Brand new SE compensating sprocket, A few weeks back. Regular 20w-50 oil. you get it up to temp on a ride, shut it off for 15 minutes, and on start up clatters to beat hell for 5-10 seconds. then everything is normal. I really don't think it's the lifters, these only have a couple thousand miles.
Jonnierock

 

What's your oil pressure on the gage when this is happening? Does the oil pressure go up after the noise stops? Installing a Baisley spring to increase oil pressure may be the ticket.

 

You didn't say how long the noise lasts. If it lasts less than 5 secs don't worry about it. Longer? Is there any carbon buildup in the cyl heads?