Hey! I have been riding my ´75 CB500T for 14 years now. The eng.was seized when given it to me. It took a month to get the crank to move about 1 degree. Two weeks later it went all the way around and had compression in the left hole. Months later I decided to start it or scrap it. And now that it´s gone 67k ms., 26k with me on it, you say I might need unleaded valves? I sure hope not. It runs so good, 2 kicks cold start. I could use a starter though.