This is the O.S. Engines 91 HZ-R 3D Speed Helicopter Engine in Black with the 91 PowerBoost Tuned Pipe. ****** 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 DRS (Demand Regulator System) ensures a steady fuel supply for 3D flights 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 61G Big Bore twin needle carburetor is designed to develope stable horsepower at 70-80% throttle which is widely used in 3D flight PowerBoost pipe is constructed of polished natural finish aluminum and was developed exclusively for flights with 90 size helicopters INCLUDES: 91 HZ-R 3D Speed Helicopter Engine, with PowerBoost Pipe, Exhaust Tube and Mounting Hardware, #8 Glowplug, Check Valve, 0.2mm Head Gasket 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 SPECS: Engine- Displacement: 0.91cu in (14.9cc) Bore: 1.091" (27.7mm) Stroke: 0.976" (24.8mm) Power Output: 3.6hp / 15,500 RPM Practical RPM Range: 2,000 - 16,000 Weight (w/o Muffler): 21.27oz (603g) Crankshaft Size: 5/16-24 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 Idle Mixture Control Screw: Turn approximately 5° at a time, turn left to enrich idle mixture and right to lean mixture Height from crankcase bottom to top of cylinder head: 3.9" (100mm) Height/bottom of mounting tab to top of cylinder head: 3.1" (79mm) Distance between mounting holes same side: 0.98" (25mm) Distance between mounting holes opposite side: 2" (52mm) Distance between muffler screw holes: 1.6" (42mm) Distance/bottom of mounting tab to muffler screw holes: 1.8" (42.8mm) Distance throttle lever to center of engine: 1.6" (42mm) Length from front bearing to center of engine: 2.2" (56.4mm) Length from front bearing to backplate: 3.3" (83.8mm) Length from backplate to end of crankshaft: 4.6" (118mm) Length from backplate to center of engine: 1.1" (27.4mm) Width of crankcase below mounting tabs: 1.7" (43mm) Width between mounting tabs: 2.4" (61mm) Pipe- Length: 12.3" (313mm) Diameter: 2.0" (50mm) at engine attachment point Exhaust Outlet Diameter: 0.20" (5mm) Weight: 7.9oz (225g) jxs 04/08/11 ir/jxs