I've seen that happen to axle shafts with big tires and lockers involved.....never on a crank!! What could have held that flywheel so tight that that could happen??!?!?!
Looks to me as a fail in the process of builiding it (Yamaha Factories). Thats the thing I dont like about Yamaha, they kinda half-a$$ed 2002-2006 blasters. But I love love love their bikes