@rraleks
Who says it’s running lean? Overheating is caused by different things, lean is one possibility only. Check your radiator coolant level please mate...
No way the crank has a 5.5mm longer throw! It’d of locked solid against the head...
Please check your radiator coolant level!...
I ran my bike well lean for 1000’s of miles without damaging the piston. It was only when my head gasket blew and emptied my radiator that it ran it hot enough to eat the piston, in the same way as yours...