It's really not the CCA that's important but rather the duration of amperage delivered at 32 degrees F, which is the standard at which batteries are measured. You could have 1000 amps available to the starter motor but the windings will only accept whatever the motor is rated at anyway.
An example is a heavy truck. Most times you run 4 batteries in parallel and usually the batteries are at least 600CCA each so you have 2400CCA but the starter will only pull around 1000 amps @ 13.5 volts anyway. The 2400 gives you some reserve because, remember when you crank it, just like the bike, your alternator isn't providing a charge so it's a dead pull against the batteries.
Another example is your house wiring. Suppose you have 200 amp service. That means your main breakers will handle continuous amperage to 200 amps at before they thermally break. If you turn on a 100 watt light bulb, that light bulb is actually looking at 200 amps but the filament will only pass 100 watts or a little less than 1/10th of an amp. The starter motor is exactly the same scenario. That is governed by internal resistance. The only way the light bulb or your starter motor would consume all the available amperage is if there was a short to ground but that's what you have fuses (in your bike) and (in your breaker box) for.