I remember a company that used a thick abrasive hydraulic paste and would force/pump through high performance 2 stroke cylinders to identify high friction areas and it would also clean/smooth up the ports, it wasn't necessarily used to "port" as much as it was to identify where attention was needed in porting. twocents popcorn
Copper

Common sense, the least common of all the senses.
Mom.

For fear of ridicule, society stifles creativity.
Ricky Valdes