CDHPOWER Support Team. - The racing cylinder head increases the horse power of your 80cc / 66cc 2-Stroke Bicycle Engine and this greatly cools off the engine. Higher performance Racing head for 2 stroke kit 80cc/66cc; Fully cnc machine made; Alum Design; The racing cylinder head increases the horse power of your 80cc / 66cc 2-Stroke Bicycle Engine and this greatly cools off the engine.