i put 50,000 miles on my 07 Yamaha Majesty (in a couple years) and the only things that ever went wrong were (i believe) my fault and not the bike...
Water pump seal failed at about 25,000 miles because the coolant had never been changed in 12 years...Clutch shoes wore out at about 40,000 because i never changed/cleaned the clutch air filter...Regulator/rectifier took a crap because i was using my scooter to jump my sisters car during the ice storm we had last year and had the car and the bike running when i did...
i think thats it
OH and the stator went bad...really not sure why that one failed...might have also been from improper jumps. I never knew you shouldnt have the car running when you jump a bike...
None of those repairs were very expensive at all. I think the stator was the most expensive. Couple hundred bucks
Im not counting the clutch though because i installed a malossi and some dr pulley sliders so im calling it an upgrade as much as a repair cost
I guess my steering head bearings went bad too...developed an indent. Didnt really need fixed, it was just annoying. That was only like $30 for all balls bearings replacement. (SUPER pain in the arse to do though...i was glad to be done with that). But im also not blaming the bike for that one...i hit a LOT of bumps
In summation...if you arent afraid to throw a wrench at them...seems like they can keep going about forever without swallowing up TOO much money