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Discussion Starter #1 (Edited)
Hellooooooooooooo!.....

Alrighty, so Hi. I'm a newer member who's been buzzing around in the background surfing through search engines while essentially rebuilding my gsxr.
From anyone who's seen my original intro post and remembers the green gsxr with kawi stickers painted on ahahha.. Yeah that's her.

SO as for the problem.
The bike rides SMOOTH.. So smooth it's like, well I wont get into it. Bike doesn't hesitate, jump, irk or derk. However the minute she passes 7-8k rpm she poofs out a bunch of black smoke.
NO OTHER TIME will she run black smoke or anything, not until high rpm.

Bike has had done:
New spark plugs
Danmoto slip on <-- Yes i know i have brand new ixils coming tomorrow.
K&N Filter
Rebuilt and cleaned up the fuel pump and filter + a new tank.
Just put on a brand new fuel line.
Ensured all air hoses are where they belong and nothing is unplugged.
The electrical system is fine, FI is fine, put in dealer mode and -C00 is showing all clear.
No pwr cmdr.

What on earth am I missing, and how worried should I be??

Thanks!!!!

Link of me going brap at a gas station. - Warning: Turn down the volume lol
 

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I know things... A lot of things.
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3,149 Posts
Have you considered the possibility, that the engine might be running with a bad AFR overall, depositing soot in the exhaust manifolds, which only gets blown out at higher rpms when enough pressure develops in the exhaust? I'm leaning towards that explanation because:

  • You do seem to have enough mods to warrant a suboptimal AFR.
  • The K4 doesn't have secondary injectors, or anything else that might cause a sudden fueling change after a given engine speed threshold (as far as I know, with the possible exception of a fueling strategy shift from IAP-based to TPS-based).
  • Even if something does go bad after 7-8k rpms, I'd imagine it would have to be pretty bad to produce soot at a high enough rate, to blow puffs of it out of the exhaust, without the soot pre-existing in there. I would think you would notice it when accelerating past 7-8k rpm in gear. Do you?
 

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Discussion Starter #3
Have you considered the possibility, that the engine might be running with a bad AFR overall, depositing soot in the exhaust manifolds, which only gets blown out at higher rpms when enough pressure develops in the exhaust? I'm leaning towards that explanation because:

  • You do seem to have enough mods to warrant a suboptimal AFR.
  • The K4 doesn't have secondary injectors, or anything else that might cause a sudden fueling change after a given engine speed threshold (as far as I know, with the possible exception of a fueling strategy shift from IAP-based to TPS-based).
  • Even if something does go bad after 7-8k rpms, I'd imagine it would have to be pretty bad to produce soot at a high enough rate, to blow puffs of it out of the exhaust, without the soot pre-existing in there. I would think you would notice it when accelerating past 7-8k rpm in gear. Do you?
Hey, sorry I've been offline for a week or so.
I do have a few mods, and I somewhat figured that maybe the afr was off. I was thinking about picking up a Pwr cmdr locally or just tuning it... But I don't notice any smoke while going 1-6k, and my buddies riding behind me don't notice any smoke going 8k+ it's either in neutral there's smoke briefly or right as I crack it on going wot for a moment.
:gaah lol
 

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I know things... A lot of things.
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Does it blow smoke even if you gently accelerate to 6-8k, using only as much throttle as necessary to raise the engine speed relatively smoothly? If my theory is correct, engine speed would not be the only deciding factor. Perhaps more important is throttle, as it directly relates to pulse pressure inside the exhaust. When you blip the throttle to raise the engine speed, as you do in the video, you create short high pressure pulses in the exhaust, that might be better at evacuating any collected soot in there, than coasting at 6-8k in gear. (Also, when riding around at high speed, it might be more difficult to spot the smoke plumes.)
 

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Discussion Starter #5
I can't recall immediately, my lunch is coming up at 4mins from work.
I'll run out and make some noise in the parking garage :D... Then take it for a spin lol.
 

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Captain Obvious ... because obviously it’s obvious
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I'd check the fuel flow and the fuel pressure.
 

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You should listen to me. No, seriously, listen to
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"possible exception of a fueling strategy shift from IAP-based to TPS-based"

I wonder if his TPS could be bad. It might be worth checking out. First check that the TPS is properly adjusted per 4-18 of the service manual. Then disconnect the TPS and see if the sensor resistance varies smoothly as the throttle rotates. See 4-34 of the service manual but beware that step 4 may have an error. You should be checking the pins that connect to the P/B and B/Br leads, which I think are the outermost pins. Also check between the leads to the P/B and R leads, which I think are the top two leads. What I'm wondering about is if there's a sudden jump in resistance around mid-range as the throttle opens.

"Ensured all air hoses are where they belong and nothing is unplugged."

You might as well check again that the hose and electrical connector to the intake air pressure sensor are OK. Note also the PAIR control valve hose that runs from the throttle body to the control valve.
 
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