Oil Level Viewing Glass Query

I think you're over-thinking the concern? Ensure the bike is on a Level surface !! Note the significant differences between "level", on the side-stand @ 7 degrees and on a "shimmed" side-stand @ 2 degrees off level ! The required level of adequate oil is referenced by the sight-glass. You could have a sump that held 10 liters of oil but the required level relative to the Base of the engine block would be the same. Same principle as the fuel-bowl level. The bowl could be 6" deep but the required level of fuel relative to the base of the carb-body doesn't change.

Well that's an eye opener!!! Will check straight away. Thank you .

I can't see through mine.
Does anyone know how to get them out to clean them pls?