I put a 230RC 2 bolt cylinder on an ole G23 case..Takes a little hole tweaking but it will work....The transfer ports need a little matching also, on the base.....Worked OK otherwise..[8D]..Somewhere along the like Zenaoh made a 23cc cylinder that had the same wide transfer ports as the G26..I have one of the cylinders, same dimesnsions and even the same casting number, 2075, but a 32mm bore....A 26 piston is too big, but with a 23 piston is runs just like a 26...The early owner's manual lists the helicopter engine as a 23, the latest manual says it's a 26, same hp and torque numbers, same bore, 34mm..