Does it need to be done with engine hot or cold ?

its not the scoob, its my bike.

cold, the compression is 50 PSI lower on all 4 bores than stated in manual.

cant start it as yet, but have been told cold readings dont count, its when the engine is warm, but im a bit on that one, surely i shouldnt have bores 50 PSI down on all 4 of them when cold, surely ????

any info appreciated

cheers