I'm quite sure that these pics are from Chris Hoffmann ( Dasboata - the prop guy ). He did not show pics of the piston for this cyld. I believe that's the only pic that Chris offered. If ported this way for a rear exh. cyld., the piston and cyld. would not last very long. On a RE configuration, the power thrust of the piston skirt is supported by only that tiny transfer bridge. The half "sleeve" should be left in there for RE engs. Daniel Place ports the K30 with leaving the sleeve in there, so you RE guys might want to talk to him. The fitting in the transfer wall is for an external pulse to the carb.