dool you re more than welcome in offtopic chat we like noobs
man you cant quote a rebuild till the engine is apart.
Then it comes down to how much of a tight ass you are, and how "right" your going to have it built.
but, go put some nice thick oil in it, and see if it shuts it up.
if it was bottom end, it would do it all the time, especially on start up.
so i would say its top end, if its the engine at all, could just be a vibration lol.
THICK OIL