This is the O.S. 21XM Version II Air Cooled Outboard Marine Engine. ****** Because of the competition nature of this engine,****** ******it is NOT covered by the O.S. 2 Year Warranty.****** FEATURES: Designed expressly for small and medium size outboard boats Installed aluminum tilt transom mounting plate Preassembled outboard unit with flexible propeller Blue anodized aluminum heat sink head 42mm carbon fiber propeller 20J carburetor INCLUDES: O.S. 21XM Version II Outboard Marine Engine, Muffler, Mounting Plate, #8 Glow Plug, Propeller, Outboard Unit, Steering Arm and Instructions REQUIRES: Glow Fuel: 10-30% nitromethane content, use 20% for break-in Glow plug igniter, starting belt and shore equipment SPECS: Displacement: .21 cu in (3.5cc) Bore: 0.654" (16.6mm) Stroke: 0.630" (16mm) Practical RPM: 3,000 - 25,000 Power Output: 1.3 PS, 1.28 HP @ 25,000RPM Weight: 24oz (682g) Carburetor Settings: Needle Valve; 2.5 turns from fully closed Mixture Control Valve: Shoulder portion exactly at a tangent to the throttle rotor hole Distance between mounting hole centers same side: 0.98" (25mm) Distance between mounting hole centers opposite side: 1.5" (37.5mm) Distance/outer mounting hole centers on steering arm: 2.5" (64mm) Width of muffler: 1.8" (46mm) Distance from flywheel to skeg: 8.6" (219mm) Distance from mounting plate bottom to skeg: 3.4" (86mm) Distance from mounting plate top to flywheel: 3.5" (87mm) Distance from mounting plate to end of cavitation plate: 7.2" (183mm) Distance from mounting plate to prop attachment point: 5.9" (149.5mm) Distance from bottom of mount to driveshaft center: 1.3" (34.5mm) Height of mounting plate: 1.8" (46mm) COMMENTS: This Engine STARTS AND RUNS IN A CLOCKWISE DIRECTION at the starter cone. Any attempt to start engine in a counter-clockwise rotation may cause serious damage to the engine. Because of the clockwise rotation, the crankshaft has reverse threads. jxs 05/25/11 ir/jxs