Recently bought this GS1150 with a grenaded motor for parts. PO thought a piston had melted, but I opened it up to find this.
Oil rings completely gone and both compression rings still there. The liner is badly gouged and looks to have lost quite a bit of metal.
Im not really having much luck getting a decent answer to what happened.
Other pistons do not have much carbon , so Im thinking the high compression pistons do not have much run time on them and the oil rings failed and caused this. Maybe the ring spreader was installed with ends overlapping?
On a side note, this shows just how strong forged pistons really are. That thing has taken a beating and is still in one piece.
Oh no! You will have to go big bore, 1230cc(?) now.
ive had oil rings break in 4 strokes, never does that. that was either too tight a clearance creating head, or ran super hot from airleak or something else. I would think the oil rings being destroyed or gone was a consequence, not a cause.