CSC says 0.07 mm (snug 0.003, sloppy 0.002 inches)
They make more work of the task than necessary, no need to remove the tank.
http://californiascooterco.com/blog/?p=19832
I think when mine arrives, I'll do a sloppy 0.003 inches, maybe even more on the exhaust. I suspect it won't be sloppy for long.