the thing that causes the pop out issue is the shift forks (mainly 2nd and 6th) get bent and wont hold the gear in and then it pops out. is it safe to ride?? that is all about your defination of safe. if it was a cage that poped out of 2nd i would say sure drive it, but since it is a bike it could lock up and cause you to go down. wanting to ride is not worth the chance of hurting yourself or your bike. also there is metal to metal contact which is causing small metal shavings to come off and get into your oil which is not good at all for your motor either. its your call on riding it but i know i fix all issues before the bike is road worthy so that i wont go down for some stupid reason like transmission locking up going down the highway.