This is the Thunder Tiger RL .56H Ringed Helicopter Engine. FEATURES: XC2 composite coating on cylinder liner to extend engine life and an etched criss-cross pattern to minimize friction Dual needle carburetor with a heat insulator mount and push-pull throttle lever Oversized CNC machined red anodized cylinder head Three year limited warranty through Hobby Services beginning at date of purchase INCLUDES: Thunder Tiger RL .56H Ringed Helicopter Engine with R3 Redline Glow Plug, two head shims, instructions, 2.5 & 3mm hex wrenches REQUIRES: Fuel: Heli blend with 10-30% nitromethane and 20% lubricant content Field equipment SPECS: Displacement: 0.553 cu in (9.05 cc) Bore: 0.906" (23mm) Stroke: 0.858" (21.8mm) RPM Range: 2,000 - 21,000 Output: 2.23 hp @ 17,500 RPM Weight: 13.8oz (390g) Distance Between Mounting Hole Centers Same Side: 0.71" (18mm) Distance Between Mounting Hole Centers Opposite Side: 1.7" (43.5mm) Width at Mounting Tabs: 2.04" (52mm) Width of Crankcase Below Mounting Tabs: 1.4" (35mm) Length from Backplate to Front Bearing: 2.9" (73.4mm) Length from Backplate to end of Crankshaft: 4" (102mm) Height from Mounting Tab/top of Cylinder Head: 2.9" (73mm) Heigth from Crankcase bottom/top of Cylinder Head: 3.5" (90mm) Width of Cylinder Head: 1.8" (47mm) Carburetor Settings: NOTE, carburetor has been preset at factory and should not require large adjustments Needle Valve: Three turns open from closed position Mixture Metering Screw: No more than 1/2 turn at a time, turn clockwise to lean mixture or counter-clockwise to richen mixture jxs 06/28/11 ir/jxs