2005 CRF 230F ignition timing test - oil squirts when idling

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Hi,
I am trying to inspect the timing using a light.
The Factory manual says to do this at idle, but oil
squirts out the view hole when I attempt it.
Could / Should this area be dry? (left crankcase, flywheel, stator winding, etc.)
When I remove the cover, I can see through to the right side
of the crankcase.
How is it possible to check the timing when oil is squirting out of the hole?

Thanks and Happy New Year!