I got a vmax 600 last spring, hadn't been used in 3 years, sat outside on a trailer, but he started it every year. We did a very light lookover, new plugs, cleaned airbox, seafoam, new crankcase oil. Ran it this year on the 2x no issues. Ended up cleaning the carbs because a screw came loose and only one flap was working. I put about 160 miles on it this season and today it seized up. The pullcord won't budge and my right cylinder spark plug is gray with light gray specs. I was full on oil. What could have caused this? I didn't see my overheat light come on and there was plenty of snow and coolant. any tips would be appreciated on how do begin finding the cause and if its worth rebuilding or just parting out/ junking.