Instruction Manuals:

Manual 1 (884 KB)

      O.S. has Updated the .25 SF with this New High-Performance .25 FX.
This Engine may be used in Sport and Aerobatic Aircraft. The FX is Designed to
Use a Muffler or Tuned Pipe. Comes with a 2-Year Warranty.

FEATURES: Remote Needle Attached to the Backplate keeps fingers away from prop
          Twin Ball Bearing-Supported Crankshaft
          Schnuerle Porting (Schnuerle scavenging)
          Advanced Bi-Metallic Liner. This process uses a double layer of
            plating material, rather than one thicker layer. This helps the
            metal to bond to the cylinder, and is more durable. Also, the
            plating process is more consistent, resulting in a more precise
            fit between piston and sleeve, for better compression, longer life.
          Side Exhaust
          One-Piece Crankcase

INCLUDES: One Expansion Style Muffler
          One Set of Instructions, Decal, and Poster
          One Assembled .25 FX w/Carb

SPECS:    Displacement:  4.07cc (.2485 cu in)
          Bore:   18mm (.708")
          Stroke: 16mm (.630")
          Horsepower: .84 BHP at 18,000 RPM
          Weight: 248g (8.8oz)  10.8oz w/muffler
          Length: 75.6mm (2.98") distance from the backplate to drive washer
          Width: 30mm(1.18") width of engine neglecting engine mounting flanges
                 38mm (1.50") distance between centers of the mounting holes
          Height: 75.5mm (2.97")
          Crankshaft Thread Size: 1/4-28
          Recommended Props: Pattern Flying: 9x5, 9x6
            Pattern Flying if a tuned pipe is used: 9.5x5
            Sport Flying: 9x5, 9x6, 9.5x5, 10x4, 10x5
          Practical RPM Range: 2,500 - 19,000 RPM

         High Speed Needle: 1.5 - 2 turns out from fully closed
         Low Speed Needle:  2mm gap between the needle and spray bar at full
                            throttle (looking down the neck of the carb)

REQUIRES: Long Glow Plug (O.S. #8 recommended OSMG2691)
          Fuel with 18% (minimum) lubricant content and 5%-15% Nitromethane
            (All 5%-15% fuels we carry meet these requirements)
                                                                          ir/jl
                                                            updated jpg 9/20/05
                                                               updt lmm 3/27/09



– If you need more information, use these O.S. resources –

Click Here: Manufacturer's Product Web Page
E-mail: enginesupport@hobbico.com
Web Site: http://www.osengines.com/
Phone: 217-398-8970


 
Postal Address:
O.S.
3002 N. APOLLO DRIVE, SUITE #1
CHAMPAIGN, IL 61822  








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