Which parts of the kit are of such low quality that you just discard them and replace them with something better as you're building the kit?
fuel line: That piece of aquarium tubing probably isn't even meant to have gasoline in it. Throw it away. For about a dollar a foot, you can get real fuel line at an auto parts store. And, be sure to use hose clamps, which are not included in the kit.
spark plug, wire, and cap: use NGK or some other reputable Japanese brand.
Gas cap: What junk! Every one I've gotten has become useless when the little tabs get stuck inside the cap, so you can't screw it on right.