Clank

Just did a top end on another kz1000 . Fired up runs great. But first 30 seconds had a loud clank noise! Or more like a knock ,, not in time with anything ,thought what the hell. Shut it off, thought never heard that before Just a  clank knock noise. Put new pistons valves and springs all new gaskets . New timing Chan and all rubber components and idler. Never had this happen. But it sounded like is was coming apart. But now It runs great has ran up to temp. Letting cool down and firing it up later. Timing is spot on and vacuum gages are spot on.. has anyone had this happen. 

yes have had that happend after a total rebulid on my FJ1200 engine everything in engine was replaced  also the gearbox .only thing i did not replace was the crank and cases . Then started it up and clank clank clank clank clanketty-clank .Shut it off and was thinking ohh noo wt.... then did some inspections and could not find anything wrong. Then fired it up again  and no clanking.!!  i have now done about 30000 km and still runs great .
I think the clanking was because oil did not  distrubut fast enough . i also used assembly lube on all parts and the pistonskirts when rebuildt the engine so maybe that was a little to thick clogging up some oil passages .