The timing chain idler needs to be watched... Lots of info on here, it isn't too bad to replace but does take a couple hours. Like every carb'ed yamaha, you can't have the carbs too clean! My nytro (same engine) managed to plug up its idle jet while out on a ride this year, have never had that happen on a sled before!
Also, the oil tank can develop leaks over time. I decided to be pro-active and drilled out the mounting holes and was going to mount it on rubber grommets. Apparently the torque from drilling it was enough to crack it, which wasn't visible until there was hot oil in it... (There are some REALLY nice welded aluminum tanks on ebay now, a little expensive but a nice product.)