There is an old war movie B Movie call Nam's Angels in which a gang of Vietnam Veteran Hells Angels type bikers called "The Devil's Advocates" are recruited by the US Army, for a mission to the Cambodian jungle order to rescue an American diplomat/CIA Agent.
In the movie they ride converted Yamaha bikes. Many are converted by welding armor plating with submachine guns on the handlebars. There is three-wheeler modified from a Harley-Davidson frame with a Volkswagen rear end that is armed with heavy .50 caliber machine guns and a multiple rocket launcher from a helicopter.
In order to open fire on enemy soldiers in trees or towers the gang does wheelies whilst firing their weapons.
The bases for this movie come from a telegram the white house got on 19 November 1965. Sonny Barger the "Maximum Leader" of the Hells Angels motorcycle club sent a telegram to President Johnson offering the Angels as "guerrilla fighters" in the Vietnam War.
While I could find the original source on this there is an online article By Peter Carlson of the Washington Post dated Wednesday, August 9, 2000 in which he talk a 1965 press conference in which Mr. Barger talks about the Telegram to then President Lynd Johnson. This was done apparently to boast the Club image.
http://www.nolimitsonline.com/biker_life1.htm
http://en.wikipedia.org/wiki/Nam's_Angels