NO - as Andy has said the scavenging side has greater capacity then the feed side therefore it pumps what oil is in the sump and a certain quantity of air which is also present in the sump, this results in a intermittent (spluttering) return into the oil tank.
Also means the sump should be almost empty when the engine is stopped other than oil that is clinging to surfaces inside the engine, drains down from the rockers and I suppose anything that slurps (nice word that) over the camshaft through when the bike is hauled onto the stand.
The amount that drains down from the rockers is of interest, I assume there is a limit to the amount that will pass past the cam followers in any given time, if the rockers are over fed then there could be a build up in the pushrod tunnel giving rise to symptoms similar to those described but it's not one I've heard of before.
All the best - Bill
Sorry Bill I have to disagree, If the sump is almost empty except clinging oil you'd have a serious problem, more than likely a seized engine, it is not only the big ends etc that require oil, the camshaft (certainy long stroke engines as they do not have a trough) & more importantly cylinder bores rely on oil throw/pressurised mist from the crank, without it they'd seize.
Also acts as a coolant.
These engines are designed to be pressurised to a point (hence timed breathers) to enable oil to lube aforesaid & oil control rings are there to prevent that oil progressing into the head itself.
Spluttering from the return is proportional to engine/oil pump rpm. At tickover it splutters, at higher revs it'a constant flow.
Short of us all going for a ride, draining our sumps into our wives finest measuring jugs & establishing an average I would say anything from 1/4 to 1/2 a pint acceptable.
But we digress, getting back to the point, I think Groily has the most plausible explanation, rings, or as my earlier post, rocker feed bolts with dirty great holes & its flooding through the valves & into the head. I'd put money, if I wasn't so tight on Groily's theory.
Anyway enough of this I'm off to wet sump with a few a few pints of Fullers finest.
For those not familiar, think heavy monograde, lubricates well, relieves stress from vital components, but can cause difficulty starting of a morning