Dreaded Whirling Sound 2019 300rr

[xdab]

Know there's been volumes written and discussed re: main bearing issues but with all the content out there on the subject I still can't make sense of the following.....

Bike running fine with OI. Always had. No hint of any problems, failure or otherwise.
Decided to remove OI as preemptive measure and go premix. Moved as per discussions capping nipples and disconnecting wires. Straightforward.
Drained every molecule of straight gas out of tank before filling up with 50:1 premix (Castrol 927)
Rode for first time about 30 minutes before started to hear the whirling whiny sound. Sounded JUST LIKE some of the vids submitted.
Limped back to truck about 1/4 mile away and called it a day.
Once home, to rule out something coming from running gear, I put bike up on a stand and, with bike in neutral, started it and immediately noticed sound again. Not overwhelming but pronounced. Something definitely not right and of course I'm thinking it could be main bearing(s).
Just for grins I drained oil and saw nothing that would indicate trauma. However, I don't know how the stressed part of the bearings are oriented and if it were to shed anything where it would be deposited. So, the oil drain was basically just to get a box checked.
Scratched my head for 24 hours and decided to start it again. this time....no unusual sound at all. Cycled through the neighborhood several times waiting for it to sound off and nothing. Business as usual. Granted I didn't put much of a load on it but certainly didn't when I started it on a stand 24 hours earlier either when it was cold. Confused.

Question is what could conceivably cause the sound if not main bearings, why seemingly intermittent and how on earth could this coincide with OI removal? Is there something about the OI system that offers some sort of indirect lubrication to the bearings that switching to premix does not, at least the first bit that's run through? Again, I don't know how the bearings are oriented in there not sure what their source of lubrication is.

[Dr Z]

No other lubrication anywhere else with OI, just injected into the intake instead of already mixed in fuel. Mine was working great also, but I just don't want to always be worried about it like you. I would think it's not the bearings if the noise is gone, but still possible I guess. Not sure if there is any easy way to tell until they go or not???

[twowheels]

The sound starts out like an electric fan running, occasionally at first, then more persistent. The volume increases and the noise becomes a squeal. If you chose to ignore it it can get to the point where you're losing crispness on the bottom end (almost a sluggish throttle). If the cage breaks or the seal gets sucked in the effects are exaggerated.

[xdab]

OK. Good info. Not sure my issue rose to level of a squeal but definitely an unusual moaning sound. Puzzling thing is that I can't get it to duplicate. Guess I'll go ride it hard and be prepared to shut down if it does it again. What if it doesn't? What could it have been/be? You'd think that if it were a bearing failure it would reveal itself again and persist. Right????

[Hurky]

Hi xdab, did you ever find out the reason for this sound ?

Cheers !