My 05 Busa has popped out of gear twice now.
once while decelerating hard in 1st, it popped to neutral.
another time, while accelerating hard in 1st, i shifted into 2nd, started accelerating for a second or two and it popped into neutral.
spoke to my mechanic, and he thinks i might just be shifting poorly, as it doesn't happen consistently...
...just have 400km on the bike. i'm just breaking it in.