This is the O.S. .91HZ F3C Competition Helicopter Engine.

FEATURES: Designed specifically for F3C aerobatic competition
          Rectangular heat sink allows engine to be enclosed entirely inside
            cooling shroud
          61-E carburetor with thermal insulator to block heat and a needle
            valve control lever to control mixture from transmitter, carburetor
            has three adjustment controls that enable independent adjustment at
            idling, hovering and high speed
          Five holes in the top of the piston route gases to the piston ring
            from within to form a tighter seal with minimum blow by
          Ball bearing supported crankshaft
          Heat sink type backplate
          Two year limited warranty through Hobby Services beginning at date of
            purchase

INCLUDES: O.S. .91 HZ F3C Competition Helicopter Engine with #8 glow plug,
            needle control lever, extra 0.2mm head gasket, cap screws and
            instruction manual

REQUIRES: Fuel: 10%-30% nitromethane with at least 18% lubricant. Lubricants
            may be either castor or synthetic oil or castor/synthetic blend.
          Field Equipment: glow starter, fuel bulb, fuel can filter, fuel pump
            hexagonal starting shaft (depending on brand of helicopter)
            electric starter, battery and fuel tubing
          Muffler-Depending on heli

SPECS:    Displacement: 0.91 cu in (14.95 cc)
          Bore: 1.09" (27.7mm)
          Stroke: 0.98" (24.8mm)
          Output: 3.4 PS, 3.35 HP @ 15,000 RPM
          Practical RPM Range: 2000-16,000
          Weight Without Muffler: 1.36lb (618g)
          Crankshaft Size: 5/16-24
          Height from crankcase bottom to top of cylinder head: 3.9" (99mm)
          Height/bottom of mounting tab to top of cylinder head: 3.2" (81.2mm)
          Distance between mounting holes same side: 0.98" (25mm)
          Distance between mounting holes opposite side: 2.04" (52mm)
          Distance between muffler screw holes: 1.6" (42mm)
          Distance/bottom of mounting tab to muffler screw holes: 1.7" (42.8mm)
          Length from front bearing to backplate: 3.3" (84mm)
          Length from backplate to end of crankshaft: 4.9" (125.6mm)
          Width of crankcase below mounting tabs: 1.7" (43mm)
          Width between mounting tabs: 2.4" (61mm)

          Carburetor Needle Settings:
            High Speed: 2 turns out from fully closed
            Mid Range:  2 turns open
            Mixture Control (low speed): indentation on screw head straight up
              and down (vertical)

                                                                   jxs 10/14/10
                                                                         ir/jxs