O.S. FS-120 III Surpass Ringed 1.20 4-Stroke w/Pump

Tower Stock# OSMG0935  •  Manufacturer Stock# 35540
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Notes from our tech department:
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 wCarburetor and F Glow Plug
One Muffler wManifold
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 syntheticcastor 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: 516-24
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.
5-7-97 djg
updt lmm 33109



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