This is the 120AX Special Ringed Aircraft Engine from O.S. Engines. FEATURES: High performance two stroke engine designed for sport and scale models Compact size enables it to fit into most cowls Crankshaft port timing was modified to increase power at high RPM Velocity stack on carburetor adds acceleration at high RPM 0.1mm head gasket increases compression ratio for more power 1mm deeper machining to enlarge intake port for greater RPM Two year limited warranty through Hobby Services beginning at date of purchase INCLUDES: 120AX Special Ringed Aircraft Engine, #8 Glow Plug, 70D Carburetor with Velocity Stack, Instruction Manual, Prop Washer & Nut and Needle Valve Extension Set REQUIRES: Fuel: Two-Stroke with 18% lubricant and 5-20% nitromethane Muffler: E-5020 "Power Box" Propeller: 15x10-12 or 16x8-10 SPECS: Displacement: 1.218 cu in (19.96 cc) Bore: 1.197" (30.4mm) Stroke: 1.083" (27.5mm) Practical RPM Range: 1,800 - 9,500 Output: 3.35 PS (3.155 HP) @ 9,500 RPM Crankshaft Size: UNF5/16-24 Distance between Mounting Hole Center Same Side: 0.98" (25mm) Distance between Mounting Hole Center Opposite Side: 2.3" (58mm) Height/bottom of Mounting Tab/top of Cylinder Head: 3.4" (85.7mm) Height/bottom of Crankcase/top of Cylinder Head: 4.3" (109.2mm) Length from Backplate to front of Drive Hub: 3.9" (100.2mm) Length from Backplate to end of Crankshaft: 5.5" (139.9mm) Length from Backplate to Center of Crankcase: 1.2" (30.4mm) Length from front of Drive Hub to end of Crankshaft: 1.6" (39.7mm) Width at Mounting Tabs: 2.6" (67mm) Width of Crankcase below Mounting Tabs: 1.8" (46.5mm) Height from Crankshaft Center to Needle Valve: 1.3" (33.8mm) Distance between Muffler Mounting Hole Centers: 1.9" (48mm) Carburetor Settings; Needle Valve, 2 - 2.5 turns out from fully closed as a starting point Mixture Control Valve, Close throttle rotor and screw in Mixture Control Screw until it stops, then unscrew approximately 3/4 turn. NOTE, Mixture Control Valve is factory set and should require only small adjustments. Refer to instruction manual for full break-in procedures. jxs 06/11/12 ir/jxs