HTS code 8407.33.90 covers "Spark-ignition reciprocating or rotary internal combustion piston engines › Aircraft engines › Of a cylinder capacity exceeding 250 cc but not exceeding 1,000 cc › Other" under the US Harmonized Tariff Schedule. This is the official duty rate charged by US Customs when this product is imported into the United States, sourced directly from the U.S. International Trade Commission and refreshed daily.