My dad and I jsut left Lake Gogebic. This is a trip to remember. We killed 5 rev skidoos but none going at high rpm. FOur of the five burned a mag piston at 60 mph range. The dead: a 2007 ss500 rental(as ran out of perosnal rides). The dealer showed us the psiton ant scored on four sides and said cold siezed. My dad is 35 years of riding and an ex skidoo dealer, and rode 10 minutes before wfo at varying speeds. PS temp was 17-20 degrees for all of these. A new gsx 2007 with same issue, after 15 miles of a lake run, a 5 minute stop and 8 miles of 60 mph range. Then a 2006 Mach z 1000 x with 700 miles, same thing 60 ish halfway accross the lake. Lastly, his Bikeman 1100 renegade on a trail at 60 ish, mag piston. My 05 mach z, after doing a chuckroo kit all bolt on ran awesome and 112 radar with 280# rider in terrible snow conditions. Had a vibration like track or belt and shut it down, then never start again, and no spark on either plug but good compression. OK the question: all of the 4 burned at 60 mph +/- 5 mph, all mag piston, all plugs nice brown color at 17-20 degrees. makes no sense. Is there a lean spot? If so wouldn't there be white plugs? Is their a lack of oil spot, like where variable oil mix is too low and has not upped the mix yet? Or ?????? Baffled as all sleds perfectly indoor heated stored, fresh 93 octane, properly driven and warmed, and plugs looked good, only bmp full synthetic oil used. ANY HELP OR IDEAS??????