>>1033709The black plastic bit is a wrench for tightening the crank fixing bolt that pulls the two halves together. These wrenches (pic related is another design that does the same thing) are intentionally very small in order to avoid over-torquing those bolts.
>>10337101. Those late 80's Centurions are well regarded bikes, quality components, really nice frames. I have an '87 Ironman (with updated components) and it's one of the best riding bikes I've ever owned.
2. But unfortunately, that frame is definitely too big for you, so you're going to be much better served by selling it and getting something that actually fits. See if you have any bike shops near you that deal in used bikes and could give you some trade in value - if that's not an option, I'd expect that bike, in the condition we can see, to be worth $150-200 on a typical Craiglist page, a little more if you live in a bigger city where demand for used bikes is high.
