RE: So, what about this new 60 in a 40 size Evolution?
The only example of an overbored engine I tried was the ST .90. It was a real shaker!
At some point in the design, the load of the heavier piston becomes a challenge for the rod and crank to support. The lower end can only grow to a certain point before backplate only mounting is doable. I would guess that this engine has had more attention paid to making the piston light than usual? If not, it should.