Perhaps someone can help.
1.As I understand it, the camshaft gets its oil supply when the pressure release valve opens.
2.If the engine is cold, oil is thick and pressure release valve opens ? everything gets plenty of oil
3.Engine gets hot, viscosity falls and the oil pressure drops down to say 30 psi or less.
4.Pressure release valve now stays closed for the rest of the run as it only opens at above 50 psi.
5.Park the bike things cool down, viscosity goes up valve opens, start all over again - fine.
So, to keep your camshaft well lubricated don't drive for hours on end without letting things cool down ????
My GF has a tired main bearing and I have fitted an external pressure gauge to see what is going on. I pick up the pressure before the release valve. When cold, pressure shots up and stays around 50 psi where the valve opens. Once the engine gets hot this falls away and I am running around on about 15/20 psi oil temp 70C (don't worry I am about to change out the main). Surely, anyone who has a less than perfect timing side main is possibly going to have problems on a longer run with lubrication of the camshaft and followers unless the oil supply from the rocker box is sufficient to lubricate the cam when the engine is hot ????
Sorry If this all seems a bit daft but I am really struggling to believe that the oil pressure release valve on most bikes opens again once the engine is up to running temperature.
PS I fitted a new SRM release valve and found this opened around 70 psi so this baby will shut off oil even earlier
Nigel