Having a hard time getting high octane fuel. What's the best way to drop compression a bit?

One option might be to double up on the base gasket... it will change the port timing a touch as well though. On that note, I would not expect a huge difference over all but even then I wouldn't really be able to say how much.

Edited September 28, 20223 yr by jonnyc21

I have a 270 beta that was hard to kick and very sharp off the bottom.  In addition to the standard 0.5 mm base gasket, I added a 1.0 mm base gasket.  The bike is noticeably softer off the bottom but I would not call the difference huge.  It is also easier to kick.  Swapping base gaskets is pretty easy to do and easily reversible.  

At some point in time, head spacers were sold for the same reason and should be even easier to install but probably unavailable.