paul g wrote:So when you say the ring land "closes up" is that actually the worn piston surface burring over the ring gaps?

And .. why is the diagram pointing to the top outer diameter of the piston crown which isnt related to where the ring sits ...

Sorry for being thick here, i really do want to learn about my Rs and the finer details of keeping 2T's going ... I really need to as i am riding mine a lot.