A toptip from another Triumph Forum I frequent is to use Harpic Blue toilet cleaner on the exhaust, paint it on, keep it moving for a short while with the paint brush then wash off wi plenty of aqua, makes them brand new :bug_eye. Seems to work on other machines but definetly not all bikes, suppose its exhaust material dependant but a couple of my bikes now look bloody marvelous without being spannered or bloody polish mopped for hours! It doesnt seem to react badly with alloy or any plating but I wash it off sharpish. Try it you'll like it my friends :icon_mrgreen:.
Haven't got any under the sink, but it seems that it's just a dilute hydrochloric acid solution with a few surfactants and perfume.
Aqua
Hydrochloric Acid
PEG-2 Hydrogenated Tallow Ammonium Chloride
Tallowtrimonium Chloride
Isopropyl Alcohol
Laureth-10
Aqueous Solution Of Polymer
2-Propanol
Sodium Chloride
Parfum
Colorant
Suppose it's an readily available HCl source that will dissolve any iron compounds that have formed. Half term now, so my "supply" of HCl has dried for a week. May give Harpic Blue a go ... on a small inconspicuous patch.