Technically (happy to be corrected, those PCs on the board!), I beleive the tax disk is supposed to be on the left (so can be read from the pavement) and forward of the footpegs. On wifey's monnie it is on the headlight mounting, but I could not find anywhere on the 749 that was suitable. I would be very surprised (and immensely disappointed) if you were fingered for having a valid tax disk, but mounted in the wrong position on the bike!
