Its funny with warranty.
You have Honda on one side of the road, where it is nearly impossible to get anything covered.
In the other side of the road, you have Ducati, who have so poor quality, and is a brand, where people often don't use the bikes much, that they have to use the "goodwill" as the bikes are older, but the defect is so common and unlikely to have happened by wear, that they pay out and replaces the part.
In the middle, you have Yamaha, who knows that you can't win without satisfied customers. There is too much hazzle over a part, that effectivly might cost $10 in production costs, than having an angry customer.
To my knowledge, Yamaha have always dealt with claims fast and fair.