Originally Posted by boozewz
Really appreciate the comments and help fellas.
Dust entry is a major possibilty as I'm based in Saudi and all our riding is in the desert.
I just inspected the pistons, and lo and behold, there is a crack on the bottom side.
Could the impact from the piston scoring the liner be such that it would cause the piston head to crack? That seems like a serious failure, regardless of the dust entry or not.
Google "yzf450 sucking sand through breather hose". It's a well known issue with those bikes. If you are high centered/stuck on a sand dune or in deep water it sucks stuff up through the hose into the engine.