Each motorcycle engine is different, and therefore pressure readings will be different. Pressure will also vary with temperature and engine RPM. A specific manual is needed to know exact pressure requirements, but there are some basic guidelines to pressure.
There are two basic oiling systems in a motorcycle -- wet and dry sump systems. Wet sump systems are similar to those in a car. The oil resides in an oil pan and is pumped to engine parts by a mechanically driven oil pump. The dry sump has a remote reservoir and pumps the oil from the reservoir to the engine and back again through oil lines. Dry sump systems are usually lower pressure systems. Both systems use a filter to clean the oil.
Many things affect pressure, including amount and type of oil, temperature and engine speed. Oil levels must be checked frequently, and the right oil specification must be used to achieve ideal oil pressure. Check with your dealer for the specifications for your bike. Outside temperature and oil temperature affect pressure as well. On hotter days, oil pressure will be lower. Although most bikes tolerate lower pressure at idle, once certain engine RPMs are reached, pressure must increase as well.
The Bottom Line
Most bikes need some pressure at idle and between 20 and 90 psi at various engine speeds. If the oil light flickers at idle or the gauge drops into the red, investigate the lubrication system from the bottom up, including filters and oil lines.