Sorry to hear it man,02 V Star 650 Classic. Took it in for some tires and other misc stuff. Dealer called. Spline shaft on Pinion gear gone bad. They say it's kind of crappy set up from Yamaha. Factory just gives it a squirt of grease and sends it on the way. No way to rebuild with out buying gear assembly. All gears need to match and you can't buy just matched set of gears. 18,000 plus miles on bike, not beaten on either. Bought it three years ago with 1329 miles on it. Called Yamaha about it. Got the old shrug off as it's out of warranty and no updates for it. Cost repair for a efficient, low maintenance shaft drive system as Yamaha calls it. So much for near maintenance free system.
Good rule of thumb is every time you change tires, take the drive unit off the bike and clean and lube those splines. Not difficult to do at all. Requires a particular type of grease, can't think of the name of it now.