Thank you for the interim report. It sounds as if there is probably powder throughout the carburetor though, rather than just in the main jet. The deterioration in behaviour as you get down toward the idle jet's influence suggests that is partly or wholly blocked - which is not surprising since its orifices are much smaller than the main jet. Let's see how you go with a clean jet, but if that is not sufficient, the carburetor will have to come off the engine and be cleaned in detail. Not difficult, but it will cost a few dollars for gaskets and carburetor cleaner. If you were going to do this regularly I'd suggest you get the special tools recommended by Honda, but if you keep your mower closer to home in future it may never happen again, so that wouldn't be worthwhile.
