knocking noise on shogun comes and goes

[leeburn]

I have a knocking noise and judder that comes and goes on my 2004
SWB shogun. Had the tracking done wnd this seemed to sort it out for
A while but the intermitten judder came back. My local garage is not sure
What the issue is, so wondering if anyone had similar issue with their shogun.
Wheels all balanced, tracking sorted, recent brake pads and calipers on the front.
Cheers.