carb cleaner and seafoam triggering it with a 9v battery and that cured the problem.

I don't know it this is your issue, but it does sound similar.

(I also moved your thread to tech)
 

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Discussion Starter #3
Welcome.

I'm assuming that you have also swapped ignition coils to eliminate them as a problem?

I had a similar issue with my K6 750. The bike would start and run fine but when going back to idle, it would be on three cylinders. A few minutes later it would start up, run fine, repeat. It turned out the injector on one cylinder was sticking open slightly. I was able to flush it with carb cleaner and seafoam triggering it with a 9v battery and that cured the problem.

I don't know it this is your issue, but it does sound similar.

(I also moved your thread to tech)
Welcome.

I'm assuming that you have also swapped ignition coils to eliminate them as a problem?

I had a similar issue with my K6 750. The bike would start and run fine but when going back to idle, it would be on three cylinders. A few minutes later it would start up, run fine, repeat. It turned out the injector on one cylinder was sticking open slightly. I was able to flush it with carb cleaner and seafoam triggering it with a 9v battery and that cured the problem.

I don't know it this is your issue, but it does sound similar.

(I also moved your thread to tech)
I will definitely check that out! And thank you, brand new to this forum so I'm still unfamiliar with every section
 

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I will definitely check that out! And thank you, brand new to this forum so I'm still unfamiliar with every section
How did you determine it was cylinder #4? Just by the sparkplug? The header?
 

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Yes. I unplugged the coilpacks one by one to see if the idle was effected. Also after riding it I took the spark plug out and saw that it was wet and didn't show much sign of normal wear
 

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Yes. I unplugged the coilpacks one by one to see if the idle was effected. Also after riding it I took the spark plug out and saw that it was wet and didn't show much sign of normal wear
Nice. An easier way is to spray some water on each of the headers and see how quickly it boils off. I use LPS or WD40 sometimes but people worry about it catching fire. It's never happened to me, on a hot header it smokes off immediately,on a cooler one, it just smokes a bit.
 
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Nice. An easier way is to spray some water on each of the headers and see how quickly it boils off. I use LPS or WD40 sometimes but people worry about it catching fire. It's never happened to me, on a hot header it smokes off immediately,on a cooler one, it just smokes a bit.
 

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You could try swapping the injectors between cylinders. A minor gamble would be to swap the primary and secondary on the #4 as it sounds like the primary is stuck. Assuming that's what the problem is, you really ought to clean them all. Beware, the fuel rail mounting screws like to stick in the throttle body making them hard to remove. Any evidence of rust in the tank?
 
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