Because why not? I see it often in the datasheets and partslists and decided to get the Spark Arrestor Guide from 1976 from the library. There might be some two-stroke ones between them, but I think that's a forgivable mistake. Right? Right.
Here is the list: https://4-stroke.net/library/honda-spark-arrester-guide.html
And here is the entire book: pdf Spark Arrester Guide (1976) (65.53 MB)