I finally came down the straight and saw nobody in Sunset. I railed through the corner and hard on the gas. Upshift twice to 5th, dragged right knee into the Esses, the flipped it up, over the candy stripe, and hard on the gas, left knee down railing into the Mazda Gap at ~110 mph carrying my maximum lean angle.
All of the sudden the rear tire swung around. Holy sheeeeet. I'm getting a helicopter ride for sure. I roll lightly off the throttle and try to bring the bike upright. Gentle, slow moves. The bike straightens up. I have to get hard on the brakes now, so the rear is airborne and fishtailing around - but the bike is upright and in a line so I'm confident and bring it through the corner and onto the back straight.
Oh my god. I don't even bother getting on the gas, I'm just breathing. I plan to rotate around the track and go into the pits. I have a (virtual) load of crap to remove from my pants. woah.
Coming into the Bus Stop I notice my rear wheel sliding around. Did I completely frag the tire? Wow, I didn't think it was that bad. Maybe I should pull off here and wait for the session to end. Naw, they'll yell at me for being in an impact zone. I'll keep rotating around and bring it in. Bad choice.
I roll over the wheelie bump and into the Grapevine. At the first apex my rear wheel skids right, then left, then right then catches traction and *snap* I fly up into the air. The bike and I both tumble off the track.
The rear wheel was covered in fluid. Given that no oil was on my boot or in the belly pan, it was either the rear brake resevouir or a very weird engine problem that dumped fluid back but not down.
The "good news" was that I was rotating around at ~60mph when it happened. The first slide would have been much much worse.