RE: 25cc toro on a diet
I have one of those. I was going to buy a cheap clone G-26 cylinder for it, but then after some research I found that you would either have to weld up the crankcase, or JB Weld it, and grind out the transfer ports in the crankcase a bunch to fit the good cylinder. I set it aside on a shelf figuring some day I would convert it anyway just to see how the power would be with the stock setup. One worry would be how to richen up the carb to account for running no air filter and a decent flowing muffler...
Are you going to get busy on yours?
AV8TOR