Set of 4 Genuine NGK CR9EIX (3521) Iridium IX Performance Spark Plugs – Heat Grade 9 For Motorcycles, Scooters & ATVs. NGK Part Number: CR9EIX. This Heat Grade 9 CR9EIX spark plug set is a performance upgrade compatible with a wide range of sport motorcycles, scooters and ATV quad bikes with small high-compression two-stroke and four-stroke engines.
