the most stubbornest peewee 50 ever

I don't know if its a peewee or y zinger coz its a 1980's model, I bought it not running, replaced every electrical part on it, rebuilt the top end, put a new carb on it with a new airfilter box and still no go, iv had it running all of three times after all the new parts went on, it ran fine and didn't want to die after about 4 and a half million kicks and each time it started it seemed like a freak thing (out of the blue) it also ran backwards but the rear tyre and the flywheel spin in the rite direction when kicked, I'm at my wits end with this thing, the flywheel seems a tad worn but I don't know if that's it, I checked the reeds n they seem OK (couldn't notice any damage) and checked the kickstarter (it cost me the atf that was in it but proberbly needed to b changed anyway) but that was fine to, I'm so far in the hole with this bike it would be worth more to us to keep it rather than sell it, I just want it to start first kick so my young bloke can get started, I think I need a miracle with this bike but it must b something simple