I have an 01 KX-500,with no manual,Ive put a quart in it and the sight glass is still not completely covered only half way and whats up with the ATF fluid which is better,thanks
2 stroke dosent have crankcase oil they have gearbox oil.
For the sight glass and oil level, just make sure its not empty or over the top. half way sound just good. i dont know for a mx as usually they ahve a oil check bolt instead but its how i used to do with quad and sight glass.
The proper amount of oil is probably stamped on the cover right by the oil fill port. If you can see it in the middle of the sight glass it is probably close though.