[ChalkWhite]

Could it be a cam chain tensioner not being pumped up all the way? I’m not familiar with that on this motor but, I’ve experienced it on many other brands. The slapping of the loose timing chain is loud and rythmic before the tensioner gets pumped full of oil...

 

[ChalkWhite]

The motor that I had with the most cam chain noise from a non-pumped up tensioner was on a BMW R1100 motorcycle and it was only noisy when it was left for a few weeks without being started. Over time the oil would bleed out of the tensioner and the cam chain would raise a racket until it was warmed up. If I ran it more regularly it wouldn’t have the behavior. I changed out the tensioner eventually and most of the startup noise after letting it sit for a few weeks went away.
If the noise goes away and doesn’t recur when you drive it more regularly, it could be this.