2012 crank/clutch/cyl skirt failure

[Shitfly]

The 2012 was running fine last/first season on it for me, minus a primary spring broke. Only change from stock was a can and 13.1-1 PAR head, no issues. This last summer was at 1500 or so miles, decided to do the top end fix kit with head shim. Took it out around home last month once some snow was around, broke it in nice with lots of oil in tank etc, but had to add a gal of race gas per tank, hit the DET riding at home elevation, 3000'. Went for a ride south of Revy and put on another 60-70 miles and was running fine, never tagged the DET, temps low and steady around 130f , then growl-stop while on the trail...no warning, lights etc. Thought maybe top end, but after pulling top end off, found a cracked Cyl skirt and crank seized..damage on the pto side obviously, went to pull off primary clutch and it broke in half on the shaft, inner sheave was super stuck of end of crank, lots of fun. Any ideas what caused what?? Bad crank bearing heated up clutch and caused piston slop in Cyl? Or bad clutch, caused crank to overheat/rev, cracking Cyl skirt? Engine Torq/flex stops? Haven't heard too many issues about the cranks on the pros..and can't say I've seen or heard of a clutch more or less just 'fall apart' with the slightest turn of a puller..

 

[chrishew]

Ouch Man. ****ty way to start the year. Definitely sucks after putting in a new top end as preventative maintenance. What brand fix kit did you install?

Don't know much about crank failures but judging from the pics looks like you may have had a fracture in that clutch for a bit (break line looks kind of dirty) Were you noticing any engine vibrations?

 

[adamg]

The primary cracking in half is a known issue on that year Polaris.

 

[Shitfly]

Not going to say what the top end kit was, not the issue there, and it ended up being the one thing other than the crankcases and head worth saving really, haha. Never heard or read about failures on the clutches like that, but I believe it now! Never noticed any vibrations prior to the quick stop on the trail either.. The dirty/rusty looking break could be from sitting in the shop for a week before touching it. Either way it'll be back up and running by Wed/Thurs, just thought I'd bring the subject up, too see what others had come across with some related issues! A pic of the inner sheave off the primary after removal.., haha. Fun job...