i have a Polaris sportsman 570, 2015. Stalled on wife the other day. Got it home and running. Lots of smoke coming out of exhaust and air filter box. Strange noise coming from engine where piston is, not a knock, but almost like a slapping noise. Any ideas? Smells of burnt oil

 

Possibly a burnt piston, pull the plug and get a small light inside to look it over, might also run a compression check, sounds like it might be time for a rebuild...how many miles/hours on it?

 

"Stalled on wife the other day"

I think you will find it seized on wife the other day. As Kymco wrote, time for a rebuild.