Thanks for the replies.
I've no problem with the effectiveness of Gunk, I've been using it for yrs. What I have a problem with is the way it seems to be absorbed into the pads for a short while and the resulting reduction in brake performance.
I've tried using using brake cleaner on the discs with only limited results, after all I can't spray the pad surface.
I was tempted to try Auto Glym motorcycle cleaner but as the instructions seemed to recommend cleaning the bike before application I stuck with Gunk, which, incidentally doesn't smell nice anymore.
What I was hoping for was something that rinses off totally leaving no residue.
Russ.