Cal and Billy, Cory Hogan ran 255 against Larry back in 2009 at Valdosta, they both recorded 225 at half track.
I'm not saying 255mph is not possible but a Nitro V twin recently ran a ridiculous speed at the stripe.
When they slowed the video footage down at the line, it was proved that the front wheel touched down as it came off the bars just after the first beam, shortening the speed trap length by the wheelbase of the bike.
Still awesome speeds though in any ones books.