Just an update before this thread dies off forever.
We cut a new slot with a dremel and it came right out. Turns out the valve clearances are fine. Thank you guys. I wanna try that heat idea some time, I like fire
'83 Honda XL600R 618cc 11:1 Wiseco, XR's Only Exhaust, big tube header, 6 Sigma stage 3 carb mods