as the title already says, what are the inner 4, and the big center hole on the motor mount for? Are they for airflow in order to cool the motor?

The outer four holes are for screwing down the motor.


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The centre hole can allow a shaft with collet to be used which can be if you reverse a shaft on some motors.

The inner holes can be used by smaller motors as the mount is pretty well a generic one that covers many different motor sizes. 
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The inner holes also allow you to mount the motor direct with no X mount or if you wanted to run the motor as a Inrunner. 
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