"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 even gives their engines a 3-year limited warranty. Bolt Circle in. 7 3/4, Torque ft./lbs. 35.2, Governor System Mechanical, EPA/CARB Approval California Air Resource Board Yes, Ignition System Digital CDI, Engine Displacement cc 630, Bore x Stroke in. 3.1 x 2.8, Shaft Length in. 3.11, Start Type Electric, Compression Ratio 9.3 1, Engine Type Air cooled, Air Cleaner Type Dual element, Cylinders qty. 2, Carburetor 2-barrel, fuel cut solenoid, inner vent, Shaft Rotation From PTO Shaft Side Counterclockwise, Lubrication System Full pressure, Oil Capacity qt. 2.3, Shaft Diameter in. 1. Full pressure lubrication system Forged steel connecting rod Mechanical governor system 50-state compliant engine"