I am not familiar with the Ryan 265; however, the Ryan model 264 has a displacement of 28.5 cc (1.7 cu. in.). The bore is 1.31 in. (33.27 mm) and the engine has an operating RPM of 7000. The engine was manufactured by Inertia Dynamics Corp., is an air-cooled 2 cycle with a 1.25 in. (3.75 mm) stroke and an electronic ignition. Average compression for the engine is 90 to 120 psi. I have a manual for this trimmer so if you need further info shoot me an e-mail. Good luck.