O.S. FR7-420 4-Stroke Engine

The brightest star in 4-stroke appearance and performance!

The "Golden Era" looks of the FR7-420 Sirius are matched by its superb power output and rich, realistic sound.
Specifications:
Displacement: 0.6071 cu in x 7 (9.95 cc x 7) Bore: 0.944 in (24.0 mm) Stroke: 0.866 in (22.0 mm) Practical rpm: 1,500-7,000 Weight: 111.7 oz (3.167 g) Includes: 7 type F glow plugs, valve adjusting kit, radial mount & hardware kit, needle valve extension cable, glow plug cable set and aluminum case Recommended props: 22x10, 22x11, 22x12, 23x8, 23x9, 23x10, 23x11, 23x12, 24x8, 24x9, 24x10, 24x11, 24x12, 26x8
  • The vintage 7-cylinder design is a scale airplane modeler's dream
  • Individual V-shaped valve covers add to the scale appearance, and make this engine compatible with several airplane styles
  • Main internal parts such as the crankshaft, cam holder and reduction gear are all plated to resist corrosion
  • Air-fuel mixture is distributed equally to each cylinder to ensure stable, long-lasting idle
V-shape
V-shaped valve layout matches various scale model airplanes.
Optional Collector Ring
Optional Collector Ring collects exhaust from each cylinder and vents it through two tubes.
Internal Parts
Main internal parts such as crankshaft, wrist pin, cam holder and reduction gear are all plated for anti-corrosion. Selected material and proper thermal treatment ensure high durability of the parts.
Impeller
The impeller distributes balanced air-fuel mixture to each cylinder, which has realized long lasting stable idling.
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