Any ideas on my 425hp Gen II current issue?


I have a K11 that I've had back from my builder for a short period of time. I was at the shop for the last day of tuning and I was present at the 425hp pull. The ending pulled strong and didn't seem to have any issues (although it did smoke which my builder said was not abnormal and it cleared up pretty fast)

Anyway, I ordered new plastics for it so the bike has set for 3 weeks or so when I redid the wiring on my dash gauges and waited on my plastic.

Fast forward to last night. I took the bike out and made a couple of pulls. It developed a 'stumble' that came on right at 6 grand under full throttle (it reves just fine). I figured I had a pinched fuel line, so I spent hours trying to figure out the issue with no luck. Although the stumble how now moved further up the RPM range and starts about 7K

My fuel pressure and A/F gauges show no issue at all. The charge temperature of my air to water is in the low 90's.

I'm just lost.

I've uploaded to video's, one is just the sound of the bike (phone was in my pocket) and you can clearly hear the stumble. Second one is the arrangement of the undertank.

Any help is greatly appreciated. Wife and kids are gone all weekend and I figured I'd put some miles on the bike . . .
Are you saying your inlet temps at 425hp are in the low 90 degree F.
If so what ever you are using to measure the temps is calibrated incorrectly, or not working at all, or if someone told you those temps they lied. Even running an ice tank you would be very hard pressed to get the temps down that low.
I have a pretty good idea what is up with your bike, but seeing as your builder knows more then myself and most others (self proclaimed) I will leave it to yourself and your builder to work out the issue.

I have a temperature probe in the water to air at the back of the box. It feeds to a digital gauge when I took the bike out that gauge read 90 degrees. Keep in mind I couldn't get the bike above 6K rpm. I've seen it as high as 110 if I let the bike set, but once it get moving it cools down pretty quickly.

Richard, I'm not interested in any type of conflict with you, good-natured or otherwise. I'm simply on here looking for a answer to a problem on my hayabusa, the bike that brings us together.

An update, I found a boost line that went to cylinder #3 was off. I got it back assembled and took a short trip up the road. Full throttle was fine up until 8K where the stutter came back.

Richard, may I ask - as myself, not my builder - would you please share your thoughts on this?
does he have check valves inline so map sensor doesn't see boost?

where is af chart from dyno?
You'll have to forgive me here, but we have a gm 3 bar that has a boost line right to it. There isn't a check valve that I'm aware of.
Changed your plugs lately ?

Yep. After the last dyno session. They have less than 100 miles on them. I also checked to make sure the caps were on tight.

It really is odd. Bike runs great and very smooth - until the 'stutter' kicks in. I find it interesting that I'm 'chasing' it up the rpm range. Started at 6, checking for kinked hoses got it to 7K, and the boost line got me to 8K.
Craash, my 05 turbo did that same thing, except it wouldn't make any boost at all. I swapped out the 4 secondary injectors and the problem went away (stock injectors).
I have new 44lb injectors in mine and it's making boost now - things are starting to get violent by 8K. They 425 pull was maybe 4 weeks ago. I have less than 100 miles on it since then.

Im missing something silly, I hope. Maybe Richard will share his thoughts with me so I'm not just spinning my wheels here.
To be fair here, the last day at the builder the bike was screaming. I did redo the digital gauge harness so it's likely I hosed something. Just can't figure out what it might be.