Shineray 200XYI: impossible to remove valve cover?

[thedakotakid]

Judging by how impossible it seems to remove the valve cover, I am guessing no one has adjusted the valves since new. The problem is the clearance between the frame and the head. I got so desperate I took out most of the engine bolts to try to get it to drop a bit for more clearance. I can rotate the valve cover, but I can't get it off. Yes I tried to crank over the engine slowly and see if I could clear it. Other than pulling the engine, any suggestions?