Help, my bike just died

[GZ250]

I was riding home today from town and while zooming along at 90kph I heard a LOUD clunk sound come from the engine for a fraction of a second.
I pulled off at the next off ramp and had a look.
Couldn't see anything wrong though, so I crawled it home and it seemed fine.
Took it for another ride to the dairy for a bus ticket just in case it got worse, then couldn't start it when I went to ride home from the shop.
The starter wouldn't turn, so I figured it was stuffed and that was the sound I heard on the motorway (it packing in).
I push started it and it ran fine and started to ride home.. 200m down the road and all hell breaks loose, the bike makes a hell of a racket and the engine dies instantly.
After getting it home (its a long way to push it) I took the starter off and noticed that some of the ring-gear/teeth had been smashed off the gear
This is on the engine gear, not on the starter motor gear.

Long story short, is it fixable or is the bike a goner?
Its a GZ250 (same as a GN250)

[bogan]

before you go about fixing it (gn motor so plenty of parts round i would imagine) check the extent of the damage, bits of gear may have damaged other components like the oil pump or gearbox etc...

but before you even check that, see if there is a cheep motor around, you may just be able to drop a second hand one in for far less than the cost of fixing yours

[gatch]

before you go about fixing it (gn motor so plenty of parts round i would imagine) check the extent of the damage, bits of gear may have damaged other components like the oil pump or gearbox etc...

but before you even check that, see if there is a cheep motor around, you may just be able to drop a second hand one in for far less than the cost of fixing yours

+1 You need to check what else may have been damaged. Little pieces of metal moving at high speeds can get into some pretty tricky places..

A donor engine may be worth investigating..