Well finally got a hundred miles on the rebuilt motor. Things have been going well until yesterday I heard a new noise when I got over 30 miles per hour. It's a rattle kind of sound. The wife said it sounds like the clatter when low on oil but a bit harsher. I've done some experimenting to narrow it down. It sound like coming from the engine and starts at around 2,000 rpm no matter what gear I'm in. When I first started hearing it, if I put in the clutch, it stops. So at stand still I rev the engine up 2,000 and no noise. Took it all the way to about 2,700 and no noise. No drips, no leaks, nothing I've check so far is low. If I get over that rpm and put the clutch in, it goes away. If I put in neutral and clutch out, it goes away. Where should I move to next.