RESolute

Why would I want help from someone who, the first time they introduce themself to me, gives me the finger?

I'm rebuilding a 1978 yz125 I've have since I was 19 years old..I turned 55 this past Sunday. I bought it one year old in 1979. Having trouble figuring out what to do with the worn out top end though. I found a used barrel that mikes at 57.5 mm, and it will need to be bored. The problem is that the jug I received in the mail doesn't look like the one on the bike, and I think the one on the bike is a dt125 jug, and the different one I received is the right one! The one on the bike has 4 holes (to accomodate a socket) down through every fin, if that helps. I will post pix of each soon. The biggest problem is not knowing which next oversized piston kit to get, and how much bigger than the piston does the new bore need to be. Can someone please provide guidance? Thank you.