my friend was driving down the freeway on fifth gear, he was going to down shift to 4th but he miss and whent to 2nd, from what i know is car dies when he starts it, and i think he is only running on one cylinder. what is worst that could happen.

 

Worst? Well, from your description, it sounds like the worst DID happen. Best case, you shut the car off quickly and your valves just get a little loose. Do a valve adjustment and you're good to go. Slightly worse and you'll get some valve damage (bends, breaks, etc). Worse than that and the shock to the valvetrain/block could do lots of things. Timing could have skipped, and there would have been serious piston to head/valve contact.

 

from what he told me the timing did not skipped, and this is on a 2000 gsr it rev up to 9krpm and he still manage to drive it home after that.

 

bump

 

Pull the head off and take a look.