I'm going to give you the best advice so far, save your money and take it to somebody that knows what they are doing. I give you an A for enthusiam and an F for knowledge, those make a bad combination, I know this from personal experience. At a little older than you my bike was a 125 Hodaka Combat Wombat, every dime I made went into that bike, mostly because I thought I knew what I was doing and probably didn't. I could also say thats why I know what I know but back in those days a piston was only like $12 and granted that was alot of money back then. The kx 60 is a grenade waiting to happen, I have seen countless 60's blown up usually its the crank from doing exactly what you described riding in a low gear and revving to the moon. So either fix it right or plan on going into it again and again and so on.
Are you just learning to ride? 13 for a 60 seems a bit old
