Re: loss of power
29" wheels and the engine is still revving up? You have a good one. Your problem is indicative of a too small main jet. Using taller gearing will only make it worse.
It's the gold looking part that the slide needle goes down into. You can remove it by removing your float bowl, and looking inside there, it has a slot like a screw and a hole in the middle.
You can richen your mixture a bit by leaning your fuel to oil ratio, like from 16:1 to 36 or 40:1.