Shouldn't really be too difficult to obtain from a hydraulics shop or bearing supplier, but just in case any of my Hondabuddies are having difficulty in finding them, they're here:
http://cgi.ebay.com/ebaymotors/Honda-CB ... 679wt_1163
Before replacing, don't omit inspecting the pushrod; if it's grooved from wear where the lip seal seals (or doesn't, as the case may be!) then the rod will need replacing, as it will still leak even with a new seal. An alternative, in this case, would be to obtain a 7x21x6 seal and then have the last 25mm or so of the rod turned down by an expert machinist with a lathe; but get the seal in that size first -- and the rod is
very hard!
Edited to correct a minor grammatical error.
