The Royals Star engine is nothing like the Liner engine. But, there have been a very few early Liners with lifters collapsing while setting. They quiet down as soon as the oil pumps them back up. Yamaha repaired the ones I know of under warrenty. The charge I saw to Yamaha was just under $700.
I think Royalstars have a five year warrenty? I would talk to your dealer.