I have a 2011 Switchback 600 with 409 miles on it! At 323 miles while the sled was still on warranty, it started fouling plugs The last set lasted 8 miles, started to bog and then run on one cylinder and changed the plugs and it was good! Seems when it warms up a bit, it runs poorly. had it to my polaris dealer and they just charge me $300 to tell me nothing showed up! If you let it warm up by idling to temp, needs new plugs, over fuels real bad. Had it out today and it's 0 degrees c, ran rough at idle , once you got over 2000 rpm smoothed out. ran over to neighbors and on way back started to bog, changed the plugs , ran good, when I backed it into the shop , it would backfire when I engaged the reverse, it was up to operating temp. Talked to the service manager at my local Polaris dealer in Lloydminster and he blamed it on the NGK plugs that they sold me, it fouls Champions as well. he did concede that I should maybe take it to the dealer in Vermilion or Bonnyville, having another dealer look at it might find the issue. Seems when it warms up, there is a problem and the sled over fuels. temp sensor? or just coincedence? First started last summer when I was fogging it. I could not get it to run and it overfuelled and ate plugs like candy! What do you think?