The OS FS-60 Open Rocker is a historic four-stroke RC airplane glow engine manufactured by Ogawa Seiki (O.S. Engines). Released in 1976, it marks a major milestone as the very first production four-stroke engine ever offered by O.S.
Displacement: 9.95cc (0.607 cu. in.)
Bore/Stroke: 24.0mm / 22.0mm
Practical RPM: 2,000 to 10,000 RPM
Power Output: 0.6 ps at 10,000 RPM
Weight: 560g
Open Rocker Design: The rocker arms, valve springs, and pushrods are completely exposed. This means they lack an oil bath enclosure and require manual lubrication before or after running.
Historical Eras: The engine was produced between 1976 and 1983 across roughly three distinct versions (MkI, MkII, and MkIII), mostly differing by their cylinder head casting types (e.g., billet heads vs. cast heads) and minor carburetor changes.
