help with piston failure

[shakenbake]

guys i need some help with this failure. this happened last winter, just getting around to fixing it now. the pistons are from a 2012 polaris 800 SB assault with 1800 miles on it. the piston that failed was the Mag side, the other piston is from the PTO side obviously. here are the events that led up to the failure. sled ran flawless until the failure. the sled was warmed up to 125 degrees, like it has before every run. sled went for 1.5K and died. pulled rope fire up again went for 100 ft died and is now locked up. towed back to trailer and loaded back up. now when taken apart on saturday was expecting to find both pistons screwed up. we were assuming a cold sieze, and were are little puzzled when we pulled the pot off to find one piston severly scored and the other piston normal. i did not get a chance to takes pics of the pot, but it was not pretty from what i was told. looking for opinions. the plan now is to pull the engine and go thru everything and start from the ground up. thanks for your help!!

 

[turbolover]

Contact the guys at PMS in Ashton, ID. They are a MTNTK Fix kit dealer and can hook you up with better pistons and the spacer plate.

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[sled_guy]

From my experience that is not the sort of normal scuffed piston failure so many of us have seen. It looks like you might have an injector issue or something on that cylinder. Would be worth having the injectors cleaned and checked.

sled_guy

 

[shakenbake]

sled guy i 100 % agree this is not normal. that why we are stumped. yes injector will be tested for sure. what do you think possible crank seal leakage and leaned that side out. like i said in the original post we were expecting to see both pistons scored. when the pot came of we said WTF.

 

[sled_guy]

I'm not going to say it wouldn't be a crank seal, but I have rarely seen that. Usually the seal failures I have seen have manifest with an oily mess being blown out the seal.

But at this point you'll want to inspect everything.

The 2012 and newer injectors have been pretty solid from my experience, but that is where I would look first.

sled_guy

 

[shakenbake]

sled guy thanks for your input, i will post our findings when we get them. once again Thanks

 

[Leftys]

That looks like a lubrication issue. Please show pics of Piston crowns on both MAG and PTO pistons. Did you clean the PTO piston. It looks very dry, no oil residue at all.