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FS120III Pump Ring 70N Carb

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FS120III Pump Ring 70N Carb

O.S. Engines OSMG0935 Airplane Engine Nitro
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  • FS120III Pump Ring 70N Carb

    This is one of the O.S. Surpass series of 4-stroke model engines.
    The Surpass series is the 2nd series of 4-stroke engines (The 1st series was
    the FS series, discontinued and replaced by the Surpass series around 1986-7).
    "Surpass" refers to this series gaining 30% more power than the previous
    FS series.


    Specially developed PD-07 pump
    New 70N carb
    Ball bearing-supported camshaft and crankshaft
    New F-5020 Silencer
    Two year warranty


    One Assembled Engine w/Carburetor and #F Glow Plug
    One Muffler w/Manifold
    One Set of Instructions, O.S. Poster, and Decal
    (Mounting Template Is No Longer Included per O.S.)
    One additional coarse needle for less sensitive carb adjustment.


    Fuel: 5%-15% nitromethane with 18% lubricant. Synthetic, castor, or
    a synthetic/castor blend may be used.
    NOTE: Certain four-cycle fuels cannot be used due to low oil content.
    However, SOME four-cycle fuels such as the Wildcat 4-Cycle 15%
    (CATP9109) may be used because it has 18% oil content.
    When choosing fuels for this engine, the modeler must be sure to
    select a fuel with at least a 18% lubricant content.
    Starting and Field Equipment.
    Propeller (see SPECS)


    Bore: 30.4mm (1.20")
    Stroke: 27.5mm (1.08")
    Power Output: 2.1 PS, 2.07 HP at 12,000 RPM
    Practical RPM Range: 2,000 - 12,000 RPM
    Weight-Without Muffler: 32.5oz (921g)
    Weight-With Muffler: 35.3oz (1000g)
    Crankshaft Thread Size: 5/16-24
    Valve Clearance: Between .04mm and .1mm (or between .0015" and .004",
    measured between the valve tip and rocker arm)
    Length: 102mm (4.09") from backplate to the front of the drive washer
    Width: 47mm (1.85") width of engine neglecting the mounting flanges
    58mm (2.28") distance between the mounting hole centers
    Height: 139.5mm (5.49")
    Suggested Prop(s): 14x9, 14x10, 14x11, 15x8, 15x9, 15x10, 16x6,
    Construction: Aluminum and Aluminum alloys

    Needle Settings: High Speed: 1.5 turns out from fully closed
    Low Speed: 2.5 turns out from fully closed with the
    throttle fully closed


    Some differences between 2-Stroke and 4-Stroke engines:
    4-Strokes are quieter.
    4-Strokes get better Fuel Economy
    2-Strokes generate More RPM (11,000-13,000 RPM with prop
    and 4-Strokes rev to around 9,500 RPM)
    4-Strokes generate much more torque and will swing a larger prop.
    4-Strokes have a more realistic sound, like a real aircraft engine.

    The new Surpass engines (Version II and III) have more power than
    their predecessors and they also have more corrosion prevention
    on the inside of the crankcases.
  • O.S. Engines FS120III Pump Ring 70N Carb Parts List (1 items)

  • O.S. Engines FS120III Pump Ring 70N Carb Hop-Ups & Optional Accessories (0 items)

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