Chain-driven Overhead Cam design offers superior power and performance with an automatic decompression system to reduce the required pulling force by 30 to 40 percent, and ensure starting on the first pull. EX engines start instantly even at temperatures as cold as -10 degrees C without any perceptible kickback. Dual ball bearing crankshaft support offers maximum stability under demanding loads. The crankshaft is made of spheroidal graphite cast iron, and the crank pin is high-frequency induction hardened. Both the crank sprocket used to drive the chain, and the gear used to drive the governor gear, are pressed on the output end of the shaft. Heavy-duty piston rings coupled with a cast-iron cylinder liner resist wear and ensure a long engine life.