To throw a little more light on this old chestnut...
I asked a reputable bike mechanic about ST1300 valve inspections, admitting mine had never been touched, and that the general consensus from anyone who had the job done was "They were fine!" His response was there are no obvious symptoms of their being out of spec, but if they were, the engine damage could be serious. He did say that if the engine was hard to start, then valves might be the problem. Mine always starts promptly.
I put Ruby2sday in to have all the fluids changed and plugs changed (I've done plugs myself, and the rear right one is quite difficult to access, and a professional is welcome to the brake bleeding).
When I picked her up today the verdict was the valves were well within specs! That's after 123,500 kays, gents. The head cover gaskets cost $131.60. A fair bit of the $575 labour would have been the valve inspection.
So if you're feeling a bit short of cash and worried about your valves, don't stress- Hondas are wonderfully engineered.