Those cracks look like from vibration. Any abnormal vibration that could have caused them, crank out of balance, something in drive-train? Maybe the vibration caused your engine to shake so much that it damaged your pistons. Your plugs look good, I would agree it doesn't appear to be a lean condition. Is your dealer going to check the lower end and crank. Maybe out of balance crank. I had a 4 wheeler that ripped a steel frame to pieces and cracked the cylinder due to a out of balance crank. It also took out the piston because of vibration. Just I thought I had when reading through your post.
Keep us posted what you find and how things turn out.
Very good thoughts. No noticeable vibration at all. Not more than stock anyway. I wanted them to pull the bottom end apart but they didn't really want to do it unless I was paying for the time. Cause if they pulled it apart, and it all checked out, Polaris wouldn't be paying for the labor. So I said screw it put it together.
Just picked up the sled this evening. Rode away from the dealer and cranked on about 10 miles. Right off the bat it was over revving to around 8500, and didn't seem to be pulling hard at all. But that cleared up after a bit and it's running mint right now. Works really really good.
Got a foot of snow dumped on us last two days for a total of close to 2.5 feet of snow. So I got to test all my Mods.
My intake seems WAY better than stock for snow ingestion. Nice and sealed, so no snow ingestion, not to mention I can't believe how this thing doesn't want to bog down in over the hood powder. With the stock intake it would have been running out of air a long time ago, where as now it ran awesome when under snow. Only got one small dead spot from lack of air. So pretty impressed with that. It's dark so I didn't do any plug checks to see how the plugs looks at WOT. But it's also I new motor. Maybe best to wait a bit.
Skis, So far I say junk. I don't like them. Don't side-hill worth beans, and the tips are to narrow, they don't climb onto drifts of snow piles well. They stab in and make the belly pan do the lifting on the sled to get up on top. Steering effort with the stage three fins is quite hard. WAY harder than the stock grippers. So far, I wouldn't recommend these skis.
Lights. Very good light. But I didn't have the light covers installed that some with the lights, and those are needed. IN any kind of powder the light packs full of snow, the lens is warm, so it sticks, and freezes. Then your stuck with as good as no light. No the provided rubberish light covers are most definitely needed.
Running boards. Well. There are not enough good works in the english vocabulary to describe these boards. They are simply AMAZING. No snow, EVER. There is always positive traction available no matter what.
The track could hook up better in this baseless snow, but what track couldn't? It did fine, but not super awesome in really dry light powder. Once it found an old track or a bit of base of sorts, it hooked up amazingly. Lots of traction there. It is noticeably louder in the tunnel though than the stock track. You get some track noise, as well as what seems like a small vibration. Nothing serious. But something to get used to.
Rear suspension feels like a whole new skid with the heavier rear springs and fasxtrax valving. Very very impressed
Front end being narrowed up, with no sway bar, and some roll in the shocks is very very tippy. Slow turn on soft snow are tuff to do with out carving. And I can tell it would be horrible on the trail. But it's amazingly flick-able. Very agile. I can tell it would be a killer boondocking setup.
Over all I really love how this thing turned out. It's just really disappointing that it doesn't want to keep the engine together for me. So I'm still selling it. But It'll be hard to see it go no doubt.