Originally Posted by mgorman
Looks like a combo deal, not enough oil & gas. The mechanicals are an oil deficiency but the holed piston is usually caused by a lean condition. 1st thumper I've seen hole a piston, I usually see 2 strokes doing that.
I haven't had 4-strokes bikes long enough to know for sure, but I don't think that was a lean burn through. It doesn't look melted, it looks like something hit it.