[Dave20046]

I've put uprated springs and 15w oil in mine, it clunks when I go over a pothole but it doesn't sound out of the ordinary as the front end is rock solid, you kind of expect it. I'm not sure if it's the same clunk you're thinking of though.
Last time I had knocking noise it was the brakes dragging and pulling the floating disc about, might be worth checking that but it's very unlikely you'll be able to hear that with the motor on.