You can replace the value on line 286 of the jetpack-carousel.js file, in the Carousel module folder:
http://plugins.trac.wordpress.org/browser/jetpack/trunk/modules/carousel/jetpack-carousel.js#L286
However, your changes will be overwritten next time you update the plugin. I'm afraid there is no other solution though, as it's not possible to change this value from outside the plugin. You will have to take notes of your changes and apply them once again once you have updated the plugin.