"With experience born on the raceways and roadways and a dedication to innovation, there's plenty of reasons to insist on the new Honda GX660 V-Twin engine. There's superior engine design, with a 90 configuration that reduces vibration and allows a compact footprint. There's superior construction, with a forged steel crankshaft and an integrated cylinder head. Fewer parts means better durability. There's a digital CDI ignition coil that ensures improved fuel economy and lowered emissions. There's even improved air cleaning, meaning that you can wait 5 times longer between filter changes. Honda gives their engines a 3-year limited warranty. Bolt Circle in. 7 3/4, EPA/CARB Approval California Air Resource Board Yes, Shaft Rotation From PTO Shaft Side Counterclockwise, Torque ft./lbs. 35.2, Shaft Output Vertical, Rated Power HP 21, Lubrication System Full pressure, Ignition System Digital CDI, Crankshaft 1 1/8 x 3.8, Start Type Electric, Engine Displacement cc 688, Engine Type Air cooled, Bore x Stroke in. 3.1 x 2.8, Carburetor 2-barrel, fuel cut solenoid, inner vent, Compression Ratio 9.3 1, Cylinders qty. 2, Oil Capacity qt. 2.3, Shaft Length in. 3.8, Air Cleaner Type Dual element, Governor System Mechanical, Shaft Diameter in. 1 1/8. Full pressure lubrication system Forged steel connecting rod Mechanical governor system 50-state compliant engine"