DR Evolution Race Cylinder Kit 68ccm – affordable prices and long life, thats Drs motto here. Don’t let the term evolution lead you astray. Still, it’s a solid piece of equipment and well made. Gray Rated Iron/47mm Bore/8700 rpm. Exhaust port enlarged, timing optimized, peripherals such as exhaust and carburetor can, but must not be modified. SIP-TIPP: Various light rolls, new candles. SIP TUNING 2/STANDARD-ROAD LEVEL