R3 cuts out under 80-95% throttle

Prob electrical/ground issue. I would swap out the wiring harness (with relays). With all the effort you have put into it, swap out the harness.

 

@Martin Lewis did you ever figure this out?

 

Nope. I just learned to ride around it. Someone I talked to last month absolutely swears that the problem is the quick-turn throttle, but that's silly. I'm like %80 sure it's the chinese exhaust and the fact that I haven't put a tune on it.

 

I didn't see you mention that you tried this specifically, but it's worth a mention.
I saw you have a 3rd party (non-ecu based) quick shifter. I've met at least 3 people that have had wild, weird symptoms very similar to yours that all stemmed from these quick shifters.

Have you tried removing the quick shifter crap all together and riding it?

side note, I had similar symptoms as what you mentioned in your first post and ended up trying new coil-packs despite the coil packs in the bike bench testing good. New coil packs solved the issue. I also had similar symptoms again that resulted in clogged injectors.

But maybe remove or completely disconnect the quick shifter and see if anything changes.

 

When power cuts on and off really quickly, issues lean more towards an electrical issue. If the cut off is soft fuel! Bypassing the shifter is where I would start

But from your video of the bike ideling it does seem like its got a big vacuum leak, maybe when you replace the throttle bodies you didnt seat the rubber grommet all the way around. I would shine a light and verify the throttle bodies are seated and no rips are in the rubber boots that hold the throttle.

 

I would remove any aftermarket parts including the aftermarket quick turn throttle. That will take any outside factor out of the equation.

 

This is all about engine braking, YCCT or ISC doesn't matter.

Side stand up and in gear and clutch out. ECU thinks you are decelerating (at lower throttle angles). Throttle plates open, or the ISC valve opens = less engine vacuum and less engine braking = less wheel hop. This is a good thing.

Side stand down or clutch in, or in N, idle normally.

This all works great until people start removing stuff because its "not needed" for a race bike. Then they have wonderful issues that they can't wrap their heads around.

 

I had an issue with my old bike that would cut for a half of a quarter second but only at lean. A fresh tune fixed the issue.

 

I think I may have figured out my issue.

I tried a fresh ECU with a new flash and ditched all the aRacer stuff and quickshifter. Issue was still present. The bike stumbles hard at WOT at high RPM, does not start well, and dies at idle when rolling into the pits.

Ordered a used fuel pump assembly and when I pulled the old assembly I noticed the fuel filter looked black... I suspect this may have been the issue. I have linked pics below of old vs new (used) assemblies:
https://imgur.com/a/6ks0alq

Need to get it back out to the track but I am thinking (fingers crossed!) that this was it.

 

Alright guys I found my issue.

I proceeded to replace the entire fuel system (pump, lines, rail, injectors) and the issues still persisted. I bought a compression tester and cylinder #2 measured 125psi while cylinder #1 measured 75psi... Looks like I am looking for a new motor.

 

Today I learned, R3s are twins...