"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, Governor System Mechanical, EPA/CARB Approval California Air Resource Board Yes, Torque ft./lbs. 35.2, Shaft Length in. 3.11, Ignition System Digital CDI, Compression Ratio 9.3 1, Start Type Electric, Bore x Stroke in. 3.1 x 2.8, Shaft Rotation From PTO Shaft Side Counterclockwise, Cylinders qty. 2, Engine Type Air cooled, Carburetor 2-barrel, fuel cut solenoid, inner vent, Lubrication System Full pressure, Engine Displacement cc 688, Air Cleaner Type Dual element, Oil Capacity qt. 2.3, Shaft Diameter in. 1. Full pressure lubrication system Forged steel connecting rod Mechanical governor system 50-state compliant engine"