Hi. Bringing this thread to life as I am also experiencing this issue. VFR750F 86 model (RC24) Only in 6th gear: Sometimes when I let off the throttle it makes a strange clunk-noise. Just changed chain and sprockets, but still present. I am afraid it could be transmission issues. It has been like that as long as I have owned the bike (2 sessions) No issue at all in the other gears... Would love to hear from you guys that had this issue if it was resolved.
Aside from it maybe being normal, get the back wheel off the ground, put it in various gears and rotate the wheel back and forth. Are the rear hub cush rubbers OK? However, there is usually some driveline slack, and maybe it shows up in higher gears.