Re: what did you do to your motorized bicycle today?
So on the Diamond head the combustion chamber protrudes into the bore? that'll be nice since it can save time shaving the top of the jug down for sure. I'd use the copper gaskets from Juice to prevent gasket compression and get the squish clearance just above 1/4mm just to be sure the piston can't hit the head. the .016" thick gaskets he sells come out to about 0.4mm so by adding one of these at the base or at the head you'll end up with about a .65mm squish clearance which would put the compression ratio at a more reasonable level and prevent the piston from hitting after the engine warms up etc... As long as you keep the squish below 1mm you'll be in the acceptable range where it can still work to prevent detonation really well.
I know on my current running engine it has a 0.75mm squish clearance and the compression ratio came out to 12.7:1 so I run 93 octane premium and have no issues with detonation, of course, that's the static compression ratio and the actual is measured from the top of the exhaust port up making the effective compression ratio closer to around 8:1 or so.