Damn kids: The Bōsōzoku.

Wikipedia:

Bōsōzoku (暴走族) (literally "Violent Running Tribe") is a Japanese subculture very similar to car clubs: gangs of young men who share a common interest in designing (often illegal) modifications for cars and motorcycles. These modifications often include removing the silencing features so that more noise is produced. They also engage in dangerous driving, such as weaving from side to side on the road, not wearing crash helmets, and ignoring red traffic lights. Japanese police call them "Maru-So"(police code:マル走)


A typical customized bosozoku bike usually consists of an average Japanese road bike that appears to combine elements of an American chopper style bike and a British café racer, for example: oversized visored fenders like those found on café racers, "sissy" bars and raised handle bars like those on a chopper. Loud paint jobs on the fenders or the gas tanks with motifs such as flames or kamikaze style "rising sun" designs are also quite common. The bikes will often be adorned with stickers and/or flags depicting the gang's symbol or logo. There is also marked regional differences in motorcycle modifications. For example, Ibaraki Bosozoku are known to modify their motorcycles in an extensively colorful, flashy way. They will often have 3 or 4 oversized visored fenders in a tower like way in a motorcycle painted in bright yellow or pink with Christmas light like adornments.

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