Also what happens when a piece of something or other comes loose from the motor and travels to the narrower part of the valve and obstructs the oil flow
Kinda like wooden timing wedges..??
I personally park the bike on the compression stroke, after shutting down for the day, (blocks the crank oil holes with pressure down from the rod bearings)
Bill, I don't want to sound argumentative, and I often read things wrong...?..but wouldn't any oil, and also any loose crap in the sludge trap, be able to flow back down into and through the T/S main bush ...? It may give some back pressure to the ball valve for a while until it's ll lost to the sump anyway..? Also the holes are in the sides of the rankpin, so it would be the same if it's @ TDC or BDC.
I have had some luck with warming the plastic extension tube, that comes with the carburetor cleaner spray can, and working it up through the sump two 90 degree bends to where the ball and spring live, and spraying the BAJESUS OUT OF IT
If you mean the sump oil pickup, I don't think there's any more spring-ball valves up there..is there??.. as far as I know the only ball up there is the one visible at the bottom of the scavenge pickup..with no spring, just back pressure in the return line- or have I missed something..?
The offending ball valve is in the feed side downstream from the pump....you'd only get at that-not- by going through the PRV....?
Personally I think better to park up with crank at BDC, so any oil flowing in can at least keep the crank gallery fed...?
..now, where's that bunker..?