Ok here is the deal.
When it is cold the thing sounds like it is coming apart (tapping and knocking). I have tried all the normal stuff, I run fresh lightweight oil (today's high temp was 8F), checked the valve clearance and timing. As soon as the temp gauge moves it starts to quiet down till at full temp it sounds normal.

 

If it's a clicking sound, then it's normal. Mine does that too. When you start it up cold, the clicking lasts for about 2minutes. In the summer, it should only last for about 30 seconds. It has to do with the oil draining overnight or whenever it's not in use.