I'm working on one of my project skis (1992 VXR with the 650), rebuilt the carb, made it a pre-mix machine, checked compression (150 psi and 135 psi). I got it started, but notice a rattley sound at lower rpms, settles down at higher revs, but I dont know if I can say it's gone at the higher rpms, just not noticable (I've only started it for short bursts, until I can pull it out of my garage and hook it up to water). I have noticed when I stop the motor, it wil rattle 3-4 knocks for a second or two past the last fired cylinder. It definatley seems to be the motor (not the pump, and nothing vibrating against the fiberglass body). I'm hoping this is rining a bell to someone out here in this fourm, I don't want to pull the top end off if it's something trivial I haven't encountered yet (I'm not use to a yamaha motor that fails ) This ski has sat for some time, and I know when I pulled the fly wheel cover that there was corrosion on the flywheel. I've seen some threads stating a possible fuel issue, and I did use premix from late last season to start this one, but I don't think that's the reason here. Any ideas?