Question for racking with CO2

I purchased a few things to try out racking with CO2 (i.e., as opposed to using an autosiphon, and/or as opposed to using mouth siphoning or blowing). It wasn’t as smooth and elegant a method as autosiphoning, in my opinion, so I have a few questions:

  • Is it common for the carboy caps to [u]not[/u] be air-tight? Should I hear any hissing of air as it leaks?[/*]
  • How quickly do I need to turn off the CO2? There's a point at which the racking cane is above the liquid level, and then the system is still actively pushing CO2---through the racking tube, all the way to the bottom of my keg, and bubbling / burping up from the bottom.[/*]
  • Related to the above, I assume the bubbling / burping of the CO2 won't harm the beer? Doesn't seem like it would, but then, the burping/bubbling does create a splashing effect at the air/liquid interface in the keg.[/*]
  • I didn't have tubing that matched the diameter of the racking cane, so I ended up using tubing that was quite a bit bigger. The wort then, of course, only filled about half of the cross-sectional area of the tubing. Is this an oxidation issue? Or a non-issue?[/*]

When I have done this I use the orange caps with 2 openings and they sealed fine. I would purge the whole system with co2 first so oxidation is not an issue. The co2 bubbling isn’t a problem either; if anything it starts your beer on its way to carbonation.