This is what happens when an AR125 exhaust is too restrictive and holds heat on the front of the piston...
Starve a CR250 of fuel and this is what happens (another weak fuel pump/regulator problem).
What happens to a CR250 piston if the bore becomes worn and a ring get caught down a port...
What happens to a CR250 piston if the bore is worn and the piston can rattle. You can just see the hairline crack on the back of the piston (inlet side). Caught it just in time...
What detonation can do to a CR250 piston. Here, the cylinder head squish band was incorrect allowing detonation to occure which allowed the top edge of the piston to be erroded away.
What a weak fuel pump can do to a CR250 piston...
Mostly YZ125 pistons that had mechanical alignment problems with the barrel. A reason why air cooling can be a bad thing...
When you overbore a YZ125 and part of the cast iron barrel liner breaks off, this is the result...
