My friend borowed my Wolverine and left the choke half on for a few hours of hard riding. Would this have cause any damage to my motor?

 

No, it just wouldn't run as great as without using choke for half an hour of riding.

I've seen people run with choke on a lot without any damage.

 

What kind of damage could happen?

 

the only thing is that the bike will run rich and it could eventually do damage. I would not be too concerned if it was only a few time. Look at your spark plug if you are concerned about it. Replace it if it is black or clean it. I would not sweat the small stuff your bike should be fine. When I ride through alot of water I will ride around for a little while, if the bike is running rough, with the choke on