"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, Oil Capacity qt. 2.3, Engine Type Air cooled, Bore x Stroke in. 3.1 x 2.8, Air Cleaner Type Dual element, Shaft Length in. 3.8, Start Type Electric, Ignition System Digital CDI, Crankshaft 1 1/8 x 3.8, Engine Displacement cc 688, Governor System Mechanical, Carburetor 2-barrel, fuel cut solenoid, inner vent, Compression Ratio 9.3 1, Cylinders qty. 2, Shaft Diameter in. 1 1/8. Full pressure lubrication system Forged steel connecting rod Mechanical governor system 50-state compliant engine"