Just did a squish test, but...
 

The damn solder is not smashed! I am using the right solder (.093 rosin).
Just looking at the height of the piston at TDC and comparing it to the head it doesn't even look like it would come in contact with the solder. What the hell?

Use .125 acid core solder, you can get this from a local NAPA auto parts store, part number 777-1857

Ron

0.93" is equal to 2.3mm.

That's a lot of squish -- to mod.

Some may argue with me here, but when I did mine I used modeling clay. Take off the head, put a ball of modeling clay on top of the piston at the edge, bolt the head back on and torque to spec. Next you will gently move the starter to get the piston to and past top dead center. I wouldn't crank on it, because you could potentially send modeling clay into your ports, or bottom end or whatever nightmare you can think of. Not likely, but I don't recommend it.
Take the head off, then measure the clay.

I would not be surprised if you had a squish of .95, mine was .85. You will be floored at the diffference. My throttle response rocks. Bike runs better, easier to jet, more power, no detonation.