@Celica -
The interior on the cylinder wall is slightly larger (1.5mm), the outside diameter is MUCH larger, 22mmx20mm. I will be the first to admit that I don't know too much about porting cylinders, it's why I sent it out to have it done, see what he did and then see how it preformed compared to from factory. What would you have done?
@CuperJusto -
How much weight did you take off the clutch, 2 or 3 shoe?
What did you do to the piston? Photos?