I am rebuilding an H25 from 1967. There is no timing mark on the crank and there are no beveled teeth on it either. I tried lining the timing mark on the cam to the tooth on the crank that is lined up with the key but the engine will not start. It will pop now and then but won't start. I have checked everything else many times and still, the only thing that I can think of is the timing. It has a new carb on it also and I have spark. Everything checks out. As far as I know, I was the first person to open the engine up since it was new.