done a bit of a refurbishemnt over the last couple of days, the rad fitted to my bike was full of bent fins and had dirt and crap all over it, thought it was way past its best but had a go at cleaning it,the process was as follows

drilled out the self tappers holding the grill on (correded beyond)
gave that some serious hammer with the wire wheel.
Sprayed the rad core with degreaser for a couple of days, soaked it in the kitchen sink in washing powder of an hour and brushed it out, then gave it some with a compressed air line, after all that it was fairly clean, spend an hour or so straightening fins, then scrubbed of the old dirt with a scotch pad and gave it a few coats of paint, looks as good as new now!! just going to rivet the grill back on tonight