, why don't you go pay some guy 60 grand for his z28 and make him really happyif you buy the xrs make sure the crank cases are not the stock ones as the problem with 07 skidoo 800 motors was that the crank cases were out of spec, so when the crank is heating up from running the motor the crank will expand and there is not enough clearence in the stock crank cases causing the crank to seize. Just saying it happened on my 07, and alot of other 07's as well, i ended up getting a reman 08 motor and problem solved
....Bearing clearance was the issue due to the difference in the HO (2006) to the 800R (2007+). No one sled is immune from what I have seen and pulled apart, no matter what time of year it was built. Seems to be more related to the sled itself, combination of parts and operation/warm up. XRS, X, Adrenaline, etc. The clearance issue was (suspected) due to the water cooled bottom ends on the 2007's, the case expands and preloads the bearing when the water temps were too cold or fluctuated with hot and cold coolant flowing into the motor. Once the break-in is over, the fuel leaned out and the parts got hotter. Lots of these engines failed quick and within a few miles of the trailer, others maybe got lucky until the ISOFLEX ran out, the bearing wore more and got hotter, then spun in the race. Some engines were fine and never had issues. I've had lots of speculation as to why...my theory is that the ones that lasted were probably warmed up better than others on occasion.
well, this is all just speculation but
There was discussion around mineral oil being better for the 07, as it broke down and allowed the bearings to wear a little more, thus increasing the bearing tolerance and thereby decreasing the preload. Crank run out was an absolute must to check when buying these sleds. Sellers may not know that it is out of spec and may not be misrepresenting the sale, its just a fact of life with these engines.
The supporting info for this is that in 2008, the bearing clearance was increased (0.0002"), the synthetic oil was spec'd to accomodate that larger clearance and minimize wear now that the bearing clearance was larger, and the 2008 R's also had a thermostat to control the temperature. IMO the best thing you can do for a 2007 R is install the 2008 T-stat, always let it warm up well and run mineral oil in it. If you've got some miles on the sled then its probably fine and not too much worry, as its been heat cycled, now you just gotta watch the ISO and re-grease as necessary.
