No items in your cart

FS120III Pump Ring 70N Carb

Click any image for gallery view.

FS120III Pump Ring 70N Carb

O.S. Engines OSMG0935 Airplane Engine Nitro
In Stock

Add to wishlist
  • 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)

  • Manuals and Support

Language Picker

  • English
  • Español


My Cart

No items in your cart