200s warm up noise

[1984 honda 200s]

As you all know i rebuilt my 84 200s at the beginning of this month with a .20 over sized Weisco piston and rings and redone the valves (.002)
Ive noticed on warm up ( -15C) the engine seems to KNOCK after about 5 mins of warm up time then go away within 20mins of warmup..
Is this normal for the new engine to knock? it is terribly cold out.. i was kind of worried about it.. But when its warm the knocking goes away and sounds like a new machine.
No shortage of power and TONS of compression

[dougspcs]

Probably piston slap..

Who ever bored the cylinder to fit your oversize piston probably went a few thousands over causing a bit too much piston movement in the cylinder.

As the piston warms up and expands it tightens up..

[muthey]

if it was summer time I would consider that maybe the oil is not staying up on the top of the rockers, but much too cold for it to run off as easily, did you remember to put the little black nub back into the head when you reassembled as that helps control the flow of oil to the rocker arms. is it more of a tick or an actual knock? did you make sure the gasket material was fully cleaned out of all the oil pathways?

[1984 honda 200s]

Well i thought of it after that it just might be from it being so cold, the oil thickens up.... The cylinder head and valves was done by my cousin, it was cleaned up and yes the black rubber nub was put back into place..
Its deffinatly a knock, when i first start it, it runs normal no noise, then about 5 mins later it starts to make a noticable knock then goes away when the engine is totally warmed up.
Today was very mild out about 4c when i let it warm up there wasnt any knocking...its always when its cold -5 and colder.
Tomorrow is supposed to be cooling down, so i will try to take a quick video of warm up and post it.