This four-stroke O.S. FS-91 cutaway model airplane engine was manufactured by O.S. Engines of Japan, in the 1980s. The partial cutaway of the cylinder block exposes the piston, crankshaft, and camshaft. Read our article a the founder of O.S. Engines, Mr. Shigeo Ogawa.
O.S. FS-91 Cutaway Model Airplane Engine
