It's the oil level all right, the motor is in bits so I can see inside.
It's low down on the clutch cover. Just above one of the side case screws.
Not sure about the 250 though.
I've tried to find a piccie but no joy.
Just checked the ALPHA Sports website, looks like the 250 plug is behind the clutch bulge, probably below the kick start shaft.
Might have to wait for a 250 owner to log on.....
Brent