raymond65:
thats an interesting question indeed as I have ran into that myself with this '82 650.....
My best guess is the vaccuum operated petcock...... at idle the darn petcock just don't seam to wann'a work very good
check for vaccuum leaks ...that's what I'm doing on mine .... I may esort to disemboweling the petcock and rid myself of the vaccuum operated portion of it ! .... ofcourse if I had the money I'ed just buy a non vaccuum operated petcock from MikesXS.com
other than that I don't know of any secret electrical do hicky that would do it ! gggGary may well know if there is something like that !
lol too many questions on one thread Me thinks ! HAHHAH!
Bob............