I have a set of C5 forks for my current project and the hex bar tool which fits all my other RE forks doesn't quite fit the top cap on the C5's. I coughed up for a 12mm Allen key socket, and lo and behold, I have access. The footrest bar and our hosts' tee bar use a 1/2" a/f hex section or 12.7mm
http://www.ebay.co.uk/itm/BGS-12-mm-All ... 3f667c818c
If you read the tutorial you will see what other sizes are needed.
I would point out that the tutorial is for the older style C5 and B5 forks with the leading axle sliders and fork stanchions that screw into the casquette or whatever top yoke you're using. Late forks with the plain stanchion tops have a screw in cap with a couple of flats, I posted an Indian Youtube video a while back showing the mechanic unscrewing these anti-clockwise, as they seem to be on a normal right-hand thread, unlike the earlier C5/B5 forks. As far as I can tell the internals are the same.
A.