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With regard to ported pistons, the ports bases are 5/8 inch up from the piston skirt on Scott pistons which are 2 15/16 inch high plus deflector. The port tops are 1 15/32 inch up from the piston skirt, making the ports 27/32 inch high.
Each port is 13/16 wide with a 3/16 bridge beween to match the transfer port bridge and the ports of course in line cetrally with the transfer ports. The ports have 1/4 inch radius corners, and the cut out in the cylinder skirts clears the ports at B.D.C. At T.D.C. the ports are still open about 1/16 inch into the transfer ports. I made up a pattern out of thin brass sheet to mark the ports. This mod as well as improving the breathing, keeps the piston crowns cooler and improves the lubrication of the little ends. Hope this is of some help,