O.S. Engines

FS56-a 4-Stroke Engine

A big performance boost for 40-size planes!

A new era in O.S. 4-stroke technology, the FS56-a is the first in the “a” Series — with the latest advancements for boosting your plane's performance. It's like giving your 40-size plane a new lease on life. Bolt in the O.S. FS56-a 4-stroke powerhouse, and you and your fellow fliers will all be saying: This engine rates an “a”!
Displacement: 0.569 cu in (9.32 cc) Bore: 0.945 in (24.0 mm) Stroke: 0.811 in (20.6 mm) Weight w/muffler: 16.26 oz (461 g) Practical rpm range: 2400-13,000 Output: 1.0 ps @ 10,000 rpm Includes: 40NA carburetor, muffler