Well I watch superbike, supersport and GP races on TV, and the speeds they quote are very seldom close to 200mph on the straights...
Of course, if you're talking about a track like LeMans, with a huge straight (Les Hunaudières), then it's different, but on most tracks, the super high performance bikes will reach 250kph, not much more...
I do know about the Transports Canada Oval, actually that'S where Moto Journal/Cycle Canada made their Hayabusa/Kawasaki top speed test... But I'm pretty sure it's not open to the public.
So going over 300kph will definitely not happen to anyone, and those rare people who will will certainly find a way to remove the cutoff...
Cheers,
-Seb