This is the O.S. Max 75 AX ABL Aircraft Engine with Muffler. FEATURES: Same mounting dimensions as the O.S. Max .61FX Advanced Bi-Metallic Liner process uses a double layer of plating material rather than one thick layer. This helps the metal bond to the cylinder and makes the plating more durable. Also, the plating process is more consistent, resulting in a more precise fit between piston and sleeve for better compression and longer life. Power Box muffler design provides more volume for increased power in a very compact shape Angular head design offers increased surface area for better cooling Ball bearing-supported crankshaft 61A carburetor with diagonally placed needle valve eliminating remote needle valve placement Two year limited warranty INCLUDES: O.S. Max 75 AX ABL Aircraft Engine with E3010 muffler, carburetor, #8 glow plug, illustrated instruction manual REQUIRES: Aircraft blend fuel containing 5%-20% Nitromethane with at least 18% lubricant SPECS: Displacement: 0.75 cu in (12.3cc) Bore: 1.02" (25.8mm) Stroke: 0.93" (23.5mm) Practical RPM: 2,000-16,000 RPM Power Output: 2.4 PS, 2.37HP/15,000 RPM Weight: 20.39 onuces (578g) w/o muffler 26.46 ounces (750g) w/ muffler Recommended Props: 14x6, 14x8, 15x7 Crankshaft thread size: 5/16-24 Distance from center of engine to drive hub: 2.62" (66.6mm) Distance between exhaust bolt mounting holes 42mm Height from crankcase bottom to top of cylinder head: 4.07" (103.5mm) Height/crankshaft center to top of cylinder head: 3.20" (81.5mm) Width including mounting tabs: 2.4" (61mm) Width not including mounting tabs: 1.67" (42.6mm) Width between mounting holes same side: .98 (25mm) Width between mounting holes opposite side: 2.04" (52mm) Diameter of muffler body: 1.92" (48.8mm) Angle of muffler in relation to engine: 4° Length from end of crankshaft to back of crankcase 5.09" (129.5mm) 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) jxs 4/12/07 ir/jxs updated jpg 7/11/07