The two factory teams, Kawasaki and Honda, had widely differing views on making usable power. Which can be seen today in the two 500's.
Honda chose to reduce reciprocating mass and use cylinder porting and head shaping to deliver power. Kawasaki's factory bikes, in the US and Europe, increased reciprocating mass and lowered compression to do the same. Kedrowski's and Larroco's SR500's all had much heavier cranks than what ours are. With little changes to the cylinders original design.
You're never going to get your KX to run anything like Goebers non power valved, steel sleeved Honda. But you can add a thicker head gasket and flywheel weight to your KX and make it run similar to Kawasaki's factory machines.