Good choice  
 
Plenty info here to let you know what your in for but I have to point out 
Problems occur from lack of maintenance or abuse
The bike doesn't have a particular "factory" problem unless you count the hot start issues some get from time to time.
Blown head gasket is another common failing but suspect that is down to poor service otherwise there would be a wanted section for heads for the racers here as they would surely be the first to wreck this fault !
Don't heavily use mine but had no probs with it over the past two years, it sits for weeks and fires up and goes  

  From time to time get the hot start problem - not that it doesn't start its just a bitch to start.
Hi-Octane fuel seems the best , well at least in mine  
 
There are a few in the for sale section - my first recommendation is look for one from a seller who has been on the site for a while and read all their posts, your going to find out about the bikes history that way.
Go in blind to a sale and expect the worse , that way you aint going to be disapointed when it all goes pear shaped  
 
Best of luck,
MM!