It’s a two-stroke, actually. Still on original piston and rings from 1984. Few tens of hours, probably. Cast piston skirt might start to crack around 200 hours; so 200k — definitely not.
Man, you sound like me, ride antiques. Putting a piston in an old smoker is so easy compared to the new 4 strokes.
I ride and old YZ490, an IT200 and a RD400. Getting parts is getting tough though. Ebay is my best friend.
Oh, forgot, put a CR250R water cooled smoker on a shifter cart. That is a really bad boy there. Accelerates so hard ya better have some neck muscles to hold yer head up.