Yeah. I had my engine out. All the fluid was out except the residual on everything. I put the engine back in teh bike and added some oil. Not very much, just a tiny bit. and it read full on the site glass. Here's the problem. The gasket for the clutch cover goes ABOVE the case. There is one spot where it is allowed to flow thru the gasket (at least the stock gasket). But it has edges to run over to get in there. I found it best to measure out 650ML and throw it in the bike. Then, I fire up the bike while it's on some jack stands supported on the stock brake guard and the frame right below the bottom engine mount. After it warms up, i run it thru the gears for a while. 5-10 minutes. Get her nice and warmed up. Then I check the site glass again. It's usually low when I fill from complete empty and requires a bit more. If it's disappearing, then I would point towards a leak. Either crank seal or something else.
On a 2 stroke it's hard to tell when you have a crank seal leak. It smokes... Well, this is where using ATF Type F really comes into play. IDK if you have ever smelled that sh*t burned. But it stinks like no other. I can tell be getting a whiff of the exhaust if it's leaking at the crank seals...