i know how ya feel man. i got myself a dpro 160 a week or so back. out of the factory the rear brakes were stuffed, the metal pin was broken and the pads just kept falling out. the exhaust wasn't done up properly, and upon inspection i know why, it was cos the person who did it up cross threaded the bolt, which then blew out my exhaust gasket.
since getting it i've changed the tyres, chain, handle bars, rear brake set up, locktited every bolt, bled all the brakes, did all the maintenance including vale clearances, replaced stripped head bolts (which was a pain in the ass to get out). then i'll be putting on an oko as it's running a bit lean at the moment and cant be bothered stuffing around with the stock carby.
but after doing all this i'm sure i'll have a very well set up bike, and will know how to do any work on it in the future. and it's all apart of the fun anyways