OS MAX 50SX model airplane engine for control line stunt use. This engine has obviously not been run but I listed it as "used" because the mounting holes have been enlarged. The engine is extremely clean, there are no run marks on the piston, there is no fuel residue, and no exhaust residue, and no combustion residue. This is a ringed engine and even though the ring has not been "seated" it still has excellent compression and of course the bearings are smooth and quiet. It has an OS venturi and a Super Tigre type NVA has been installed through the venturi. Glow plug is a new OS #8. Muffler and muffler mounting bolts are included and it is in it's original box.