Quote Originally Posted by CrappiePappy View Post
Something along these lines might have happened with the previous owner ....

Sir CrappiePappy is pointing out something I will not touch on the V-6 Yamaha engines. One engine(I think it is the 225HP) is not a Interference Engine (Valves will hit the Pistons when out of time) the rest the Valve timing has to be perfect. All the points must be perfect the first time. I think the 4 cylinders like Slabs has a single tensioner but the V-6 engines you have to line up several marks before putting the belt on. Since the Cam Pulley is a Variable Valve Timing Pulley they can fail causing a Run-Out problem with the belt alignment shaving the belt at first but over time damage it like the picture Sir CrappiePappy provided. Moral of the story if you run a Yamaha V-6 remove the Cowl periodically, remove the large black plastic cover over the Flywheel, and look for black dust accumulating around the two Camshaft Pulleys. You want to catch that failure in the beginning stages. The timing belt will crawl downward too, it rubs on the block when the Pulleys begin to fail.