The valves are adjusted at room temperature (68 to 72 degrees F) with the piston near TDC of the compression stroke - the engine has to be rotated counterclockwise from the LH end - if the piston does not stop at TDC, it cannot be turned clockwise to get to TDC - doing so will activate the auto decompressor and affect the setting of the RH exhaust valve.
The engine does not have to be exactly at TDC as long as the rocker arm pads are on the base circle portion of the camshaft. You can stop a few degrees before TDC or a few degrees after TDC as long as the crankshaft does not turn clockwise from TDC due to the magnetic attraction of the rotor to the stator. So if it wants to rotate clockwise when stopping at TDC, go past TDC to the point the magnets stop turning the crankshaft CCW.
At this point, adjust all 4 valves to the prescribed clearance. Note: it is better to be loose a thousandths or two instead of tight a thousandths or two.