O.S. Engines - 34810 FS81-A 4-STROKE

O.S. Engines SKU: OSMG0981
O.S. Engines - 34810 FS81-A 4-STROKE
O.S. Engines - 34810 FS81-A 4-STROKE

O.S. Engines - 34810 FS81-A 4-STROKE

O.S. Engines SKU: OSMG0981
Regular price $299.99
  • In stock, ready to ship
  • Inventory on the way
  • Same mounting dimensions as the O.S. Max FS-70 Surpass Ideal fit for 60 size planes
  • Specially designed lubrication system eliminates need for crankcase
  • ventilation 60RA carburetor F5030 muffler with rubber O-ring in multi position manifold to help prevent oil leakage


  • O.S. 81FS-a 4-Stroke Aircraft Engine
  • carburetor
  • muffler
  • header
  • type F glow plug
  • manual


  • Fuel: 10%-20% nitromethane with 18% lubricant.
  • Synthetic castor, or a synthetic/castor lubricant blend may be used.


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 due to its 18% oil content. When choosing fuels for this engine, be sure to select a fuel with at least an 18% lubricant content. Propeller: Sport and aerobatic scale 13x7-9 or 14x6-7


  • Displacement: 0.809 cu in (13.26cc)
  • Bore: 1.091" (27.7mm)
  • Stroke: .866" (22mm)
  • Weight with Muffler: 20.11oz (570g)
  • Practical RPM Range: 2200-10,000
  • Output: 1.3hp @ 11,000 RPM
  • Height from Bottom of Mounting Tab/Top of Rocker Cover: 3.8" (97mm)
  • Width of Crankcase below Mounting Tabs: 1.6" (40mm)
  • Center of Mounting Holes Same Side: .83" (21mm)
  • Center of Mounting Holes Opposite Side: 2" (50.8mm)
  • Center of Front Mounting Hole to Prop Washer: 2.2" (55.5mm)
  • Center of Rear Mounting Hole to Prop Washer: 3" (76.2mm)
  • Center of Crankshaft to Center of Needle Assembly: 1.4" (36mm)
  • Center of Crankshaft to Outer Edge of Carburetor: 1.8" (45mm)
  • Muffler Angle in Relation to Engine: 10°
  • Needle Settings: High Speed: 2.5 - 3 turns out from fully closed
  • Mixture Control (low speed): Flush with carb body, then 1 turn in.

Please allow 2-3 days for your order to be processed and shipped. You will be notified of the shipment tracking number via the e-mail address you have provided us when the package has been sent. Currently, we will only ship to the address that matches the billing address registered to your credit card. Trying to create an order with a credit card that doesn't match your delivery can result in the cancellation of your order.

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