Those are NGKs but not the ZFR5Ns, which will probably work better for you. Nevertheless, looks like you need to pay some attention to your carburetor and/or choke. Carburetor operation and repair manuals and links to training movies and carb repair/modification threads are posted here for free download.
I a ajusted the carb seems les rich will drive a few days and go pull plugs againI'm a little on the fence about this what we're seeing on these plugs, actually. Could be rich running, could also be oil getting into the combustion chamber via any of the usual suspects (valve guides/seals, rings). If the black gunk on the plugs is completely dry and fluffy/powdery, that's fuel -- too rich. If the gunk is at all "wet" looking, and it's more gummy than powdery, that's oil. Severe cases of either are obvious; less-severe cases like what you're showing us aren't as obvious.