This is the O.S. Engines 91 HZ-R 3D Speed Helicopter Engine in Black. ****** Because of the competition nature of this engine,****** ******it is NOT covered by the O.S. 2 Year Warranty.****** FEATURES: Designed for all-out 3D competition Demand Regulator System ensures consistent fuel delivery from full to empty 165° exhaust timing for optimal horsepower and stable hovering Newly designed combustion chamber shaped to match the big bore carburetor and advanced exhaust cylinder timing 61F Big Bore carburetor is designed to develope stable horsepower at 70-80% throttle which is widely used in 3D flight Crankshaft counter-weight reduces vibration at high RPM INCLUDES: 91 HZ-R 3D Speed Helicopter Engine with #8 Glow Plug, Aluminum Check Valve, 0.008" (0.2mm) Head Gasket,, Control Arm 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: 0.91cu in (14.9cc) Bore: 1.091" (27.7mm) Stroke: 0.976" (24.8mm) Output: 3.6 PS, 3.55 HP/15,500 RPM Practical RPM Range: 2,000 - 16,000 RPM Weight (w/o Muffler): 21.27oz (603g) Crankshaft Size: 5/16-24 Height from crankcase bottom to top of cylinder head: 4" (103mm) Height/bottom of mounting tab to top of cylinder head: 3.1" (79mm) Distance between mounting hole centers same side: 0.98" (25mm) Distance/mounting hole centers opposite side: 2" (52mm) Distance/center of muffler screw holes: 1.6" (42mm) Distance/bottom of mounting tab to muffler screw holes: 1.7" (42.8mm) Distance/crankshaft center to throttle control arm: 1.6" (42mm) Length from front bearing to backplate: 3.3" (84mm) Length from backplate to end of crankshaft: 4.5" (116mm) Width of crankcase below mounting tabs: 1.7" (43mm) Width between mounting tabs: 2.4" (61mm) Carburetor Adjustments- High Speed Needle Valve: Turn approximately 30° (3-4 clicks) during initial adjustments, then approximately 15° (1-2 clicks) when making final adjustments Medium Speed Needle Valve: Turn approximately 30° (3-4 clicks) at a time jxs 04/08/11 ir/jxs